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Biomedical subjects

J A Fitzgerald

Publications and source records attributed to J A Fitzgerald.

At least 19 recordsLinked to original sources
PubMed1997

Influence of a methanogenic flora on the breath H2 and symptom response to ingestion of sorbitol or oat fiber.

BACKGROUND AND OBJECTIVES: We investigated the possibility that a variant of the normal colonic flora, a high concentration of methanogens, influences the host's response to ingestion of nonabsorbable, fermentable materials. METHODS: To better evaluate symptomatic and breath H2 and methane (CH4) responses, subjects were placed on a basal diet (primarily rice and hamburger) that contained minimal amounts of nonabsorbable, fermentable substrate. A breath CH4/H2 ratio of greater or less than 1 on the second day of the basal diet was used to categorize subjects as high (N = 9) or low (N = 25) CH4 producers. After stabilization of the breath gas excretion (day 3 or 4 on the basal diet), the subjects ingested either sorbitol (8.8 g) or oat fiber (10.2 g). RESULTS: The low CH4 producers had a significantly higher (p < 0.05) breath H2 concentration than the high producers on the basal diet and after ingestion of sorbitol (27.1 +/- 2.7 ppm vs 15.8 +/- 3.6 ppm) or oat fiber (13.1 +/- 0.08 ppm vs 9.6 +/- 1.2 ppm). Low producers of methane reported significantly increased bloating and cramping after sorbitol ingestion and increased bloating after fiber ingestion, whereas high CH4 producers reported no significant increase in these symptoms. CONCLUSION: The presence of a methanogenic flora is associated with a reduced symptomatic response to ingestion of nonabsorbable, fermentable material in healthy subjects. Manipulation of the normal flora could be of therapeutic value in nonmethanogenic patients with irritable bowel syndrome.

Avena↗
PubMed1996

Endocrine correlates of partner preference behavior in rams.

We studied a unique group of rams that would not mate with estrous ewes during extensive testing for sexual behavior. The same rams courted males in preference to females in 30-min sexual preference tests and were classified as male-oriented (n = 6). We compared the following endocrine profiles: systemic steroid concentrations, the capacity of the testes to biosynthesize 17 alpha-hydroxyprogesterone and testosterone from 3H-progesterone in vitro, and the levels of brain aromatase activity (AA) in male-oriented rams vs. rams that were proven breeders and designated as female-oriented (n = 7). After the last behavioral test, sera were collected, and males in each experimental group were killed. Brains and testes were obtained for subsequent determinations of AA and measurements of steroidogenic enzyme activity. All dissections and subsequent assays were performed without knowledge of experimental group assignments. Serum concentration of testosterone (T), dihydrotestosterone (DHT), androstenedione, estrone (E1), and estradiol-17 beta (E2) were determined by RIA. AA was quantified by a 3H2O assay validated for neural tissue of the ram. We studied frontal, parietal and cingulate cortex, cerebellum, hippocampus, olfactory bulb, septum, amygdala, infundibulum-median eminence, and preoptic area (POA). Serum T, E1, and E2 concentrations of female-oriented subjects were significantly higher (p < 0.05) than those in male-oriented subjects (SEM: 1559 +/- 228, 46 +/- 2, and 15 +/- 3 pg/ml vs. 874 +/- 196, 40 +/- 2, and 8 +/- 1 pg/ml serum, respectively). DHT and androstenedione concentrations in the systemic circulation did not differ between groups. Likewise, biosynthesis of labeled T and 17 alpha-hydroxyprogesterone from 3H-progesterone by testicular homogenates in vitro was significantly higher (p < 0.05) in female-oriented than in male-oriented subjects (28.8 +/- 8.1 vs. 12.1 +/- 2.3 mumol.h-1.mg protein-1 for T and 416.9 +/- 100.8 vs. 186.3 +/- 30.7 mumol.h-1.mg protein-1 for 17 alpha-hydroxyprogesterone). The highest level of AA was found in the POA, which was significantly greater in female-oriented than in male-oriented rams (472 +/- 34 vs. 296 +/- 24 fmol 3H2O.h-1.mg protein-1, p < 0.05). AA in other brain areas did not differ between experimental groups. Our data suggest that the testes of the male-oriented ram have reduced capacity for T production. In other species, T controls in situ estrogen formation not only by providing substrate for aromatization but also by up-regulating P450arom mRNA in the POA. Because the POA is part of a neural circuitry that mediates male sexual behavior in many species, we hypothesize that the capacity for aromatization influences sexual orientation of these rams.

17-alpha-Hydroxyprogesterone↗
PubMed1996

Effect of selection for lifetime production of lamb weaned on hormonal factors that affect growth in Targhee ewes and lambs.

Targhee ewes (n = 22, average age 5 yr) rearing twin lambs were used to investigate serum growth hormone (GH), IGF-I, triiodothyronine (T3), thyroxine (T4), and prolactin (PRL; ewes only) concentrations associated with selection pressure for lifetime production of kilograms of lamb weaned per ewe. Period 1 started on d 4 after birth and was conducted in confinement. Periods 2, 3, and 4 were conducted on fenced intermountain sagebrush-bunchgrass range starting at an average of 49, 84, and 112 d after birth, respectively. Blood samples were collected hourly for 6 h on d 4, 11, 18, 25, 49, 84, and 112 after lambing. Ewe models included the fixed effect for line, with ewe age, lambing date, and starting weight nested within line as potential covariables. Lamb models included fixed effects for line, sex, and sibling sex, with lamb age and birth weight nested within line tested as possible covariables. Growth hormone concentrations were greater (P = .06) for selected than for control ewes, but lamb GH concentrations did not differ (P = .90) between selected and control lambs. Ewe prolactin concentration tended (P = .13) to be greater for control than selected ewes. Ewe and lamb IGF-I did not differ (P > .55) between selected and control ewes and lambs. Ewe T3 and T4 concentrations did not differ (P > .19) between selected and control ewes; however, lamb T3 and T4 concentrations were greater (P < .01) for control than for selected lambs. Increased GH concentration in selected ewes seemed to be associated with greater milk production. Differences in selected and control lamb T3 and T4 concentrations could be an indicator of receptor sensitivity, metabolic activity, or seasonal reproductive transitions in ewe lambs.

Aging↗
PubMed1995

A comparison of LH secretion and brain estradiol receptors in heterosexual and homosexual rams and female sheep.

This study examined endocrine components of sexual orientation of male sheep. Sexual orientation of adult rams was identified through standardized sexual performance tests. Four rams that copulated with ewes, four rams that never mounted females and copulated with males, and eight ewes were used in the experiments. Exogenous estradiol benzoate (50 micrograms, i.m.) stimulated (P < .05) a preovulatory-like LH surge 16-22 hr after administration to females. Estradiol did not (P > .05) affect LH release of heterosexual or homosexual rams. Thirty days after the estradiol challenge, sheep were euthanized and areas of the amygdala (AMY), hypothalamus (HYP), anterior pituitary (AP), and preoptic area (POA) of the hypothalamus were collected. Occupied and unoccupied content of estradiol receptors (ER) was determined. The content of ER in the amygdala of both homosexual rams and ewes was similar, but less than (P < .05) the content of ER in heterosexual rams. The ER content measured in other brain regions did not differ by sex or orientation. In summary, results from these data show that the preovulatory LH surge mechanism that is a characteristic of the female does not occur in either homosexual or heterosexual rams. Conversely, the ER content of the AMY of homosexual rams is similar to that of ewes and differs from the heterosexual male. Differences in ER content between heterosexual and homosexual rams imply that the amygdala serves as a link for input from potential mates. These data suggest that the amygdala not only plays a role in sexual behavior but may be involved in sexual orientation of rams.

Animals↗
PubMed1994

Effect of morphine and naloxone on LH response and sexual behavior of rams (Ovis aries).

Effects of the opiate agonist, morphine, and antagonist, naloxone, on LH release, courtship behavior and ejaculation frequency of mature, sexually active or sexually inactive rams were investigated. Plasma LH concentrations were monitored from blood samples collected every 15 min for 10 hr (0800 to 1800 hr) from eight rams that were isolated from or in contact with estrous females. Plasma LH concentration was higher (P < .05) in sexually active rams exposed to receptive females compared with hormone concentration of rams isolated from ewes. Intravenous infusion of morphine sulphate (1 mg/kg) into rams 4 and 6 hr after exposure to ewes reduced (P < .05) plasma LH concentration as compared to rams given saline. Morphine did not affect (P > .05) courtship behavior (investigatory sniff, mount attempt, foreleg kick, flehmen, vocalization) but diminished (P < .05) number of ejaculations. In another trial, LH concentrations were higher (P < .05) in seven sexually active rams given naloxone iv or when given to three rams through an intracerebroventricular cannula (icv) as compared to LH response of sexually inactive rams. LH did not differ (P > .05) in seven sexually inactive rams before or after administration of naloxone. Investigatory sniffs by sexually active rams were increased (P < .03) after treatment with the opiate antagonist. Four of the seven sexually active rams had more ejaculations after naloxone compared with the pretreatment period, but mean ejaculation frequency after treatment did not differ (P = .31). Naloxone did not stimulate courtship behavior of sexually inactive males.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The behavioral component of the ram effect: the influence of ram sexual behavior on the induction of estrus in anovulatory ewes.

The objective of this study was to test whether the sexual behavior of the ram affects the ram effect. Rams exhibiting either high (HP) or low (LP) levels of sexual performance (on the basis of serving capacity tests) were exposed to 89 anestrous ewes for 28 d. Thirty-two anestrous ewes were not exposed to rams. The objective of this study was to compare the efficacy of estrus induction by HP (n = 4) vs LP (n = 4) rams. Plasma progesterone concentration was used as an index of ovarian activity. Groups of ewes were exposed to either an HP or an LP ram in a .32-ha pasture. Courtship behaviors of rams were recorded for 6 h on the initial day of exposure and for 30-min periods on alternate days thereafter. A greater percentage of ewes exposed to HP rams ovulated (95%) compared with ewes exposed to LP rams (78%) (P < .02). On the 1st d of exposure, the HP rams exhibited more courtship behavior and spent more time near the ewes (P < .04). The HP rams spent more time within 1 m of ewes during the 28-d exposure. There were no differences in the amount of contact with rams (LP or HP) between rise in progesterone indicate of ovulation tended to occur earlier (P = .06) in ewes penned with HP rams. A greater percentage of ewes exposed to LP rams (P = .03) had early elevations of progesterone with no concurrent sexual behavior. These data imply that in addition to a pheromone the sexual behavior of the ram may be important in initiating ovarian cycle activity.

Anestrus↗
PubMed1993

Hypothalamic and hypophyseal receptors for estradiol in high and low sexually performing rams.

Rams, characterized over a 3-year period as being high (n = 8) or low (n = 10) sexual performers, were euthanized to determine if differences in sexual behavior were associated with differences in hypophyseal and hypothalamic receptors for estradiol. Rams were exposed to estrous ewes and courtship behavior was recorded for 5 hr prior to tissue collection. Blood samples for determination of serum concentrations of luteinizing hormone (LH) were collected every 15 min during the behavior testing period. Hourly blood samples were analyzed for serum concentrations of estradiol (E) and testosterone (T). Rams characterized as high (HP) or low (LP) sexual performers had similar LH profiles; there were no differences noted in basal concentration, number of pulses, or pulse amplitude of LH. There were no differences in serum concentrations of T or E during the behavior testing period between HP and LP rams. Unoccupied receptors for E (moles E bound x 10(-15)) in the stalk-median eminence (SME) (P < 0.05) in HP rams (15.1 +/- 3.1) were greater than those in LP rams (4.6 +/- 1.9). Occupied receptors for E (moles E bound x 10(-15)) in the preoptic area (POA) (P < 0.1) in HP rams (6.0 +/- 0.8) tended to be greater than those in the LP rams (3.8 +/- 0.8). The proportion of total E receptors (occupied+unoccupied) in the POA that were occupied was greater (P < 0.05; 0.41 +/- 0.03 vs 0.23 +/- 0.04) for HP than for LP rams. In contrast, HP rams had less (P < 0.05) occupied E receptors (moles E bound x 10(-15)) in the anterior pituitary gland (AP) than LP rams (152.0 +/- 38.5 vs 337.3 +/- 51.7). The proportion (%) of E receptors that were occupied in the AP in HP rams also tended to be less (P < 0.06) than that in LP rams (8 +/- 2 vs 14 +/- 1). No differences were detected in occupied or unoccupied E receptors in the medial basal hypothalamus, medial amygdala, or stalk-median eminence. In conclusion, differences in occupied receptors for E in the POA and the AP, and unoccupied receptors for E in the SME, were associated with differences in ram sexual behavior.

Amygdala↗
PubMed1993

Feeding behavior of grazing ruminants experiencing stress.

The mechanisms underlying diet selection of ruminants are less studied than those for monogastrics. However, recent studies have shown that these mechanisms may be more similar in ruminants and monogastrics than previously believed. Food aversion learning is observed in both monogastrics and ruminants, and the hypothalamic-pituitary-adrenal axis appears to be involved in avoidance learning. Using leafy spurge (Euphorbia esula), an introduced weed whose expansion has costly ecological and economic implications in western North America, as a model for underconsumed plant species, we hypothesized that sheep experience increased cortisol levels when they first consume leafy spurge and that this may be related to their reluctance to graze it. We also hypothesized that preexposure to leafy spurge would attenuate the development of a spurge-based aversion. Correspondingly, we hypothesized that preexposed sheep would not experience increased blood cortisol levels with leafy spurge gavage during an aversion trial. None of our hypotheses were disproved by the experiments. Our results lend support to the hypothesis that stress is required for the development of conditioned taste aversions and extend it to ruminants. We suggest that activity of the hypothalamic-pituitary-adrenal axis is integral to food aversion learning in ruminants.

Animals↗
PubMed1993

The effects of different methods of estimating fecal output on plasma cortisol, fecal output, forage intake, and weight change in free-ranging and confined wethers.

Thirty-four white-face wethers (avg BW 56 kg) were used in two experiments to investigate differences in plasma cortisol, forage intake, fecal output, and BW change associated with two methods of estimating fecal output. The methods were fecal collection bags (B) and marker estimates of fecal output (U). A control treatment (C) was included in each experiment in which wethers were not bagged or dosed with the marker. Experiment 1 was conducted with wethers grazing dormant sagebrush-bunchgrass range. Experiment 2 was conducted with wethers housed in metabolism crates. In Exp. 1, the following differences were detected: 1) basal and mean integrated (following ACTH challenge) plasma cortisol levels were higher (P < .05) for U wethers than for C wethers, 2) no differences (P > .05) between B and C wethers were detected for basal or mean integrated plasma cortisol, 3) both B and U wethers gained (P < .05) weight, whereas C wethers lost weight, and 4) no differences (P > .05) between B and U wethers were detected for cortisol measurements, weight change, or fecal output. No differences (P > .05) were noted for any of the variables tested in Exp. 2. When treatments were combined within experiment to test Exp. 1 vs 2, time to peak cortisol levels was longer (P < .05) and mean integrated cortisol levels and weight change were lower (P < .05) for wethers in confinement than for wethers on range. No difference (P > .05) was detected for basal cortisol levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

External fixation of unstable metacarpal and phalangeal fractures.

A prospective study of the management of 30 patients with 37 unstable or complex metacarpal or phalangeal fractures treated with the "Shearer" micro-external fixator was carried out over an 18-month period. The stability achieved, with minimal soft-tissue tethering, allowed early joint mobilisation with good or excellent function in 94% of metacarpal and 85% of phalangeal fractures by nine weeks. There were no cases of non-union and few complications.

Equipment Design↗
PubMed1992

Luteinizing hormone, testosterone, and behavioral response of male-oriented rams to estrous ewes and rams.

During the breeding season three experiments were conducted to evaluate the LH and testosterone (T) response of rams with male sexual orientation (e.g., male-oriented homosexual rams) to female sheep, to male sheep, and to treatment with LHRH. Male-oriented rams were identified through a series of sexual performance and sexual preference tests. Treatments included exposure to estrous females and to males for 15 min (Exp. 1) and exposure to estrous females and to males for 8 h (Exp. 2). Behavioral responses to stimulus animals were recorded. In Exp. 2 homosexual rams mounted males more than females (P less than .02) and exhibited more flehmen (P less than .002) and investigatory sniffs (P less than .01) when exposed to males vs females. Acts of aggression (butting the stimulus animals) did not differ by gender (P greater than .1). Flehmen and butting were positively correlated to LH secretion (P less than .02) of rams exposed to females but not to males. In Exp. 1, LH concentration determined every 15 min for 6 h was not affected (P greater than .05) by the gender of the stimulus animal. In Exp. 2, LH pulse frequency and concentration were similar (P greater than .05) by treatment. Lack of an LH response to sexual activity in homosexual rams was not a result of pituitary or gonadal insensitivity; within 1 h of a single injection of LHRH both LH and T increased (Exp. 3).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Luteinizing hormone and testosterone response of sexually active and inactive rams.

The objective of this study was to identify rams exhibiting high (HP) and low (LP) levels of sexual performance and to determine whether their respective behavioral responses to ewes in estrus were related to changes in serum testosterone (T) and LH concentrations. Rams were selected on the basis of standardized serving capacity tests. Plasma T and LH concentrations in rams were measured in three experiments: 1) after 15 min of exposure to estrous ewes, 2) after an injection of 500 ng of LHRH, and 3) during an 11-h exposure to estrous ewes. During 15 min of exposure to ewes, HP rams were sexually active, whereas LP rams showed no sexual interest. Secretion of LH was similar (P greater than .05) between ram groups. Sexual arousal, copulation, and ejaculation of HP males were not related (P greater than .05) to LH secretion. Exposure to estrous ewes for 11 h, however, stimulated LH pulse frequency and elevated basal LH and T concentrations in HP but not LP rams (P less than .001). Luteinizing hormone secretion was positively correlated to the frequency of mounts (r = .19; P less than .01) and ejaculation (r = .17; P less than .03). Aggressive behavior of rams directed at ewes was negatively correlated to LH (r = -.22 P less than .003). Concentrations of LH and T after LHRH injection were similar between HP and LP rams (P greater than .05). These results show that the effects of the ewe on LH secretion of rams depend on length of the exposure period and sexual activity of the male.

Aggression↗
PubMed1992

Sexual performance of rams in serving capacity tests predicts success in pen breeding.

The purpose of this study was to determine the extent to which sexual performance (serving capacity) tests can be used to predict the sexual behavior and reproductive success of rams in the context of pen mating. Standard serving capacity tests were used to select four low (LP) and four high-performing (HP) rams from a population of 94 yearling males. Each selected ram was then exposed to approximately 30 estrus-synchronized ewes for a 9-d period. Ejaculations observed and mounting marks left on ewes confirmed the greater (P less than .001) sexual activity of the HP rams in the field. In addition, ewes exposed to HP rams had a higher lambing percentage, more lambs born, and more live lambs born per ewe. Ram classification was not related (P greater than .60) to the number of lambs born per ewe lambing (prolificacy). It was concluded that serving capacity tests, properly conducted, can be used to predict ram mating performance and thus aid in establishing more efficient ram-to-ewe stocking rates.

Animals↗
PubMed1992

The effects of fat interposition for central-physeal defects. A histologic study in rabbits.

The effects of autogeneic fat interposition in a central cylindrical physeal defect were observed in rabbits. A 3.6-mm longitudinal drill hole was made across the physis of the distal femur, bilaterally, in four- to six-week-old New Zealand rabbits. One side was filled with an autogeneic fat graft and the contralateral defect was left as a control. The rabbits were killed at intervals during the remaining growth period, and the defects were examined histologically. Although fat grafts reduced the rate of osseous bridging across the physis and allowed more longitudinal growth than controls, transverse regeneration of the physis did not occur in the eight-week period preceding closure. The lack of physeal regeneration across the gap may reflect an important difference between central and peripheral defects.

Adipose Tissue↗
PubMed1991

Effects of melatonin on seasonal changes in reproduction of rams.

Three studies were conducted to determine the effects of exogenous melatonin (M) on changes in scrotal circumference (SC), fertility and reproductive hormone concentrations of rams. Rams were initially housed in barns with controlled photoperiod and given 16 wk of long (16L:8D) or short (8L:16D) days. In Studies I and II, implants of M were given for 40 to 80 d beginning at maximal SC. Results showed that implanted rams had greater (P less than .05) blood M concentrations than nonimplanted controls. However, M did not prevent testicular regression. In Study III, M was given to rams after testicular regression had occurred. Rams were implanted with M weekly for 6 or 4 wk, followed by a withdrawal period of 4 wk (6:4, 4:4 respectively). Results showed that M (6:4) stimulated (P less than .05) testicular growth compared with nonimplanted controls. Treatment of rams with M for 8 mo did not affect LHRH-induced LH release (P greater than .05), but it reduced basal and LHRH-induced testosterone release (P less than .05). Reproductive performance of rams in Studies I and III was compared with that of nonimplanted rams. Fertility of M-treated rams in the spring from Studies I and III (86% to 91%) was similar to that in autumn (93%). Fertility of rams from Studies I and III exceeded (P less than .05) that of nonimplanted rams in April (59% to 62%). Net lamb production from ewes mated in the spring was greater if rams were treated with M and(or) photoperiod.

Animals↗
PubMed1988

Influence of concentration, duration and route of administration of melatonin on reproductive performance of spring-mated polypay and polypay-cross ewes.

The effects of exogenous melatonin on reproductive performance of 737 Polypay and Polypay-cross ewes were evaluated during a late March and April breeding period. Different concentrations (2 or 10 mg) routes of administration (fed vs implanted) and durations of administration (20 or 40 d before breeding) were studied. Estrus was synchronized in all ewes using 60 mg medroxyprogesterone acetate (MAP) in a vaginal pessary. Number of mature ewes lambing/ewe present at lambing was increased (P less than .05) nearly 20% by implanting for 40 d with melatonin (75%) or by feeding either 2 (72%) or 10 mg (73%) melatonin for 40 d before spring breeding compared with untreated control ewes (54%) or ewes implanted for only 20 d before breeding (58%). Date of lambing, number of lambs born/ewes lambing and number of lambs born alive/ewe lambing were not altered significantly by treatments. Number of yearling ewes (n = 166 for ewes 1.5 yr old at lambing time) lambing/ewe present at lambing was lower (P less than .01; 26%) than that of mature ewes (n = 381, greater than or equal to 2.0 yr; 68%). We concluded that feeding 2 or 10 mg melatonin or implanting melatonin for 40 d enhanced reproductive performance and effectively overcame the restrictions of seasonality of breeding in mature ewes. In yearling ewes, 10 mg melatonin increased the number of ewes lambing.

Administration, Oral↗
PubMed1987

Cerclage wiring in the management of comminuted fractures of the femoral shaft.

A retrospective series of 20 patients is presented, comprising 21 fractures of the femoral shaft treated by open reduction and internal fixation (usually by medullary nailing) combined with cerclage wiring. Most of the patients were young with comminuted fractures of the femoral shaft, many with multiple injuries. The aims of stable reduction and early sound union of the fracture in anatomical position were achieved in all cases and that of early mobilization of the knee to a good ultimate range of flexion in almost all cases.

Accidental Falls↗