Altered morphogenesis of the immature hamster uterus following neonatal exposure to diethylstilbestrol

Abstract. In previous studies, we found that a single neonatal exposure to diethylstilbestrol (DES) resulted in severe hyperplasia and a high incidence of endometrial adenocarcinoma in the uterus of adult hamsters. These observations prompted us to investigate the consequences of DES exposure on earlier stages of uterine morphogenesis. After neonates were treated within 6 h of birth (day 1) with 100 μg of DES or oil vehicle, uterine tissue morphometry plus cell labelling indices following in vivo pulse labeling with [³H]thymidine were determined on days 3–21 of life. The sequential findings were: (1) a precocious (day 3) burst of cellular proliferation throughout the uterus, (2) an early period (days 3–9) of hypertrophy and increased cell density in the luminal epithelium, (3) an extreme acceleration of uterine growth resulting in a persistent increase in total uterine mass (threefold enhancement on days 5–21), (4) precocious development of endometrial glands (day 9) that were sites of intense but transient proliferative activity, (5) a middle period (days 9–15) when the percentage of stromal cells engaged in proliferative activity was reduced, (6) a second wave (days 15–21) of enhanced proliferative activity in the luminal epithelium, and (7) later development (day 21) of reduced cell density in the uterine stroma, apparently due to increased intercellular collagen accumulation. These results support our working hypothesis that the acute uterotropic response to neonatal DES treatment initiates a change in the developing hamster uterus, and later estrogenic stimulation promotes neoplastic progression in the DES-altered adult organ, perhaps due to disruption of stromal-epithelial interactions.     

Spatial and temporal patterns of urea content in a eutrophic stream continuum on the Northern Great Plains

Biogeochemistry - Urea can degrade water quality and stimulate toxic phytoplankton in P-rich lakes, yet little is known of its sources, abundance, or transportation in lotic systems, particularly...     

Wild-type huntingtin reduces the cellular toxicity of mutant huntingtin in vivo

We have developed yeast artificial chromosome (YAC) transgenic mice expressing normal (YAC18) and mutant (YAC46 or YAC72) human huntingtin (htt), in a developmental- and tissue-specific manner, that is identical to endogenous htt. YAC72 mice develop selective degeneration of medium spiny projection neurons in the lateral striatum, similar to what is observed in Huntington disease. Mutant human htt expressed by YAC transgenes can compensate for the absence of endogenous htt and can rescue the embryonic lethality that characterizes mice homozygous for targeted disruption of the endogenous Hdh gene (-/-). YAC72 mice lacking endogenous htt (YAC72 -/-) manifest a novel phenotype characterized by infertility, testicular atrophy, aspermia, and massive apoptotic cell death in the testes. The testicular cell death in YAC72 -/- mice can be markedly reduced by increasing endogenous htt levels. YAC72 mice with equivalent levels of both wild-type and mutant htt (YAC72 +/+) breed normally and have no evidence of increased testicular cell death. Similar findings are seen in YAC46 -/- mice compared with YAC46 +/+ mice, in which wild-type htt can completely counteract the proapoptotic effects of mutant htt. YAC18 -/- mice display no evidence of increased cellular apoptosis, even in the complete absence of endogenous htt, demonstrating that the massive cellular apoptosis observed in YAC46 -/- mice and YAC72 -/- mice is polyglutamine-mediated toxicity from the mutant transgene. These data provide the first direct in vivo evidence of a role for wild-type htt in decreasing the cellular toxicity of mutant htt.     

Modulation of microfilament protein composition by transfected cytoskeletal actin genes.

HuT-14T is a highly tumorigenic fibroblast cell line which exhibits a reduced steady-state level of beta-actin due to coding mutations in one of two beta-actin alleles. The normal rate of total actin synthesis could be restored in some clones of cells following transfection of the functional beta-actin gene but not following transfection of the functional gamma-actin gene. In gamma-actin gene-transfected substrains that have increased rates of gamma-actin synthesis, beta-actin synthesis is further reduced in a manner consistent with an autoregulatory mechanism, resulting in abnormal ratios of actin isoforms. Thus, both beta- and gamma-actin proteins can apparently regulate the synthesis of their coexpressed isoforms. In addition, decreased synthesis of normal beta-actin seems to correlate with a concomitant down-regulation of tropomyosin isoforms.     

Expression of the polyomavirus minor capsid proteins VP2 and VP3 in Escherichia coli: in vitro interactions with recombinant VP1 capsomeres.

The polyomavirus VP2 and VP3 capsid proteins were expressed in Escherichia coli. The majority of the expressed proteins were in an insoluble fraction, and they were extracted and initially purified in 8 M urea before renaturation. Soluble VP2 and VP3 were mixed with purified recombinant VP1 capsomeres, and their interactions were assayed by immunoprecipitation and ion-exchange chromatography. Coimmunoprecipitation could be demonstrated with antibodies to either VP1 or VP2/VP3. Mixing recombinant VP1 with VP2 and VP3 modified the recognition of VP1 by domain-specific antipeptide antibodies and altered the chromatographic behavior of the individual proteins. Similar results were observed when a truncated VP1 protein, delta NCOVP1, with 62 amino acids deleted from the carboxy terminus was mixed with VP2/VP3. After the mixing, equilibrium dissociation constants for their binding to either VP1 or delta NCOVP1 were determined to be 0.37 +/- 0.23 microM for VP2 and 0.18 +/- 0.21 microM for VP3. These studies demonstrate that the recombinant VP2 and VP3 proteins interact with VP1 to affect the biochemical properties of VP1 capsomeres and to change the epitope accessibility of VP1 pentamers. These changes may reflect conformational alterations in VP1 capsomeres which are necessary for viral genome encapsidation.     

One-step refolding and purification of disulfide-containing proteins with a C-terminal MESNA thioester

Background  

Expression systems based on self-cleavable intein domains allow the generation of recombinant proteins with a C-terminal thioester. This uniquely reactive C-terminus can be used in native chemical ligation reactions to introduce synthetic groups or to immobilize proteins on surfaces and nanoparticles. Unfortunately, common refolding procedures for recombinant proteins that contain disulfide bonds do not preserve the thioester functionality and therefore novel refolding procedures need to be developed.     

Synthesis and SAR of 2,3-diarylpyrrole inhibitors of parasite cGMP-dependent protein kinase as novel anticoccidial agents

Several analogs of 2,3-diaryl pyrroles were synthesized and evaluated as inhibitors of Eimeria tenella cGMP-dependent protein kinase and in in vivo anticoccidial assays. A 4-fluorophenyl group enhances both in vitro and in vivo activities. The most potent analogs are the 5-(N-methyl, N-ethyl, and N-methylazetidine methyl) piperidyl derivatives 12, 23, and 34. These compounds have a broad spectrum of activity. Based on the in vivo efficacy and cost of synthesis, the N-ethyl analog 23 was chosen as a novel anticoccidial agent for a field trial.