Uterine infections are a major reproductive problem in livestock. We conducted two experiments to investigate factors that may modulate uterine responses to infectious bacteria. In Exp. 1, ewes received intrauterine inoculations of either saline or bacteria (75 x 10(7) cfu of Actinomyces pyogenes and 35 x 10(7) cfu of Escherichia coli) on either d 0 or 7 of the estrous cycle. Vena caval samples containing uteroovarian blood were collected twice daily from 12 h before until 6 d after inoculation. Only ewes inoculated with bacteria on d 7 developed infections. Basal (4.8 vs .4 pmol), lipopolysaccharide-stimulated (14.2 vs 6.1 pmol), and concanavalin A-stimulated (65.8 vs 21.6 pmol) blastogenesis (i.e., [3H]thymidine incorporation) of vena caval lymphocytes was greater (P < or = .002) for ewes inoculated with bacteria or saline on d 0 rather than on d 7. The number (per 100 white blood cells) of lymphocytes was greater (41.3 vs 30.8, P < .001) and that of neutrophils was less (42.5 vs 51.6, P < .001) in ewes inoculated on d 0 rather than d 7. Bacteria increased (P < .05) vena caval PGF(2 alpha) but not PGE2 concentrations. In Exp. 2, two protein fractions (molecular weights of > or = 100 kDa and approximately 12.7 kDa) from chromatography of uterine flushings collected on d 0 or 7, or 18 d after ovariectomy on d 0 or 7, modulated phytohemagglutinin-stimulated blastogenesis; the heavier fraction from d 0 had a stimulatory component, but the major effects of the fractions were inhibitory. The differences in immune function and regulation between d 0 and 7 probably explain how the uterus of follicular phase ewes was able to prevent the development of an infection.

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experiments designed to test the effect of carrier on the separation.Chemistry of Aqueous Uranium(V) Solutions. I. Preparation and Properties.Analogy between Uranium(V), Neptunium(V) and Plutonium(V)1

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reaction 1 occurs, in which thermal detrapping from the em-+ shallow trap est- (1) shallow trap occurs at temperatures above 90°K. At 4 and 77°K reaction 1 occurs only in the forward direction and est-apparently does not contribute to the epr spectrum of et-. The lack of epr is rationalized below. Thus there is no temperature dependence for et-photobleaching at 4 and 77°K. Above 77°K est-is thermally detrapped and at least some of the em-produced will be retrapped to form et-. This back-reaction explains the negative temperature dependence. At higher temperatures more retrapping to form et-occurs and decreases the net rate of et-loss.The fit to an Arrhenius plot in Figures 3 and 4 suggests that the average shallow trap depth is 1.2 kcal/mol (0.05 eV). The shallow-trap model implies that the photocurrent should show a positive temperature dependence corresponding to 0.05 eV. This has indeed been o b s e r~e d .~ The photocurrent data also show that the density of shallow traps is radiation dose dependent and therefore suggest that the shallow trap is associated with 0-. If so, one might expect similar shallow traps to be associated with other holes in the alkaline ice matrix. Figure 3 shows the same negative temperature dependence for photobleaching of etfrom photoionization of ferrocyanide ion as for radiation-produced et-. So, similar shallow traps appear to be associated with ferricyanide ion holes and 0-holes in the alkaline ice matrix. The epr spectrum of est-could well be broadened beyond detection by spinspin interaction with the holes. Table I shows that the fraction of et-that corresponds to 0loss on prolonged optical bleaching is nearly independent of temperature and radiation dose. At 150°K dielectrons are not thermally stable. l8 Thus competition between et-and 0-for em-does not determine the fractions in Table I. Likewise the thermal instability of est-precludes competition between 0-and shallow traps as the rationalization for Table I. The results seem to be tentatively explained by invoking two reactions of either em-or est-with 0which have temperature independent rates. One reaction must lead to loss of both 0-and the electron species and the other reaction must lead to loss of only the electron species. The latter reaction may be regarded as analogous to the reaction of photobleached electrons with TMPD+ in 3-methylpentane at 77°K which leads to loss of the electron optical spectrum but does not change the TMPD+ optical spectrum.l9 The product of such a reaction is unknown in detail, but one possible model is a hole-electron charge pair.Acknowledgment.Abstract: The hydrolysis of ethyl oxalate, -OzCCOzEt(EtOx-), is catalyzed by a variety of metal ions; the rate is given by the expression: rate = k8[EtOx-][M2+] [OH-]. The values of ka ( M F 2 sec-l) at 25" decrease with Mz' in the order Cuz+ (1.63 x 107) > Pb2+ (3.72 X 106) > Zn2+ (1.14 X lo5) > NiZ+ (6.81 X lo4) > CoZf (4.15 X lo4) > Mg*+ (1.02 X lo*). The data have been interpreted in terms of a mechanism [M2+ + EtOx-$ MEtOx+ (Kt); MEtOx+ + OH-...

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