Biomedical subjects

R Taft

Publications and source records attributed to R Taft.

17 recordsLinked to original sources

PubMed2000

Increased expression of insulin-like growth factor binding protein-1 during induced regression of bovine corpora lutea.

Three experiments were conducted to examine gene expression during induced luteal regression in the cow; the initial purpose was the identification of potential embryotoxins. In experiment 1, changes in gene expression in the corpus luteum (CL) were identified by differential display reverse transcription-polymerase chain reaction (DD-PCR) during the first 72 h of luteal regression in cows treated with prostaglandin F(2alpha) (PGF(2alpha)) on Days 4-7 after estrus. Expression of insulin-like growth factor-binding protein-1 (IGFBP-1) was up-regulated, with greatest expression at 24 h (P < 0.05) after treatment with PGF(2alpha) began. In experiment. 2, IGFBP-1 and its mRNA were quantified in CL collected 24 or 48 h after treatment with PGF(2alpha) on Day 4 or 10 after estrus. Because local mechanisms for exchange of hormones between the ovary and uterus are known in ruminants, uterine flushings were assayed for IGFBP-1 to seek evidence of local transfer of luteal IGFBP-1 to the uterus. IGFBP-1 mRNA was increased (P < 0.05) in CL 24 h after treatment when PGF(2alpha) that began on Day 10, and by 48 h after treatment that began on Day 4. Concentrations of IGFBP-1 increased (P < 0.05) in a pattern similar to mRNA, by 24 h on Day 10, and by 48 h on Day 4. Concentrations of IGFBP-1 in uterine flushings did not change on either day. Concentrations of progesterone decreased (P < 0.05) by 8 h after treatment with PGF(2alpha) that began on Day 10, but not until 24 h after treatment that began on Day 4. In experiment 3, cows received either saline or PGF(2alpha) and CL were collected 2 or 10 h after a single treatment, or 2 h after a second treatment that was given 8 h after the first. Expression of IGFBP-1 was increased by 2 h after treatment with PGF(2alpha) on both Days 4 and 10 after estrus. In conclusion, secretion of IGFBP-1 is increased during luteolysis, and may inhibit the steroidogenic effects of insulin-like growth factor-I (IGF-I), but no evidence was found to implicate IGFBP-1 in the embryotoxic effect of regressing CL.

Animals↗

PubMed2000

Effect of the previously gravid uterine horn and postpartum interval on follicular diameter and conception rate in beef cows treated with estradiol benzoate and progesterone.

An experiment was performed to evaluate the effect of the side of ovulation with respect to the previously gravid uterine horn on fertility of cows inseminated at one of two periods postpartum. All cows were treated with an intravaginal progesterone insert for 7 d and received estradiol benzoate (2 mg, i.m.) at the time of device insertion, prostaglandin F2alpha (25 mg, i.m.) at the time of device removal, and estradiol benzoate (1 mg, i.m.) 30 h after device removal. All cows were inseminated 28 to 30 h after the second treatment with estradiol benzoate, regardless of observed estrus. Cows treated in Period 1 received inserts at 16 to 20 d postpartum and were inseminated at 25 to 29 d postpartum. Cows treated in Period 2 received inserts at 26 to 30 d postpartum and were inseminated at 35 to 39 d postpartum. Diameter of the largest follicle at insert removal was greater in cows treated in Period 2 (10.1 +/- 0.3; mm +/- SEM) than in cows treated in Period 1 (9.1 +/- 0.3; P < .05). Diameter did not differ with the side of ovulation in respect to the previously gravid uterine horn. Diameter was greater in cows 5 to 9 (10.3 +/- 0.3) than in cows 3 to 4 (9.0 +/- 0.3) or 10 to 13 (9.4 +/- 0.6) yr of age (P < .01). The proportion of cows that ovulated from the ovary contralateral to the previously gravid uterine horn was greater (P < .05) than of those that ovulated from the ipsilateral ovary, and the incidence of ovulation was reduced in cows 3 to 4 yr of age (P < .01). Conception rate tended to be greater for ovulation from the ipsilateral compared with the contralateral ovary, relative to the previously gravid uterine horn (P < .10) and for ovulation from the right than the left ovary (P < .06). Conception rate was less if cows ovulated a follicle that was < 9 mm than a follicle > or = 9 mm in diameter at insert removal (P < .01) and was greater in cows inseminated in June than in April or May (P < .05). In conclusion, in cows in which estrus was synchronized at 25 to 39 d postpartum, ovulation from either the ovary ipsilateral to the previously gravid uterine horn, or the right ovary, tended to increase fertility.

Animals↗

PubMed1996

The role of core biopsy in the diagnosis of mammographically detected lesions.

BACKGROUND: Both stereotactic imaging and ultrasound have been used to localize non-palpable breast lesions for core biopsy analysis. In particular, stereotactic core breast biopsy with a dedicated recumbent mammographic unit is an accurate and reliable technique, and this has been substantiated in a number of recent prospective studies comparing percutaneous core biopsy with open excisional biopsy. METHODS: This article reviews biopsies of 521 lesions from 502 cases using both stereotactic localization (469 lesions) and ultrasound (33 lesions). The types of breast cancer and benign breast disease diagnosed with core sampling are reviewed. In this series it was not intended to compare all the results of core biopsies with those of open excisional biopsy, but a subset group, which comprised certain benign lesions and malignancies, as well as lesions diagnosed on core biopsy in which the radiology and pathology did not correlate, was further evaluated and compared to the findings with open biopsy. The cases where there were differences in core and excisional biopsy diagnosis are discussed. RESULTS: In this series the benign to malignant ratio was 2.7:1, in other words, 27% of the lesions biopsied were malignant. The sensitivity for detecting cancer was 97% with the positive predictive value being 99%. CONCLUSIONS: This series further substantiates the accuracy of core biopsy. It is recommended that certain lesions diagnosed as benign on core biopsy histology should also proceed to open biopsy. Correlation between clinical findings, radiology and pathology further improves the reliability of core biopsy under imaging guidance.

Adenocarcinoma↗

PubMed1996

Exogenous pulses of luteinizing hormone cause persistence of the largest bovine ovarian follicle.

The objectives of this study were, 1) to determine whether increased frequency of LH pulses, independent of changes in progesterone, will cause persistence of the first largest ovarian follicle (LF1) during the bovine estrous cycle and 2) to determine whether a follicle produced in this manner will ovulate after luteal regression. In Exp. 1, 32 nonlactating beef cows were randomized into four groups. Bovine LH was given as 50 micrograms i.v. every 2 h from 0800 on d 7 through 0800 on d 13 postestrus to cows in two groups, which in addition either received PGF2 alpha on d 12 and were allowed to ovulate (LHOV; Group 1) or were ovariectomized (LHOVX; Group 2) on d 13. Cows in Group 3 received progesterone via a used controlled internal drug releasing device (CIDR) on d 4 to 13, PGF2 alpha on d 6, and ovariectomy on d 13. These cows received 1 mL of saline i.v. every 2 h on d 7 to 13, as did those in Group 4 (SAL), but cows in Group 4 did not receive any PGF2 alpha. Proportion (percentage) of LF1 maintained until d 13 was similar in cows with CIDR (100) and on LH (88) but less in cows on SAL (36; P < .01). The LF1 were largest in cows with CIDR, smallest in cows on SAL, and intermediate in cows on LH (P < .001). During d 7 to 13, progesterone was lesser and estradiol was greater in peripheral plasma in cows with CIDR than in cows on LH or SAL (P < .001). In Experiment 2, beef heifers received 50 micrograms of bLH (LH; n = 5) or saline (SAL; n = 4) i.v. every 2 h from 0800 on d 7 until 12 h after signs of estrus were observed following PGF2 alpha on d 12. The LF1 were maintained by LH and 60% ovulated; all LF1 were replaced during treatment in heifers on SAL. The LF1 were larger in heifers on LH, but estradiol and progesterone did not differ between groups. In conclusion, an increased frequency of LH pulses during a normal luteal phase allowed LF1 to persist but did not increase secretion of estradiol.

Animals↗

PubMed1991