Live birth of a bear cub following nonsurgical embryo collection.

In the near future, 6 of 8 bear species will face extinction mainly because of loss of their natural habitat. This loss of habitat will ultimately require some of these bears to be maintained in zoos and wildlife preserves in the hope of conserving genetic diversity. If the giant panda is representative of other bear species, reproductive performance will be inhibited in such an environment. In this study, we used the nonendangered American black bear (Ursus americanus) as the model for developing appropriate embryo transfer procedures. The donor bear mated numerous times between late May and early June. In late July we anesthetized her and used a series of telescoping sheaths to gain access to the uterus Then we passed a catheter through the largest sheath, inflated the balloon, and, using a 20-mL syringe, repeatedly infused into and then aspirated from the uterus PBS + BSA. We emptied the syringe into Petri dishes and observed 2 embryos. We rinsed the embryos, placed them in human tubal fluid + HSA + HEPES and then held them at 35 degrees C for 5 h. The recipient mated during mid-June; in late July we anesthetized her and, with the aid of laparoscopy, transferred an embryo into the cranial portion of the uterine horn ipsilateral to the ovary containing a CL. The recipient delivered 2 cubs in January. Necropsy results indicated that the neonates lived for 6 to 8 wk before succumbing to flooding in the den. The DNA from hair samples belonging to the neonates indicated that the male cub belonged to the donor, the female cub to the recipient. The delayed implantation mechanism in bears probably allowed for the successful development of the embryo in the presence of a substantial asynchrony between the donor and the recipient (13 d). We conclude that embryo transfer is possible in the American black bear and can lead to the birth of live cubs.

Topical aminocaproic acid significantly reduces the incidence of secondary hemorrhage in traumatic hyphema in the rabbit model.

Systemically administered aminocaproic acid has been shown to reduce the incidence of secondary hemorrhage after traumatic hyphema. To date, no topical treatment has been shown to be effective in reducing the incidence of rebleeding in a double-masked study. Experimentally induced traumatic hyphemas in the rabbit model were treated with topical placebo gel (4% carboxypolymethylene gel only) or carboxypolymethylene gel with amino-caproic acid (treated group) in a double-masked fashion and were compared with untreated controls (control group). In both the control and placebo groups, there was a 33% rebleed rate. The treated eyes had a 10% rebleed rate that is statistically significant. The topically applied aminocaproic acid gel appears to be well tolerated locally without evidence of systemic toxicity. This study indicates that topical aminocaproic acid may be an effective alternative to systemic treatment to reduce the incidence of secondary hemorrhage in traumatic hyphema.

Nucleoside conformations. XVII. A PMR study of 2'-anhydronucleosides and comparison with X-ray data.

A series of 2'-cyclo-nucleosides (2,2'-O-anhydro-uridine, -N(3)-uridine and cytidine and 8,2'-S-anhydro-guanosine) have been studied by PMR in DMSO and D(2)O. As expected these compounds are quite rigid, but their solution conformation is considerably different from that observed in single crystal x-ray studies. While the pyrimidine cyclonucleosides in the crystal form show a C(4')-endo conformation (pseudorotational phase angle P=212 degrees to 233 degrees ), their solution conformation is C(1')-exo (P=130 degrees to 138 degrees ) and the cyclothioguanosine shows a closely similar one (P=112 degrees ). Exocyclic rotamer distribution is different in the various compounds.