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Biomedical subjects

L R French

Publications and source records attributed to L R French.

At least 37 records · Page 2Linked to original sources
PubMed1982

Effects of the uterus and mid-pregnancy conceptus on luteal lifespan of the rat.

Hysterectomy on or after Day 10 resulted in a quick return of pseudopregnant rats to oestrus but the interval to oestrus in pregnant rats was significantly longer (P less than 0.01), indicating that the gravid uterine horn interfered with uterine-induced luteolysis by Day 10. When pseudopregnant rats were injected with extracts of conceptuses or pregnant rat serum (PRS), samples collected on Days 10 or 12 of pregnancy delayed the return to oestrus (P less than 0.01 for conceptus extracts, P less than 0.05 for PRS) and serum progesterone concentrations on Day 13 of pseudopregnancy were higher (P less than 0.01) than in controls. Bioassays utilizing mammary development or inhibition of oestrus in virgin cyclic rats as endpoints failed to detect lactogenic activity in Day 10 conceptus extracts or PRS, and radioreceptor assays using bovine prolactin (NIH-B5) as a standard showed that Day 10 extracts had only about 2--3% of the lactogenic activity found in Day 12 extracts. Injections of dilutions of Day 12 extracts with 2 or 4 times the lactogenic activity as Day 10 extracts did not extend pseudopregnancy. These results suggest that by Day 10 the conceptus produces a factor capable of interfering with luteolysis and that this factor is not placental lactogen.

Animals↗
PubMed1982

Plasma concentrations of progesterone and 13,14-dihydro-15-keto prostaglandin F-2 alpha in pregnant, pseudopregnant and hysterectomized pseudopregnant mice.

Hysterectomized pseudopregnant mice had plasma progesterone concentrations on Days 6, 8, 10 or 12 after mating that were greater (P less than 0.05) than those of intact pseudopregnant mice and lower (P less than 0.01) than those of pregnant mice. Concentrations of 13,14-dihydro-15-keto-prostaglandin F-2 alpha on Days 6, 7, 8, 9 or 10 after mating were lower (P less than 0.05) in pregnant and higher (P less than 0.01) in intact pseudopregnant mice than in hysterectomized pseudopregnant mice. The results support the conclusion that there are uterine and extra-uterine luteolytic mechanisms which are mediated by prostaglandin and are perhaps functional by Day 6 of pregnancy.

Animals↗
PubMed1981

Uterine specific antigens in the ewe.

Uterine flushings from ewes on days 0, 3, 6, 9, 12 and 15 of the estrous cycle were analyzed for total protein content. Flushings from days 9, 12 and 15 had greater (P<.01) amounts of protein than those from 0, 3 and 6. Antisera to uterine fluids from ewes at day 10 to 12 or day 14 to 15 of pregnancy detected two uterine-specific antigens in uterine flushings at day 7, 11 and 15 but not at days 0 and 3 of the cycle. A third uterine antigen was also detected in kidney tissue extracts. All three antigens were present in endometrial extracts at each stage examined. Progesterone, or estrogen plus progesterone, administration to ovariectomized ewes induced the appearance of the two uterine-specific antigens. The third antigen was detectable even in ovariectomized ewes. No pregnancy-specific antigens were detected in flushings from days 7, 11 or 15 of gestation. The effect of pregnancy on endometrial protein synthesis was examined in vitro . No differences were seen in the incorporation of (3)H-leucine in day 11 pregnant or nonpregnant or in day 14 pregnant or nonpregnant endometrium. No differences in total uterine lumenal protein were observed. Endometrial secretions, obtained by conditioning media with endometrial explant cultures, were evaluated to assess their effect on protein synthesis in day 11 embryos cultured in vitro . No significant effects of endometrial secretions or serum were observed.

Journal Article↗
PubMed1981

Effects of antibodies to progesterone on reproduction of ewes.

Two experiments were conducted to determine the effects of immunization of ewes with progesterone-11alpha hemisuccinate coupled to bovine serum albumin (P-BSA) on estrous cycles, serum progesterone and fertility. In experiment I, ewes were immunized during the first estrous cycle in September and observed through January. Immunization against progesterone increased (P<.01) the proportion of estrous cycles of abnormal length. Two general patterns were evident in the ten ewes which were immunized against progesterone: 4 continued to show cyclic patterns of estrous activity throughout the experimental period and 6 entered periods of anestrus characterized by presence of corpora lutea. Apparent, aberrant, estrous activity and shortened luteal phases were also observed in ewes which were immunized against progesterone. In experiment II, immunization against progesterone caused serum progesterone concentrations to be 4 to 8 times higher (P<.01) than ewes which were immunized against bovine serum albumin. Fertility was reduced (P<.01) by immunization with P-BSA. In experiment II, immunization against progesterone shortened (P<.01) the second estrous cycle post-immunization, and at day 13 of the third cycle corpora lutea in P-BSA-immunized ewes were regressing and were lighter (P<.05) than in ewes which were immunized with bovine serum albumin.

Journal Article↗
PubMed1979

Effect of age and parity on litter size in pigs.

Litter size increased (P less than 0.01) as the age of the dam at farrowing increased. However, previous reproductive experience (parity) had no direct effect on litter size of dams of the same age.

Animals↗