Lactation-induced WAP-SV40 Tag Transgene Expression in C57BL/6J Mice Leads to Mammary Carcinoma

Two transgenic lineages were generated by directing the expression of SV40 T antigen to the mammary gland of inbred C57BL/6J mice using the whey acidic protein (WAP) promoter. In one lineage, WAPTag 1, multiparous female mice developed mammary adenocarcinoma with an average latency period of 13 months. The histopathological phenotype was heterogeneous, tumours occurred in a stochastic fashion, normal tissue was located next to neoplastic tissue, the mammary tumours usually developed and were remarkably similar to that observed in human cases. In addition, male and virgin females developed a poorly differentiated SV40 T antigen-positive soft tissue sarcoma, also at 13 months of age. In the other lineage, WAPTag 3, some parous females developed mammary tumours, but most mice succumbed to osteosarcomas arising from the os petrosum at 5.5 to 6 months of age and on necropsy, renal adenocarcinomas were also found. Appearance of these unexpected tumour types demonstrates the non-specific e...     

Enantiomerically pure 3-hydroxypropyl diisopropylidene mannose derivatives

Enantiomerically pure 3-hydroxypropyl diisopropylidene mannose derivatives were prepared and fully characterized. The procedure is generally applicable to monosaccharides and thus facilitates access to differently substituted glycosidic precursors.     

Recombinant human VEGF treatment transiently increases lung edema but enhances lung structure after neonatal hyperoxia

Recent studies suggest that VEGF may worsen pulmonary edema during acute lung injury (ALI), but, paradoxically, impaired VEGF signaling contributes to decreased lung growth during recovery from ALI due to neonatal hyperoxia. To examine the diverse roles of VEGF in the pathogenesis of and recovery from hyperoxia-induced ALI, we hypothesized that exogenous recombinant human VEGF (rhVEGF) treatment during early neonatal hyperoxic lung injury may increase pulmonary edema but would improve late lung structure during recovery. Sprague-Dawley rat pups were placed in a hyperoxia chamber (inspired O(2) fraction 0.9) for postnatal days 2-14. Pups were randomized to daily intramuscular injections of rhVEGF(165) (20 microg/kg) or saline (controls). On postnatal day 14, rats were placed in room air for a 7-day recovery period. At postnatal days 3, 14, and 21, rats were killed for studies, which included body weight and wet-to-dry lung weight ratio, morphometric analysis [including radial alveolar counts (RAC), mean linear intercepts (MLI), and vessel density], and lung endothelial NO synthase (eNOS) protein content by Western blot analysis. Compared with room air controls, hyperoxia increased pulmonary edema by histology and wet-to-dry lung weight ratios at postnatal day 3, which resolved by day 14. Although treatment with rhVEGF did not increase edema in control rats, rhVEGF increased wet-to-dry weight ratios in hyperoxia-exposed rats at postnatal days 3 and 14 (P < 0.01). Compared with room air controls, hyperoxia decreased RAC and increased MLI at postnatal days 14 and 21. Treatment with VEGF resulted in increased RAC by 181% and decreased MLI by 55% on postnatal day 14 in the hyperoxia group (P < 0.01). On postnatal day 21, RAC was increased by 176% and MLI was decreased by 58% in the hyperoxia group treated with VEGF. rhVEGF treatment during hyperoxia increased eNOS protein on postnatal day 3 by threefold (P < 0.05). We conclude that rhVEGF treatment during hyperoxia-induced ALI transiently increases pulmonary edema but improves lung structure during late recovery. We speculate that VEGF has diverse roles in hyperoxia-induced neonatal lung injury, contributing to lung edema during the acute stage of ALI but promoting repair of the lung during recovery.     

Impaired VEGF and nitric oxide signaling after nitrofen exposure in rat fetal lung explants

We hypothesized that abnormal fetal lung growth in experimental congenital diaphragmatic hernia after maternal nitrofen exposure alters lung structure due to impaired VEGF signaling, which can be reversed with VEGF or nitric oxide (NO) treatment. Timed-pregnant Sprague-Dawley rats were treated with nitrofen on embryonic day 9 (E9), and fetal lungs were harvested for explant culture on E15. Explants were maintained in 3% O2 for 3 days and were treated with NO gas or recombinant human VEGF protein for 3 days. To determine the effects of VEGF inhibition on lung structure, normal fetal lung explants were treated with SU-5416, a VEGF receptor inhibitor, with or without exogenous NO or VEGF. We found that nitrofen treatment impaired lung structure, as evidenced by decreased branching at day 0, but lung structure was not different from controls after 3 days in culture. Nitrofen reduced lung VEGF but not endothelial NO synthase protein level. Treatment with NO enhanced lung growth in control and nitrofen-exposed lungs; however, the response to NO in the nitrofen-treated lungs was reduced when compared with controls. VEGF treatment did not cause a further increase in lung complexity after nitrofen exposure. SU-5416 treatment altered lung structure, which improved with NO but not VEGF treatment. Both nitrofen and SU-5416 treatment increased apoptosis in the mesenchyme of fetal lung explants. We conclude that nitrofen exposure increased apoptosis, decreased lung growth and reduced VEGF expression, and that exogenous NO but not VEGF treatment enhances lung growth. Disruption of lung architecture after VEGF receptor blockade was similar to nitrofen-induced changes but was more responsive to NO.     

Recombinant human VEGF treatment enhances alveolarization after hyperoxic lung injury in neonatal rats

VEGF signaling inhibition decreases alveolar and vessel growth in the developing lung, suggesting that impaired VEGF signaling may contribute to decreased lung growth in bronchopulmonary dysplasia (BPD). Whether VEGF treatment improves lung structure in experimental models of BPD is unknown. The objective was to determine whether VEGF treatment enhances alveolarization in infant rats after hyperoxia. Two-day-old Sprague-Dawley rats were placed into hyperoxia or room air (RA) for 12 days. At 14 days, rats received daily treatment with rhVEGF-165 or saline. On day 22, rats were killed. Tissue was collected. Morphometrics was assessed by radial alveolar counts (RAC), mean linear intercepts (MLI), and skeletonization. Compared with RA controls, hyperoxia decreased RAC (6.1 +/- 0.4 vs. 11.3 +/- 0.4, P < 0.0001), increased MLI (59.2 +/- 1.8 vs. 44.0 +/- 0.8, P < 0.0001), decreased nodal point density (447 +/- 14 vs. 503 +/- 12, P < 0.0004), and decreased vessel density (11.7 +/- 0.3 vs. 18.9 +/- 0.3, P < 0.001), which persisted despite RA recovery. Compared with hyperoxic controls, rhVEGF treatment after hyperoxia increased RAC (11.8 +/- 0.5, P < 0.0001), decreased MLI (42.2 +/- 1.2, P < 0.0001), increased nodal point density (502 +/- 7, P < 0.0005), and increased vessel density (23.2 +/- 0.4, P < 0.001). Exposure of neonatal rats to hyperoxia impairs alveolarization and vessel density, which persists despite RA recovery. rhVEGF treatment during recovery enhanced vessel growth and alveolarization. We speculate that lung structure abnormalities after hyperoxia may be partly due to impaired VEGF signaling.