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Biomedical subjects

J F Kavanaugh

Publications and source records attributed to J F Kavanaugh.

At least 19 recordsLinked to original sources
PubMed1995

Effect of accessory sex gland fluid from bulls of differing fertilities on the ability of cauda epididymal sperm to penetrate zona-free bovine oocytes.

The ability of accessory sex gland fluid to affect the fertility of cauda epididymal sperm was evaluated for 10 bulls that ranged in fertility from 6.2% below to 6.0% above the average fertility of bulls at artificial breeding cooperatives. Cauda epididymal sperm collected from indwelling vasa deferentia catheters and cauda epididymal sperm exposed to accessory sex gland fluid from the same bull were compared on the basis of their rates of in vitro penetration of zona-free oocytes after heterospermic insemination. Incubation of cauda epididymal sperm with accessory sex gland fluid significantly enhanced the ability to penetrate oocytes, and bull fertility affected the magnitude of this improvement. For bulls of average and higher fertility, the positive influence of accessory sex gland fluid on penetrating ability of sperm was highly significant (p < 0.0001). Accessory sex gland fluid from bulls of below-average fertility also improved the penetrating ability of cauda epididymal sperm, although not significantly (p = 0.07). Heterospermic competitions compared the penetrating ability of cauda epididymal sperm exposed to homologous accessory sex gland fluid with a portion of the same sperm population incubated in heterologous accessory sex gland fluid from a bull of contrasting fertility. In experiments involving sperm from 12 different bulls, paired in 42 fertile/subfertile combinations, samples of cauda epididymal sperm mixed with accessory sex gland fluid from the higher-fertility bulls had greater oocyte-penetrating ability than when aliquots of that sample were mixed with accessory gland fluid from lower-fertility bulls (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Hemodynamics and wall shear rate in the abdominal aorta of dogs. Effects of vasoactive agents.

Vasoactive drugs are known to affect impedance (pressure/flow) and vessel wall motion in arteries. The nonlinear theory of oscillatory flow in straight elastic vessels indicates that wall shear rate is affected by changes in impedance phase angle and wall motion. To test whether wall shear rate depends on impedance phase angle and wall motion in vivo, wall shear rate was measured in the abdominal aorta of anesthetized dogs by using a flush-mounted hot-film anemometer, and the hemodynamic state was characterized by pressure, flow, and vessel dimension measurements. Vasodilators (nitroprusside and isoproterenol) and vasoconstrictors (angiotensin II and norepinephrine) were administered acutely, and the responses of wall shear rate and hemodynamics were determined. In the control state (no drugs), peak wall shear rate was 1835 +/- 153 s-1 (mean +/- SEM). The vasodilators induced large increases in impedance phase angle and wall motion concomitant with large increases in peak wall shear rate (62.4 +/- 20.4% for nitroprusside and 68.9 +/- 28.3% for isoproterenol), which were not predicted accurately by Womersley's theory of oscillatory flow in a rigid vessel or the nonlinear theory of oscillatory flow in an elastic vessel, with measured flow and vessel dimension used as inputs. The vasoconstrictors induced small decreases in impedance phase angle and wall motion and small changes in peak wall shear rate (increase, 30.5 +/- 8.0% for norepinephrine; decrease, 18.2 +/- 7.1% for angiotensin II), which were predicted accurately by Womersley's theory. The present study shows that vasoactive drugs, particularly vasodilators, can have significant effects on wall shear rate (stress) in the abdominal aorta that appear to be related to changes in impedance phase angle and vessel wall motion. However, the effects on wall shear rate are not predicted accurately by straight-tube theory.

Angiotensin II↗
PubMed1991

Binding and bioactivity of ovine and porcine prolactins in porcine mammary tissue.

Differential binding of homologous and heterologous prolactin was investigated in porcine mammary tissue. Specific binding of ovine prolactin to porcine mammary membranes or tissue slices was significantly greater than specific binding of the homologous porcine prolactin. Ovine prolactin was also more potent than porcine prolactin in stimulating proliferation of Nb2 cells. In contrast, stimulation of glucose metabolism in porcine mammary explants by porcine prolactin was greater than that by ovine prolactin. Differences in specific binding were probably not due to damage during iodination, as low concentrations of iodinated prolactins were similar to unlabelled prolactins in their abilities to stimulate proliferation of Nb2 cells. Furthermore, electrophoretic analysis of medium from binding reactions suggested that differences in specific binding were not due to proteolytic cleavage of the homologous prolactin into large (greater than 10 kDa) fragments. These studies suggest that ovine prolactin either binds to sites in addition to the authentic lactogenic receptor in porcine mammary tissue or that a significantly higher affinity of ovine prolactin for the porcine lactogenic receptor has little effect on its biological activity.

Animals↗
PubMed1989

Changes in phospholipids, cholesterol and protein content of oviduct fluid of cows during the oestrous cycle.

The oviducts of 4 cows were cannulated and oviduct fluid was collected daily from the exteriorized cannulas for a total of 5 oestrous cycles. Daily serum samples were assayed for oestradiol-17 beta and progesterone to monitor the oestrous cycle. Data for each cycle were compared for oviduct fluid collected during the non-luteal phase (serum progesterone less than or equal to 1.5 ng/ml) and the luteal phase (serum progesterone greater than 1.5 ng/ml). During the non-luteal phase oviduct fluid volume was higher and the osmolality was lower than during the luteal phase. Total protein, cholesterol and phospholipid secreted daily was greater during the non-luteal phase. Cholesterol and protein concentrations were generally lower during the non-luteal phase, but phospholipid concentrations were generally higher. About 40% of the phospholipid in oviduct fluid was phosphatidylcholine and lysophosphatidylcholine, while phosphatidylinositol and lysophosphatidylinositol accounted for 20%. The ratio of 1-acyl-phospholipid to diacylphospholipid increased during the non-luteal phase. An increased cholesterol to phospholipid ratio, and a decreased cholesterol to protein ratio in oviduct fluid also were associated with the non-luteal phase. Changes in the lipid composition of oviduct fluid during the oestrous cycle may play a role in the preparation of gametes for fertilization.

Animals↗
PubMed1989

Relationships among prolactin binding, prolactin concentrations in plasma and metabolic activity of the porcine mammary gland.

The current studies were designed to investigate relationships among prolactin (PRL) binding, PRL concentrations in plasma and metabolic activity of porcine mammary glands. Preliminary studies revealed specific high-affinity binding of oPRL to porcine mammary gland. Conditions for optimal specific binding were similar to those observed for other species. To address the main objectives of the study, four mammary biopsies and blood samples were obtained from each of four gilts during lactogenesis and lactation (d-11, 4, 21 and 42 of lactation) to measure in vitro rates of metabolic activity, PRL binding to mammary membranes and PRL concentrations in plasma. Metabolic activity, as measured by oxidation of glucose or acetate to CO2 and incorporation into lipid, was low during pregnancy, increased two- to five-fold on d 4, and then paralleled the lactation curve for sows. There were highly significant positive correlations between PRL binding and all measures of mammary metabolism when data from pregnancy and lactation were utilized. Coefficients were positive but generally not statistically significant when lactation data only were utilized. During lactation, significant negative correlations were observed between concentrations of PRL in plasma and PRL binding and between PRL in plasma and mammary metabolic rate. These data provide evidence that binding of PRL to its receptor is an important effector of milk production in sows. Furthermore, oPRL is a suitable ligand to quantify PRL binding to porcine mammary tissue.

Animals↗
PubMed1988

Bovine oviductal cannulations.

Oviductal fluid was collected from 23 dairy cows following cannulation of the oviduct in 38 procedures utilizing silastic catheters. Standing laparotomy in the caudal abdomen enabled exteriorization of the ipsilateral ovary, oviduct, and uterine horn tip. A simple plastic device inserted through the ostium facilitated placement of an indwelling catheter. The exteriorized catheter connected to a collection device attached to the flank that provided ready access for harvesting fluids. Typical fluid volumes collected ranged from 0.1 to 3 mL per day depending on the estrus cycle stage. Patency varied from 2 to 156 days with an average duration of 68.2 days. Fluid flow ceased most commonly when a catheter was avulsed from the surgical site (58%) or became occluded with fibrin (14%). Slight modification of the stanchion housing has increased the longevity of the preparations.

Animals↗
PubMed1987

Plasma somatotropin response to exogenous growth hormone releasing factor in lambs.

Two experiments were performed to examine the ability of human pancreatic growth hormone releasing factor (hGRF) administration to stimulate endogenous growth hormone (GH) secretion in lambs. Each study utilized eight Dorset wether lambs in replicated 4 X 4 Latin square experiments. Growth hormone response (integrated area under the curve for 150 min post-injection) for 0, 1, 5 and 10 micrograms hGRF/kg body weight averaged 13, 23, 92 and 134 units, respectively. While the 1-microgram hGRF dose was not different (P greater than .05) than the response to saline injection, there was an increased (P less than .01) GH response to 5 or 10 micrograms hGRF. Overall the GH response increased in a log dose-response fashion. There was distinct variation between lambs in their response to hGRF. Study II examined the optimal method to administer 40 micrograms hGRF/kg body weight to maximize GH concentration over 24 h. Continuous infusion (CI) was compared with eight (8X), four (4X), or two (2X) injections/d. Hourly blood samples were obtained from all lambs. Growth hormone response (area under the curve for 24 h) was 162, 305, 306 and 220 units for CI, 8X, 4X and 2X, respectively. Growth hormone response to CI was inferior to discrete injections, and the GH response to 4X or 8X was superior to 2X/d. Results demonstrate that, in spite of lamb-to-lamb variation, one can utilize exogenous hGRF to enhance GH secretion in lambs. Thus, the ability of exogenous hGRF to enhance growth performance merits further study.

Animals↗
PubMed1985

Effects of feeding, fasting and refeeding on growth hormone and insulin in obese pigs.

This study has indicated that temporal patterns of plasma GH changes were similar in lean and obese pigs with one to two secretory spikes occurring during a 6-hour period. Fasting caused increased GH in both pig strains; however, obese pigs, compared to lean, had lower GH during feeding and fasting. This depressed plasma GH of obese pigs may not be due entirely to impaired pituitary function since refeeding caused increased GH to levels similar to lean pigs. Insulin response per unit of feed intake was greater in obese pigs compared to lean. Together with higher insulin to glucose ratios, these results indicate hyperinsulinemia in the obese pigs. Overall, hormone and glucose responses were influenced by the nutritive status--fed, fasted or refed. Therefore consideration of feeding schedule was important in assessment of hormonal differences between the lean and obese pigs.

Animals↗
PubMed1985

Effect of partial stepwise luteectomy in pregnant gilts on maternal and fetal concentrations of progesterone.

The number of corpora lutea (CL) in gilts was reduced to 8, 5, and 3 on Days 30, 40, and 50 of gestation, respectively. In a second group of gilts the number of CL was reduced to 5 by luteectomy by Day 50. Luteectomy did not affect concentrations of progesterone (P) in maternal uterine or fetal umbilical vessels sampled at Day 80. Concentration of P was higher in umbilical than uterine plasma in all treatments (P less than 0.01). The uterine arterial-venous (A/V) difference in concentrations of P was positive and the umbilical A/V difference was negative in all groups. The uterine and umbilical A/V differences at Day 80 decreased as the number of CL decreased. Fetal survival was reduced in luteectomized gilts. These results indicate that gradual reduction of numbers of CL does not result in placental secretion of P into the maternal circulation but does alter the uptake of P by the uterus and umbilical circulation.

Animals↗
PubMed1983

Concentrations of progesterone in arterial and venous plasma of fetal pigs and their dams in late gestation.

Blood samples were drawn from uterine arteries and veins of pregnant gilts and from the umbilical artery and vein of each of their fetuses during laparotomy at Day 80. Concentrations of progesterone (P) were greater in fetal than maternal plasma. Uptake of P from the placenta by the fetal blood was evident but was not equivalent to the maternal uterine arterial-venous difference in P concentration. No correlation between plasma P and fetal weight was noted. Concentrations of P in both umbilical vessels of female fetuses were higher than in male fetuses. These data indicate that fetal sex affects the rate of transport and/or synthesis of P in the utero/placental compartment and/or the rate of metabolism of P in the fetus. The relative importance of de novo synthesis and transplacental transport of P in establishing concentrations of P in fetal blood remains to be elucidated.

Animals↗
PubMed1982

Glucose turnover in fast-growing, lean and in slow-growing, obese swine.

Glucose turnover and associated measurements were compared in genetically obese, slow-growing feral pigs (Ossabaw) and domestic lean, fast-growing (Yorkshire) pigs. Five Ossabaw and five Yorkshire pigs 8 wk of age were prepared with indwelling arterial catheters to facilitate injection of tracer and serial sampling of blood. After a 14-h fast, pigs were administered 100 muCi of glucose-6-3H in a single injection; 12 blood samples were obtained over the subsequent 4-h period to obtain tracer dilution curves. Plasma glucose concentrations were the same in both strains (88 mg/100 ml) prior to tracer injection and remained constant for the duration of the 4-h sampling period. Ossabaw pigs exhibited a smaller minimal glucose mass (144 vs 179 mg/kg body weight, P less than .01) and space (16 vs 20%, P less than .01) when compared with Yorkshire pigs. Glucose replacement rate was greater for Ossabaw pigs than for Yorkshire pigs (3.96 vs 2.97 mg.min-1.kg-1 body weight, P less than .001). Minimal transit time was less in Ossabaw pigs than Yorkshire pigs (36 vs 60 min, P less than .001), which reflected the greater rate of irreversible disposal of tracer from the glucose pool of Ossabaw pigs. In conclusion, under these experimental conditions and at similar fasting glucose concentrations, glucose turnover and metabolic clearance rates were greater in Ossabaw than Yorkshire pigs. The results suggest a greater rate of fasting liver gluconeogenesis during short-term fasting in the young Ossabaw than the Yorkshire pig.

Animals↗
PubMed1980

Effect of intraportal and continuous intrajugular administration of insulin on feeding in sheep.

The effect of intraportal and intrajugular administration of insulin on feed intake and on glucose and insulin of jugular blood was studied. Ad libitum intake of four wethers was measured and jugular blood was sampled at various times after intraportal administration of the treatments and meal initiation. The treatments injected in the first experiment were saline, 2 mU, 4 mU and 6 mU insulin/kg body weight (BW), and in a second experiment were saline, 2 mU, 6 mU and 12 mU insulin/kg BW/minute infused over a 15-minute period. Feed intake was depressed only by 15-minute intraportal infusion of the 2 mU and 6 mU doses. Plasma insulin was elevated at 5 minutes after injection of 4 mU and 6 mU insulin/kg BW, and elevated at 5 and 15 minutes after 15-minute infusion of all three treatments; plasma glucose was not affected. Two additional experiments used four wethers in which jugular blood was sampled during a 24-hour intrajugular infusion of insulin. The combined treatments were saline, 0.02 mU, 0.2 mU, 2 mU and 6 mU insulin/kg BW/minute. The 6 mU dose stimulated feed intake, 2 mU increased plasma insulin and both 2 and 6 mU depressed plasma glucose. Thus, the site, timing and amount of exogeneous insulin administration may cause varying feed intake responses. The results are discussed with respect to a possible role of insulin in appetite control in sheep.

Animals↗
PubMed1977

Changes in portal blood metabolites and insulin with feeding steers twice daily.

Four Holstein steers surgically prepared with a device for sampling from the portal vein were used to examine changes in concentrations of metabolites and insulin in portal blood with scheduled meals. The animals were fed a complete mixed ration (3.4 kcal/g digestible energy) twice daily at three intakes. Blood was sampled at 30, 15, 10, and 5 min before feeding and at 1, 3, 5, 10, 15, 30, 45, 60, and 120 min after feeding began. Average intakes of food at 30 min for the three intakes were 0 (control), 889 g (restricted), and 1425 g (fed). Packed cell volume increased rapidly within 15 min of initiation of the meal in fed steers, but the maximum change from pre-feeding was 6.6%. Insulin increased within 5 min with the restricted intake and at 15 min in fed steers. Portal volatile fatty acids and beta-hydroxybutyrate also increased within 15 min of initiation of the meal in fed steers, and glucose tended to decrease after feeding. Certain metabolites and insulin of portal bood changed rapidly with feeding. Additional studies are required to establish any role of these blood components in the short-term control of feed intake in steers consuming concentrate feeds.

Animal Feed↗
PubMed1977

Serum hormones in the perinatal pig and the effect of exogenous insulin on blood sugars.

Growth hormone (GH), insulin, cortisol, triiodothyronine (T3) and thyroxine (T4) were determined in serum of fetal pigs at 90, 100, 110 and 114 days of gestation and of newborn pigs at 1 and 24 hours of age. Fetal GH, T3 and cortisol increased between 90 and 110 days. GH concentration decreased between 110 and 114 days, while T3 and cortisol were unchanged. T4 was variable in fetal pigs and no relationship with T3 levels was apparent. Fetal insulin was constant at approximately 10 muU/ml. In newborn pigs there was a 3-fold and 2-fold increase in T3 and T4, respectively, during the first 24 hours of life. Cortisol in serum more than doubled during the first hour. Between 1 and 24 hours, there was a simultaneous decrease in cortisol and a 6-fold increase in insulin. No significant change in GH was noted during this time. Intraperitoneal insulin injected one hour before sacrifice induced a hypoglycemic response in newborn pigs, but not in fetal pigs.

Animals↗