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Biomedical subjects

L L Anderson

Publications and source records attributed to L L Anderson.

At least 163 records · Page 9Linked to original sources
PubMed1983

Relaxin production and release after hysterectomy in the pig.

Relaxin secretion by luteal tissue and into peripheral blood was examined in relation to changes in the fine structure of aging porcine corpora lutea. Sequential bleedings every sixth day reveal a similar increase in serum relaxin concentrations from days 6-114 in hysterectomized and pregnant gifts. The span of the estrous cycle is about 21 days, and the length of pregnancy is about 115 days in pigs. Estrone (E1) and 17 beta-estradiol (17 beta-E2) serum levels increase with placental development; after hysterectomy, they are low from days 12-168. In luteal tissue, peak quantities of relaxin and electron-dense granules occur on day 100 in hysterectomized and pregnant gilts. By day 112, luteal tissue relaxin levels and granule populations decrease by about half, while relaxin secretion into peripheral blood approaches peak concentrations about day 114 in hysterectomized as well as pregnant gilts. Between days 114 and 120, serum relaxin decreases by half even though the corpora lutea persist to day 150 in hysterectomized animals. Thereafter, cytoplasmic granules and blood and luteal tissue levels of relaxin decrease gradually to day 150 in hysterectomized gilts; in contrast, they disappear abruptly after parturition. In hysterectomized gilts, relaxin release coincides with diminished populations of granules in corpora lutea, and the initiation of these events seems to be precisely timed. E1 and 17 beta-E2 secretion is unrelated to relaxin secretion in pregnant and hysterectomized gilts. High peripheral blood levels of E1 and 17 beta-E2, primarily of placental origin, or even the presence of the uterus are not required in the release of relaxin at day 114. By using steroidogenic and protein synthetic capabilities of luteal cells as criteria essential to the evolution of reproduction in this species, the results presented here suggest that 114 days rather than 21 days characterize the reproductive cycle, even in the absence of the uterus. These results indicate that the production and, particularly, the release of relaxin into peripheral blood on about day 114 in hysterectomized gilts as well as pregnant animals may be genetically controlled.

Animals↗
PubMed1983

Serum profiles of LH, FSH and prolactin from 10 weeks of age until puberty in gilts.

To characterize the secretory patterns of luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) during prepubertal development of the gilt, blood samples were collected at 20-min intervals for 4 h once a week from four littermate gilts 10 to 18 wk of age and from another group of four littermate gilts 19 to 25 wk of age. Puberty occurred in the latter group during wk 25. Serum concentrations of LH, FSH and PRL were averaged for each 4-h sampling period within each gilt, and any single value greater than one standard deviation above the mean for that period was identified as a secretory spike. Mean LH was greater at 16 wk of age than during wk 11, 12 and 13, and serum LH levels were higher at 25 than 22 wk of age. Frequency and magnitude of LH spikes were greatest at 16 wk in the group of gilts 10 to 18 wk of age, but magnitude of LH spikes did not change from 19 to 25 wk. The frequency of FSH secretory spikes did not change in gilts from 10 to 25 wk of age. No changes in mean serum concentrations of PRL, frequency of PRL spikes and magnitude of PRL spikes were observed during prepubertal development. Spikes of FSH and PRL occurred with more than random synchrony throughout the study. Spikes of LH and FSH or LH and PRL were highly synchronized during early prepubertal development (10 to 18 wk), but less synchronized in gilts 19 to 25 wk of age.

Aging↗
PubMed1983

Growth hormone secretion after hypophysial stalk transection in pigs.

The level and pattern of growth hormone (GH) secretion were investigated in mature ovariectomized gilts after hypophysial stalk transection and sham operation. A nylon disk was inserted between severed ends of the stalk to prevent vascular regeneration. Blood samples were collected via indwelling jugular catheters at 15-min intervals for 3 hr, 2 days before surgery (Day -2) and 2 days after surgery (Day +2), and at 4-hr intervals from Day +3 to Day +8. Mean overall serum concentrations of GH after hypophysial stalk transection remained similar (P greater than 0.05) to presurgical levels. These mean concentrations also were similar to those in sham-operated and unoperated controls. However, hypophysial stalk transection significantly dampened (P less than 0.05) the episodic secretion of GH and resulted in elevated basal blood concentrations of the hormone as compared with either presurgical levels or those in the two control groups. These results indicate that synthesis and secretion of GH continue in the absence of hypothalamic control in hypophysial stalk-transected gilts. Thus, the hypothalamus is required for regulation of both episodic release and the tonic inhibition of basal secretion of growth hormone in the pig.

Animals↗
PubMed1982

Autopsy findings in squamous-cell carcinoma of the esophagus.

The findings at autopsy of 79 patients with esophageal carcinoma over a period of 15 years were reviewed. Five patients were free of tumor, and another seven had disease localized to the esophagus and other mediastinal structures. Sixty-seven (85%) had metastatic disease. The average number of metastatic sites per patient was 3.3. Most common metastatic sites were lymph nodes (73%), lung (52%), and liver (47%). The patients in this series had a higher incidence of metastases than those in other published series. Possible reasons for this discrepancy include race and sex differences between this population and those in previous reports, as well as the fact that this series includes very few postoperative deaths.

Adult↗
PubMed1982

Effect of porcine relaxin on cervical dilatation, pelvic area and parturition in beef heifers.

Purified porcine relaxin (3,000 U/mg) was administered either into the cervical os or by intra-muscular injection to crossbred beef heifers beginning 4 days before expected parturition, in an attempt to elucidate the physiological roles of relaxin in cervical dilatation, the pelvic area, and parturition. Relaxin (3,000 U in a gel vehicle), when administered into the cervical os during late pregnancy, induced significant dilatation of the cervix 8 and 16 h later, as compared to vehicle-treated controls. This induced cervical dilatation did not cause premature parturition in relaxin-treated heifers and was similar to controls. Exogenous relaxin during late gestation elicited an increased growth rate of the pelvic area, as determined by sequential measurements of height and width of the pelvic canal. These results indicate that, before parturition, pelvic width increased more rapidly than pelvic height and that exogenous relaxin elicited a greater response in both parameters. Highly significant nocturnal elevations in concentrations of progesterone in peripheral blood serum occurred in vehicle-treated control heifers during late pregnancy. These nocturnal elevations in serum levels of progesterone were significantly reduced after 8 and 16 h of relaxin treatment in experimental animals as compared to control heifers. The mechanisms by which porcine relaxin reduces ovarian progesterone secretion in beef heifers remain undefined.

Animals↗
PubMed1982

Quantification of receptors for estradiol-17 beta and progesterone in the pituitary and hypothalamus of prepubertal gilts induced to ovulate with pregnant mare's serum and human chorionic gonadotropin.

Nuclear and cytoplasmic exchange assays were developed and validated to quantify receptors for estradiol-17 beta (E217 beta) and progesterone (P4) in hypothalamic and pituitary tissues of gilts before, during, and after treatment with pregnant mare's serum (PMS) and human chorionic gonadotropin (hCG). Prepubertal gilts, 5 months old, were assigned randomly to four treatments. One group of gilts received 500 IU PMS (Day 0) and were sacrificed 2 days later (2 days post-PMS); another group received 500 IU PMS on Days 0 and 2, and were sacrificed 4 days from the initial injection (4 days post-PMS). A third group of gilts received PMS (500 IU) on Days 0 and 2, 1000 IU hCG on Day 4, and were sacrificed 5 days after hCG (5 days post-hCG). Controls were given saline on Days 0, 2 and 4 and sacrificed on Day 6. In pituitary tissues, there were no significant changes in numbers of cytoplasmic E2 17 beta receptors, cytoplasmic P4 receptors, nuclear P4 receptors or nuclear E2 17 beta receptors among the control, 2 days post-PMS, 4 days post-PMS or 5 days post-hCG treatment groups. In hypothalamic tissues, no differences in cytoplasmic E2 17 beta receptors, cytoplasmic P4 receptors or nuclear P4 receptors were found among any of the treatments. Nuclear receptors for E2 17 beta in hypothalamic tissues were greater, however, in gilts 2 days post-PMS (P less than 0.05) than in controls or 5 days post-hCG gilts, but they were not different from gilts 4 days post-PMS. Follicular development and serum concentrations of E2 17 beta followed the expected patterns after PMS; only ovaries from hCG-treated pigs contained corpora lutea. Because the PMS-hCG regimen simulated the onset of puberty, it seems that gilts attain puberty without a significant change in the number of receptors for E2 17 beta and P4 in the pituitary or hypothalamus.

Animals↗
PubMed1982

Quantification of Receptors for Estradiol-17 beta and progesterone in the pituitary and hypothalamus of gilts during prepubertal development.

To determine whether pituitary receptors for estradiol-17 beta (E217beta) and progesterone (P4) change during prepubertal development, receptors were quantified by nuclear and cytoplasmic exchange assays from Yorkshire gilts 1, 2.5, 4, and 5.5 months old. No significant differences in the concentration of cytoplasmic or nuclear E217beta receptors were found during these prepubertal ages. Likewise, no differences in the concentration of cytoplasmic or nuclear P4 receptors were found during the four ages tested. These results suggest that prepubertal gilts approach the onset of puberty without a significant change in the concentration of E217beta or P4 receptors in the pituitary gland. To determine whether hypothalamic receptors for E217beta or P4 change during prepubertal development, receptors were quantified in hypothalami removed from these same gilts. At 2.5 months of age, the concentration of E217beta receptors was less (P less than 0.01), but the physiological significance of this reduction is unclear. No significant differences in the number of hypothalamic nuclear E217beta receptors were found during these prepubertal ages. Likewise, no differences in the concentration of cytoplasmic or nuclear P4 receptors were found during the four ages tested. These results suggest that prepubertal gilts approach the onset of puberty without an increase in the concentration of E217beta or P4 receptors in the hypothalamus.

Aging↗
PubMed1982

Prolactin secretion after hypophysial stalk transection in pigs.

Hypothalamic regulation PRL secretion was investigated in 13 7-month-old Yorkshire gilts by comparing the effects of hypophysial stalk transection and sham operation. Ovariectomized gilts were fitted with an indwelling cannula in the anterior vena cava to determine sequential serum profiles of PRL secretion before, during, and 190 h after cranial surgery. A nylon disc was inserted between severed ends of the hypophysial stalk to prevent vascular and tissue regeneration; sham operations included all surgical procedures with exception of stalk transection and insertion of the disc. During a preoperative period of 120 min, PRL concentrations in peripheral serum remained consistently low [2.3 +/- 0.3 ng/ml (mean +/- SEM)] in all gilts. During 105 min of anesthesia (induced by thiamylal sodium and maintained by halothane and oxygen), PRL increased (8.2 +/- 1.9 ng/ml) in all gilts. Peak PRL values averaged 10.7 ng/ml at hypophysial stalk transection or sham operation and then declined steadily in both groups during the last 105 min of surgery. PRL remained elevated (P less than 0.002) in hypophysial stalk-transected gilts compared with sham-operated controls throughout a postoperative period from 6-190 h (3.7 +/- 0.4 vs. 1.9 +/- 0.2 ng/ml). These results indicate that basal secretion of PRL in the pig is inhibited by the hypothalamus.

Animals↗
PubMed1982

Growth, puberty and reproduction in gilts born to dams deprived of nutrients during pregnancy.

Reproductive performance through two gestations was evaluated in a random selection of gilts born to dams deprived of nutrients or full-fed during pregnancy. After weaning, gilts born to dams previously subjected to inanition during the middle third or last third of gestation (O kcal/d; water only; 40 d), and those born to full-fed (7.028) kcal/d) control dams throughout gestation were raised in the same outdoor lot. At approximately 150 d of age, the gilts were observed for estrous behavior and mated at the third estrus. Age at puberal estrus was earlier (P less than .01) for gilts born to nutrient-deprived dams. Gilts from control dams exhibited first estrus at 250 d, whereas puberal estrus in gilts born to dams deprived of nutrients during the middle or last third of pregnancy occurred at 208 and 219 d, respectively. Fifteen of 18 mated gilts from the nutrient-deprived dams remained pregnant to term, compared with seven of eight gilts from control dams. Birth weights of first-parity living neonates from gilts born to nutrient-deprived dams were similar to those of newborns from controls. First-parity litter weights at birth also were similar for the experimental and control groups. Litter size at birth of first-parity living neonates averaged 7.9 piglets for gilts born to nutrient-deprived dams and was similar (P less than .05) to that for gilts from full-fed controls (9.4 piglets). Second-parity pregnancy rate, birth weight, litter weight and litter size at birth and weaning were similar for all gilts born to nutrient-deprived and control dams. These results indicate that brief segments of maternal nutrient deprivation during middle or late pregnancy have little detrimental effect on subsequent growth and reproduction of the female progeny in this litter-bearing species.

Animals↗
PubMed1979

Maternal serum metabolites during prolonged starvation in pregnant pigs.

Pregnancies in pigs were sustained during periods of prolonged starvation in spite of maternal body weight losses exceeding 40 kg. Maternal stores of protein were made available for feto-placental development during starvation of the dam. Concentrations of maternal serum proteins, urea nitrogen, electrolytes, and iron were determined in sequential blood samples of healthy Yorkshire pigs during a prolonged period of 40 days inanition (water only) in either the middle third (days 30-70) or last third (days 70-110). Serum protein levels remained similar to full-diet controls throughout these two periods, whereas serum concentrations of albumin and urea N increased primarily during the last third of gestation in starved dams. Serum Na+ levels declined during prolonged inanition while Ca2+ increased and K+ remained unchanged. It was only near term that Fe2+ levels decreased in those dams starved during a period of 40 days in the last third of pregnancy. These results indicated that maternal serum components were sustained at adequate levels to maintain normal development of conceptuses during prolonged starvation in either the middle third or last third of pregnancy in the pig.

Animals↗