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In this report we describe an effective method for delivery of a novel snake venom disintegrin, contortrostatin (CN), in an orthotopic, xenograft model of human mammary cancer in immunodeficient mice. Contortrostatin (Mr 13,500) is a homodimeric disintegrin isolated from venom of the southern copperhead snake. Contortrostatin possesses two RGD sites, one in each chain, which modulate its interaction with integrins on tumor cells and angiogenic vascular endothelial cells. Although our laboratory has previously described the antitumor activity of CN in a mouse model of human mammary cancer, the method of delivery, daily intratumor injection, was not translatable to clinical application. We now describe a clinically relevant method of administering CN, liposomal delivery (LCN). A unique liposomal system has been designed for intravenous (IV) administration of a biologically active protein with full retention of biological activity. Pharmacokinetics, biodistribution, platelet reactivity, and immunogenicity of LCN were examined and compared with similar characteristics of native, unencapsulated CN. There are several advantages to liposomal delivery of CN: (i) LCN has a significantly prolonged circulatory half-life compared to native CN; (ii) LCN is passively accumulated in the tumor; (iii) LCN has no platelet reactivity; and (iv) LCN is not recognized by the immune system. We have previously demonstrated that antiangiogenic activity is an important component of CN's mechanism of antitumor action. In the present communication we demonstrate that IV delivery of LCN leads to potent antitumor and antiangiogenic activity in the orthotopic, xenograft human mammary cancer model. [ABSTRACT FROM AUTHOR]

Newborn Swiss‐Webster mice were exposed to intermittent 0.3 ppm ozone (O 3 ) for 6 wk, and the lungs of 137 exposed and 138 control animals (275 of the 301 in the colony) were suitable for computer‐assisted image‐analysis quantitation. Data were obtained on numbers and areas of lactate dehydrogenase stained type II cells, and also area, perimeters, and linear intercepts of the alveolar wall. As noted in an earlier study of adult mice, ozone exposure increased all cell and wall measurements. In contrast to the adult animal findings, there was a greater increase in mean type II cell area (p = 0.07) than in numbers of type II cells, with the latter increase falling short of statistical significance. The increase in cell area at the expense of cell number may largely be due to cell pairing or multicell clustering, events that would mask type II cell hyperplasia. Ozone effects on the type II cell population implicate damage to the type I alveolar lining cells. Moreover, the increases in alveolar wall measurements that were found in both the adult and developing mouse lung imply an alteration of the lung scaffolding, and this raises the question of impaired regeneration of the epithelial lining. [ABSTRACT FROM PUBLISHER]

Examines the hyperplasia of type two pneumocytes on an ambient level of nitrogen dioxide exposure. Enlargement of the type two cell; Adjustment of alveolar wall measurements for lung volume normalization; Significance of cell population on the level of nitrogen dioxide exposure.

Serum and tissue homogenates of lung and kidney from 264 mice, half of which had been exposed to continuous or intermittent nitrogen dioxide (NO3 at levels of 0.5 ppm, 0.6 ppm, and 0.8 ppm in three independent experiments, were assayed for intravenously introduced horseradish peroxidase (HRP), a molecular probe for protein leakage. Disc gel elec-trophoresis and enzyme kinetic assays were used independently to quantitate HRP content after 3 and 6 weeks of NO2 exposure, and at 5.5 hr after HRP injection. Of 6 test periods, 5 showed a greater lung HRP content for the NO2, exposed animals by gel scan analysis, and 3 of the 5 increases were statistically significant (p >.05, p >.025, and p >.0025). Similar trends were noted with the HRP kinetic assay. Serum and kidney comparisons showed no consistent differences; 1 of 6 test periods for each was statistically significant. The findings implicate an NO2, induced overload of the bidirectional protein transport system of the lung. [ABSTRACT FROM PUBLISHER]

Lung lavage and disc-gel electrophoresis of the lavage fluid were carried out in a study of 18 guinea pigs, half of which were exposed continuously over a one-week period to 0.4 ppm nitrogen dioxide. Of the nine animal pairs, eight were characterized by higher protein levels for the exposed animals (P<.001). The values for eight of nine control animals were .1097 (arbitrary units) or less, whereas those for eight of nine exposed animals had levels .1164 or higher, with a maximum of .1698. The methodologies represent a relatively simple means of detecting a physiologically important alteration and have the potential of greater sensitivity to and specificity of protein content through new advances in electrophoretic techniques. [ABSTRACT FROM AUTHOR]

A preliminary testing of eight guinea pigs for D-2,3-diphosphoglycerate (2,3- DPG) content of red blood cells, half of which had been exposed to continuous 0.36 ppm nitrogen dioxide for one week, showed a significant increase (P <.05)for the exposed animals. [ABSTRACT FROM AUTHOR]

Investigates the protein leakage in the lungs of mice due to exposure to nitrogen dioxide. Description of flourescamine; Amount of protein found in the lung lavage fluid; Comparison between methodologies in detecting fluid leakage.

Despite significant research in this area, metastatic breast cancer remains a disease with a poor prognosis. Until an effective therapy is developed, it is imperative that new treatment modalities be investigated. In this report, we describe an effective method for delivery of a novel snake venom disintegrin, contortrostatin (CN), in an orthotopic, xenograft model of human mammary cancer in immunodeficient mice. CN (Mr 13,500) is a homodimeric disintegrin isolated from venom of the Southern Copperhead snake. The homodimer possesses two Arg-Gly-Asp sites, which modulate its interaction with integrins on tumor cells and angiogenic vascular endothelial cells. Although our laboratory has previously described the antitumor activity of CN in a mouse model of human mammary cancer, the method of delivery, daily intratumor injection, was not translatable to clinical application. We now describe a clinically relevant method of administering CN, liposomal delivery (LCN). A unique liposomal system has been designed for i.v. administration of a biologically active protein with full retention of biological activity. Pharmacokinetics, biodistribution, platelet reactivity, and immunogenicity of LCN were determined and compared with similar characteristics of native, unencapsulated CN. There are several advantages to liposomal delivery of CN: (1) LCN has a significantly prolonged circulatory half-life compared with native CN; (2) LCN is passively accumulated in the tumor; (3) LCN has no platelet reactivity; and (4) LCN is not recognized by the immune system. Finally, antiangiogenic activity is an important component of CN's mechanism of antitumor action. We have demonstrated that i.v. delivery of LCN leads to potent antiangiogenic activity in the orthotopic, xenograft human mammary tumor model.