The measurement of steroid glucuronides in urine from mice to monitor gonadal function. I. Pregnanediol-3 alpha-glucuronide as an index of progestogen output

An attempt has been made to assess the output of progesterone in mice by measuring the concentration of pregnanediol-3 alpha-glucuronide (PdGl in serial samples of unextracted urine. Longitudinal studies with 95 animals have shown that sufficient urine (greater than 40 microliter) can be obtained from individual animals (80% success rate) without stress every day or at intervals of 2 h. The sc administration of 50 microgram progesterone in lauric acid ethyl ester resulted in a 9-fold increase in the concentration of urinary PdGl (within 4 h) and a significantly elevated output for the next 26 h. During the induction of superovulation with PMS and hCG, the values of PdGl increased significantly (P less than 0.0005; by Student's t test) from 2.08 +/- 0.97 to 3.99 +/- 2.55 ng/ml (mean +/- SD) at the time of corpus luteum formation. There was a good correlation (r = 0.84; n = 154) between the values expressed as nanograms per ml urine and nanograms per mg creatinine. The results demonstrate that the concentration of PdGl in serial samples of urine may be used as an index of gonadal function in female mice.     

A constitutively active epidermal growth factor receptor cooperates with disruption of G1 cell-cycle arrest pathways to induce glioma-like lesions in mice

The epidermal growth factor receptor (EGFR) gene is amplified or mutated in 30%-50% of human gliobastoma multiforme (GBM). These mutations are associated usually with deletions of the INK4a-ARF locus, which encodes two gene products (p16(INK4a) and p19(ARF)) involved in cell-cycle arrest and apoptosis. We have investigated the role of EGFR mutation in gliomagenesis, using avian retroviral vectors to transfer a mutant EGFR gene to glial precursors and astrocytes in transgenic mice expressing tv-a, a gene encoding the retrovirus receptor. TVA, under control of brain cell type-specific promoters. We demonstrate that expression of a constitutively active, mutant form of EGFR in cells in the glial lineage can induce lesions with many similarities to human gliomas. These lesions occur more frequently with gene transfer to mice expressing tv-a from the progenitor-specific nestin promoter than to mice expressing tv-a from the astrocyte-specific glial fibrillary acidic protein (GFAP) promoter, suggesting that tumors arise more efficiently from immature cells in the glial lineage. Furthermore, EGFR-induced gliomagenesis appears to require additional mutations in genes encoding proteins involved in cell-cycle arrest pathways. We have produced these combinations by simultaneously infecting tv-a transgenic mice with vectors carrying cdk4 and EGFR or by infecting tv-a transgenic mice bearing a disrupted INK4a-ARF locus with the EGFR-carrying vector alone. Moreover, EGFR-induced gliomagenesis does not occur in conjunction with p53 deficiency, unless the mice are also infected with a vector carrying cdk4. The gliomagenic combinations of genetic lesions required in mice are similar to those found in human gliomas.