PubMed Health⌕ Search

Biomedical subjects

L R Gentry

Publications and source records attributed to L R Gentry.

At least 19 recordsLinked to original sources
PubMed2004

Flow paths of plant tissue residues and digesta through gastrointestinal segments in Spanish goats and methodological considerations.

A sequence of eight twice-daily meals, each marked with different rare earth elements, was fed to 24 Spanish goats (BW = 20.6 +/- 1.94 kg) to produce meal-based profiles of rare earth markers within segments of the gastrointestinal digesta on subsequent slaughter. Accumulative mean residence time and time delay of rare earths and segmental and accumulative mean residence times of indigestible NDF (IDF) were estimated for each sampled segment. Diets consisted of ad libitum access to bermudagrass hay with a limit feeding of one of four supplements: 1) minerals (basal, B); 2) B + energy (E); 3) B + CP (CP); or 4) B + E + CP for 84 d. Mean daily intake (g/kg of BW) during the 5 d before slaughter differed (P < 0.05) via diet for DM but not for IDF (8.0 +/- 0.35 g/kg of BW). Larger estimates of cumulative mean residence time for IDF vs. rare earths were suggested to be the consequence of a meal-induced bias in the single measurement of IDF pool size by anatomical site. The rare earth compartment method was considered more reliable than the IDF pool dilution method because it yielded flow estimates based on the flux of eight meal-dosed rare earth markers over 4 d and was independent of anatomical definitions of pool size. Statistically indistinguishable estimates for gastrointestinal mean residence times for IDF and rare earths conform to assumed indelibility for the specifically applied rare earths and indigestibility of IDF. The potentially digestible NDF (PDF):IDF ratio of dietary fragments (0.8) progressively decreased in the following order: caudodorsal reticulorumen (0.390) > crainodorsal reticulorumen (0.357) approximately reticulum (0.354) > mid-dorsal reticulorumen (0.291) approximately ventral reticulorumen (0.286), to that within the omasal folds and in the abomasum (0.259). Such a gradient of progressively aging mixture of plant tissue fragments is consistent with age-dependent flow paths established in the reticulorumen and flowing to the omasum and abomasum. Such heterogeneity of fragment ages within the reticulorumen is also indicated by the superior fit of marker dose site double dagger marker sampling site model assumptions. Additionally, cyclic meal- and rumination-induced variations in escape rate occur. Estimates of mean escape rates over days, needed for the practice of ruminant nutrition, must consider the complex interactions among plant tissues and the dynamics of their ruminal digestion of PDF.

Abomasum↗
PubMed2003

Concentrations of nitric oxide in equine preovulatory follicles before and after administration of human chorionic gonadotropin.

In the present study, follicular fluids of estrous mares treated with saline solution (Control) or nitric oxide synthase (NOS) inhibitors were analyzed for nitric oxide (NO), estradiol-17beta (E2) and progesterone (P4) concentrations before and 36h after administration of human chorionic gonadotropin (hCG). Follicular fluids obtained before (0h) hCG administration from control mares had lower concentrations of NO than those obtained 36h after administration of hCG (58.3+/-17.8 micromol versus 340.4+/-57.7 micromol; P<0.05). A similar pattern was also noted for intrafollicular P4 in control mares, which had lower concentrations of intrafollicular P4 before hCG than 36h post-hCG administration (P<0.05). As expected, E2 concentrations of control follicles sampled before hCG administration were higher than those sampled 36h post-hCG administration (P<0.05). However, the E2 concentrations in follicles of mares treated with the NOS inhibitors N(omega)-nitro-L-arginine methyl ester (L-NAME) or aminoguanidine (AG) did not decrease after hCG administration, unlike those in control mares (P>0.10). In addition, mares treated with NOS inhibitors had lower intrafollicular concentrations of NO and P4 than control mares, both before and after hCG administration (P<0.05). Increased intrafollicular concentrations of NO in control, hCG-stimulated mares provide evidence for the presence of an NO-generating system in the equine preovulatory follicle that is likely upregulated following administration of hCG.

Animals↗
PubMed2003

Effects of dexamethasone, glucose infusion, adrenocorticotropin, and propylthiouracil on plasma leptin concentrations in horses.

In experiment 1, nine light horse geldings (three 3 x 3 Latin squares) received dexamethasone (DEX; 125 microg/kg BW, i.m.), glucose (0.2 g/kg BW, i.v.), or nothing (control) once per day for 4 days. DEX increased (P < 0.001) glucose, insulin, and leptin concentrations and resulted in a delayed increase (P < 0.001) in IGF-I concentrations. In experiment 2, mares were similarly treated with DEX (n = 6) or vehicle (n = 6). DEX again increased (P < 0.01) glucose, insulin, and leptin concentrations; the delayed elevation in IGF-I concentrations occurred on day 10, 12, and 19, relative to the first day of treatment. In experiment 3, six light horse geldings received either 200 IU of adrenocorticotropin (ACTH) i.m. or vehicle twice daily for 4 days. ACTH increased (P < 0.001) cortisol concentrations. Further, ACTH resulted in increases (P < 0.01) glucose, insulin, and leptin concentrations. In experiment 4, plasma samples from four light horse stallions that were fed 6-n-propyl-2-thiouracil (PTU) at 6 mg/kg BW for 60 days to induce hypothyroidism were compared to samples from control stallions. On day 52, stallions receiving PTU had lower concentrations of thyroxine (P < 0.05) and triiodothyronine (P < 0.01) and higher (P < 0.01) concentrations of TSH. Leptin concentrations were higher (P < 0.01) in PTU-fed stallions from day 10 through 52. In conclusion, circulating concentrations of leptin in horses was increased by administering DEX. Treatment with ACTH increased cortisol and resulted in lesser increases in leptin, glucose, and insulin. In addition, PTU feeding results in lesser increases in leptin concentrations.

Adrenocorticotropic Hormone↗
PubMed2003

Endocrine responses in mares and geldings with high body condition scores grouped by high vs. low resting leptin concentrations.

Previous observations from this laboratory indicated that horses with high BCS could have resting plasma leptin concentrations ranging from low (1 to 5 ng/mL) to very high (10 to 50 ng/mL). To study the possible interactions of leptin secretion with other endocrine systems, BCS and plasma leptin concentrations were measured on 36 mares and 18 geldings. From mares and geldings that had a mean BCS of at least 7.5, five with the lowest (low leptin) and five with the highest (high leptin) leptin concentrations were selected. Jugular blood samples were collected twice daily for 3 d from the 20 selected horses to determine average resting hormone concentrations. Over the next 12 d, glucose infusion, injection of thyrotropin-releasing hormone (TRH), exercise, and dexamethasone treatment were used to perturb various hormonal systems. By design, horses selected for high leptin had greater (P < 0.0001) leptin concentrations than horses selected for low leptin (14.1 vs. 2.8 +/- 0.92 ng/mL, respectively). In addition, mares had greater (P = 0.008) leptin concentrations than geldings. Horses selected for high leptin had lower (P = 0.027) concentrations of GH but higher (P = 0.0005) concentrations of insulin and thriiodothyronine (T3) than those selected for low leptin. Mares had greater (P = 0.0006) concentrations of cortisol than geldings. There was no difference (P > 0.10) in concentrations of IGF-1, prolactin, or thyroid-stimulating hormone (TSH). Horses selected for high leptin had a greater (P = 0.0365) insulin response to i.v. glucose infusion than horses selected for low leptin. Mares had a greater (P = 0.0006) TSH response and tended (P = 0.088) to have a greater prolactin response to TRH than geldings; the T3 response was greater (P = 0.047) in horses selected for high leptin. The leptin (P = 0.0057), insulin (P < 0.0001), and glucose (P = 0.0063) responses to dexamethasone were greater in horses selected for high leptin than in those selected for low leptin. In addition, mares had a greater (P < 0.0001) glucose response to dexamethasone than geldings. Cortisol concentrations were decreased (P = 0.029) by dexamethasone equally in all groups. In conclusion, differences in insulin, T3, and GH associated with high vs. low leptin concentrations indicate a likely interaction of these systems with leptin secretion in horses and serve as a starting point for future study of the cause-and-effect nature of the interactions.

Animals↗
PubMed2003

Thyrotropin releasing hormone interactions with growth hormone secretion in horses.

Light horse mares, stallions, and geldings were used to 1) extend our observations on the thyrotropin releasing hormone (TRH) inhibition of GH secretion in response to physiologic stimuli and 2) test the hypothesis that stimulation of endogenous TRH would decrease the normal rate of GH secretion. In Exp. 1 and 2, pretreatment of mares with TRH (10 microg/kg BW) decreased (P < 0.001) the GH response to exercise and aspartate infusion. Time analysis in Exp. 3 indicated that the TRH inhibition lasted at least 60 min but was absent by 120 min. Administration of a single injection of TRH to stallions in Exp. 4 increased (P < 0.001) prolactin concentrations as expected but had no effect (P > 0.10) on GH concentrations. Similarly, 11 hourly injections of TRH administered to geldings in Exp. 5 did not alter (P > 0.10) GH concentrations either during the injections or for the next 14 h. In Exp. 5, it was noted that the prolactin and thyroid-stimulating hormone responses to TRH were great (P < 0.001) for the first injection, but subsequent injections had little to no stimulatory effect. Thus, Exp. 6 was designed to determine whether the inhibitory effect of TRH also waned after multiple injections. Geldings pretreated with five hourly injections of TRH had an exercise-induced GH response identical to that of control geldings, indicating that the inhibitory effect was absent after five TRH injections. Retrospective analysis of pooled, selected data from Exp. 4, 5, and 6 indicated that endogenous GH concentrations were in fact lower (P < 0.01) from 45 to 75 min after TRH injection but not thereafter. In Exp. 7, 6-n-propyl-2-thiouracil was fed to stallions to reduce thyroid activity and hence thyroid hormone feedback, potentially increasing endogenous TRH secretion. Treated stallions had decreased (P < 0.01) concentrations of thyroxine and elevated (P < 0.01) concentrations of thyroid-stimulating hormone by d 52 of feeding, but plasma concentrations of GH and prolactin were unaffected (P > 0.10). In contrast, the GH response to aspartate and the prolactin response to sulpiride were greater (P < 0.05) in treated stallions than in controls. In summary, TRH inhibited exercise- and aspartate-induced GH secretion. The duration of the inhibition was at least 1 h but less than 2 h, and it waned with multiple injections. There is likely a TRH inhibition of endogenous GH episodes as well. Reduced thyroid feedback on the hypothalamic-pituitary axis did not alter basal GH and prolactin secretion.

Animals↗
PubMed2002

The relationship between body condition, leptin, and reproductive and hormonal characteristics of mares during the seasonal anovulatory period.

An experiment was conducted to determine the effects of high vs low body condition scores (BCS) produced by restricted feeding on reproductive characteristics, hormonal secretion, and leptin concentrations in mares during the autumnal transition and winter anovulatory period. Mares with BCS of 6.5 to 8.0 were maintained on pasture and/or grass hay, and starting in September, were full fed or restricted to produce BCS of 7.5 to 8.5 (high) or 3.0 to 3.5 (low) by December. All but one mare with high BCS continued to ovulate or have follicular activity during the winter, whereas mares with low BCS went reproductively quiescent. Plasma leptin concentrations varied widely before the onset of restriction, even though all mares were in good body condition. During the experiment, leptin concentrations gradually decreased (P < 0.0001) over time in both groups, but were higher (P < 0.009) in mares with high vs low BCS after 6 wk of restriction, regardless of initial concentration. No differences (P > 0.1) between groups were detected for plasma concentrations of LH, FSH, TSH, GH, glucose, or insulin in samples collected weekly; in contrast, plasma prolactin concentrations were higher (P < 0.02) in mares with high BCS, but also decreased over time (P < 0.008). Plasma IGF-I concentrations tended (P = 0.1) to be greater in mares with high vs low BCS. The prolactin response to sulpiride injection on January 7 did not differ (P > 0.1) between groups. During 12 h of frequent blood sampling on January 12, LH concentrations were higher (P < 0.0001), whereas GH concentrations (P < 0.0001) and response to secretagogue (EP51389; P < 0.03) were lower in mares with high BCS. On January 19, the LH response to GnRH was higher (P < 0.02) in mares with high BCS; the prolactin response to TRH also was higher (P < 0.01) in mares with high BCS. In conclusion, nutrient restriction resulting in low BCS in mares resulted in a profound seasonal anovulatory period that was accompanied by lower leptin, IGF-I, and prolactin concentrations. All but one mare with high BCS continued to cycle throughout the winter or had significant follicular activity on the ovaries. Although leptin concentrations on average are very low in mares with low BCS and higher in well-fed mares, there is a wide variation in concentrations among well-fed mares, indicating that some other factor(s) may determine leptin concentrations under conditions of high BCS.

Animals↗
PubMed2002

Responses of seasonally anovulatory mares to daily administration of thyrotropin-releasing hormone and(or) gonadotropin-releasing hormone analog.

Seventeen seasonally anovulatory light horse mares were treated daily, starting January 5 (d 1), for 28 d with GnRH analog (GnRH-A; 50 ng/kg BW) and(or) thyrotropin-releasing hormone (TRH; 5 microg/kg BW) in a 2 x 2 factorial arrangement of treatments to test the hypothesis that combined treatment may stimulate follicular growth and development. Ovaries were examined via ultrasonography and jugular blood samples were collected every 3 d. Frequent blood samples were collected after treatment injections on d 1, 2, 4, 7, 11, 16, and 22; on d 29, all mares received an i.v. mixture of GnRH, TRH, sulpiride, and EP51389 (a growth hormone secretagogue) to assess pituitary responsiveness. No consistent effects (P > 0.1) of treatment were observed for plasma LH, FSH, prolactin, or thyroxine concentrations in samples collected every 3 d. The only effect on ovarian follicle numbers was a reduction in number of follicles 11 to 19 mm in diameter due to TRH treatment (P = 0.029). No mare ovulated during treatment. On the days of frequent sampling, mean LH (P = 0.0001) and FSH (P = 0.001) concentrations were higher in mares receiving GnRH-A and tended to increase from d 1 through 7. In contrast, mean prolactin (P = 0.001) and thyroid-stimulating hormone (P = 0.0001) concentrations were high in mares receiving TRH on d 1 but rapidly decreased thereafter. When mares were administered the secretagogue mixture on d 29, the LH response was greater (P = 0.0002) in mares that had previously received GnRH-A but the FSH response was not affected (P > 0.1); the prolactin response was greater (P = 0.014) and the TSH response was smaller (P = 0.0005) in mares that had previously received TRH. Surprisingly, an immediate growth hormone response to EP51389 was absent in all mares. In conclusion, daily GnRH-A treatment stimulated plasma LH and FSH concentrations immediately after injection; although no long-term elevation in preinjection concentrations was achieved, the responses gradually increased over time, indicating a stimulation of gonadotropin production and storage. Daily treatment with TRH stimulated plasma TSH and prolactin concentrations, but the response diminished rapidly and was minimal within a few days, indicating a depletion of pituitary stores and little or no stimulation of production. There was no beneficial effect of adding TRH treatment to the daily GnRH-A regimen.

Anestrus↗
PubMed2002

High versus low body condition in mares: interactions with responses to somatotropin, GnRH analog, and dexamethasone.

Mares that had previously been fed to attain body condition scores (BCS) of 7.5 to 8.5 (high) or 3.0 to 3.5 (low) were used to determine the interaction of BCS with the responses to 1) administration of equine somatotropin (eST) daily for 14 d beginning January 20 followed by administration of GnRH analog (GnRHa) daily for 21 d and 2) 4-d treatment with dexamethasone later in the spring when mares in low BCS had begun to ovulate. The majority of mares with high BCS continued to cycle throughout the winter, as evidenced by larger ovaries (P < 0.002), more corpora lutea (P < 0.05), greater progesterone concentrations during eST treatment (P < 0.04), and more (P < 0.05) large- and medium-sized follicles. Treatment with eST alone or in combination with GnRHa had no effect (P > 0.05) on ovarian activity or ovulation. Plasma leptin concentrations were greater (P < 0.002) in mares with high BCS; however, there was no effect (P > 0.10) of eST treatment. Plasma IGF-I concentrations were greater (P < 0.0001) in mares treated with eST compared with mares given vehicle, and mares with high BCS had greater IGF-I (P < 0.02) and LH concentrations (P < 0.02) than mares with low BCS. Plasma leptin concentrations in mares with high BCS were increased (P < 0.001) within 12 h of dexamethasone treatment; the leptin response (P < 0.001) in mares with low BCS was greatly reduced (P < 0.001) and transient. Glucose and insulin concentrations also increased (P < 0.0001) after dexamethasone treatment in both groups, and the magnitude of the response was greater (P < 0.0001) in mares with high BCS than in mares with low BCS. In summary,low BCS in mares was associated with a consistent seasonal anovulatory state that was affected little by eST and GnRHa administration. In contrast, all but one mare with high BCS continued to experience estrous cycles and(or) have abundant follicular activity on their ovaries. The IGF-I response to eST treatment was also reduced in mares with low BCS, as was the basal leptin concentration and leptin response to dexamethasone. Although low BCS and leptin concentrations were associated with inactive ovaries during winter and early spring, mares with low BCS eventually ovulated in April and May while leptin concentrations remained low.

Animals↗
PubMed2001

Pituitary hormone and insulin responses to infusion of amino acids and N-methyl-D,L-aspartate in horses.

Thirty-nine adult light horse mares, geldings, and stallions were used in two experiments to assess the pituitary hormone and insulin responses to infusions of arginine, aspartic acid, lysine, glutamic acid, and N-methyl-D,L-aspartate (NMA). In Exp. 1, 27 horses were assigned to one of three infusion treatments: 1) physiological saline (1 L); 2) 2.855 mmol of arginine/kg BW in 1 L of water; or 3) 2.855 mmol of aspartic acid/kg BW in 1 L of water. In Exp. 2, 12 horses were assigned, in a multiple-square 4 x 4 Latin square design, to one of four infusion treatments: 1) 2 mL of saline/kg BW; 2) 2.855 mmol of lysine/kg BW in water; 3) 2.855 mmol of glutamic acid/kg BW in water; or 4) 1 mg of NMA/kg BW in water. In Exp. 1, an acute (within 20 min) release of growth hormone (GH) was induced (P = 0.002) by aspartic acid. In contrast, acute release of prolactin (P = 0.001) and insulin (P = 0.002) was induced only by arginine; moreover, the arginine effect on insulin was present only in mares (P = 0.011). In Exp. 2, an acute release of GH was induced (P = 0.001) by glutamic acid and NMA. In males, the glutamic acid-induced GH release was greater than that of NMA; in mares, the NMA-induced GH release was greater than that of glutamic acid (P = 0.069). Both lysine and glutamic acid induced (P = 0.001) acute release of prolactin, whereas an acute release of insulin was elicited (P = 0.002) only by lysine. The NMA-induced LH response was due almost entirely to the response in mares and stallions (P = 0.016), and the NMA-induced FSH release was due almost entirely to the response in mares (reproductive status effect; P = 0.004). In the horse, aspartic acid, glutamic acid, and NMA seem to stimulate GH release; arginine and lysine seem to stimulate prolactin and insulin release; and NMA seems to stimulate LH and FSH release. It seems that N-methyl-D-aspartate glutamate receptors are involved in controlling GH, LH, and FSH secretion, whereas other mechanisms are involved with prolactin secretion. These results also indicate that gonadal steroids interact with amino acid-induced pituitary hormone release in adult horses.

Amino Acids↗
PubMed2000

Magnetic resonance imaging of the arc of contact of extraocular muscles: implications regarding the incidence of slipped muscles.

BACKGROUND: Slipped muscles are complications of strabismus surgery that are encountered more frequently after recessions of the inferior and medial rectus muscles. METHODS: We obtained multipositional high-resolution magnetic resonance imaging of 10 orbits of 6 normal subjects, 9 orbits of 5 patients with thyroid-associated eye disease, and 4 orbits of 2 patients with thyroid-associated eye disease on the day after rectus muscle recessions using a suspension technique. The arc of contact and the distance between the insertion and the point of tangency of each of the extraocular muscles to the globe were measured in primary position as well as in the cardinal fields. RESULTS: The data confirm that the inferior and medial rectus muscles have a significantly smaller wraparound effect on the globe than the superior and lateral rectus muscles, respectively (P =.022 for the vertical rectus muscles; P =.05 for the horizontal rectus muscles, paired t test), and that their insertions may be found several millimeters posterior to their points of tangency in extreme rotation of the globe in their respective field of action. The appearance of the suspended recessed inferior rectus muscle on the first postoperative day and its decreased apposition to the globe raise concerns about the muscle losing contact with the globe in extreme downgaze. CONCLUSIONS: The small wraparound effect of the inferior and medial rectus muscles may explain one of the mechanisms accounting for the increased incidence of slipped muscles encountered after recessions of these muscles.

Data Interpretation, Statistical↗
PubMed1999

Magnetic resonance imaging procedures to study the concurrent anatomic development of vocal tract structures: preliminary results.

The vocal tract structures undergo drastic anatomic restructuring during the course of development from infancy to adulthood. This study demonstrates the feasibility of using MRI to examine the growth processes of the vocal tract. This method affords precise and detailed visualization of the soft tissues in the oro-pharyngeal region, while also providing images of related bony and cartilaginous structures. Information on anatomic restructuring contributes to the understanding of how speech emerges and develops, and it also establishes normative information that can be used in the assessment of developmental anomalies. This paper describes the method used to measure and examine the concurrent anatomic development of the various vocal tract structures during early childhood. Preliminary results from two pediatric subjects indicate that there is synchrony of growth in the different structures-both soft and hard tissues-, and that such synchronous growth appears to persist during periods of growth spurts.

Child, Preschool↗
PubMed1999

Proteus syndrome: craniofacial and cerebral MRI.

The Proteus syndrome is a rare hamartoneoplastic syndrome that may affect the brain, skull, and extracranial head and neck. We present a case with severe, characteristic findings. Brain abnormalities are not common in Proteus syndrome; when present, hemimegalencephaly and migrational disorders are typically seen, commonly with an associated seizure disorder. Maxillary and mandibular dysmorphism may occur, including unilateral condylar hyperplasia. Subcutaneous fatty, fibrous, lymphangiomatous masses commonly seen in this syndrome may involve the neck and face, leading to disfigurement and potential airway compromise.

Brain↗
PubMed1999

Dietary protein and chromium tripicolinate in Suffolk wether lambs: effects on production characteristics, metabolic and hormonal responses, and immune status.

Thirty-two Suffolk wether lambs were fed for 84 d in a 2 x 2 factorial experiment using two levels of dietary protein (9.0 to 12.1% CP, low protein, LP; or 12.8 to 14.4% CP, high protein, HP) and supplemental Cr (none, C; or 400 ppb Cr as chromium tripicolinate, Cr). At 14- to 21-d intervals, lambs were weighed, and jugular blood samples were collected. Mean ADG and carcass weight (P > .10) did not differ. In lambs fed HP, Cr reduced liver weight and increased kidney weight (P < .01). Lambs fed HP had elevated plasma urea N (PUN; P < .01) and albumin (P < .04). During an i.v. epinephrine challenge on d 43, plasma cortisol declined in lambs fed Cr (Cr x time, P < .03) and in lambs fed LP (CP x time, P < .001). An i.v. glucose tolerance test conducted 3 h later showed that supplemental Cr decreased glucose clearance rate in lambs fed HP (CP x Cr, P < .10) but not in lambs fed LP. On d 62, PUN was increased in lambs fed HP (P < .001) between 0 and 3 h postprandial, and there was a Cr x CP interaction (P < .04). Postprandial plasma NEFA declined with Cr vs C (Cr x time, P < .07) and with HP vs LP (CP x time, P < .10). By d 66, lambs fed Cr had an elevated (P < .03) blood platelet and fibrinogen content. Chromium increased erythrocyte count in lambs fed HP (Cr x CP, P < .08), and isolated peripheral lymphocytes had greater blastogenic response to 4 microg/mL of phytohemagglutinin (Cr x CP, P < .001). The lymphocyte response to pokeweed mitogen (.2 microg/mL) was reduced in lambs fed Cr (P < .10). In the present experiment, Cr supplementation had minimal and inconsistent effects on production and metabolic criteria of lambs.

Animals↗
PubMed1998

Systemic diseases involving the orbit.

A variety of systemic pathological processes may involve the eye and the surrounding orbital adnexae. CT and MRI of the orbit have become useful clinical adjuvants, not only in establishment of the diagnosis, but also in suggesting the appropriate clinical treatment, sometimes preventing needless biopsy. Grave's disease, Wegener's granulomatosis, and sarcoidosis may all present initially with orbital disease before the onset of systemic manifestations. Idiopathic inflammatory disease of the orbit and lymphoproliferative disease of the orbit continue to remain radiological and clinical challenges. The article discusses the CT and MRI appearance of many of the common systemic diseases in adults with attention to features useful in clinical practice as well as in differential diagnosis.

Adult↗
PubMed1998

Influence of intravenous L-carnitine administration in sheep preceding an oral urea drench.

Two experiments were conducted to investigate the effect of i.v. administration of L-carnitine on selected metabolites in sheep and to determine the feasibility of using L-carnitine to ameliorate the deleterious effects of hyperammonemia in sheep. In Exp. 1, i.v. L-carnitine solutions were administered at three levels in a replicated Latin square: 0 (CONT), 6.36 (CAR 1), and 12.72 (CAR 2) mmol L-carnitine/kg x (75) BW using Suffolk ewes (n = 6; average BW 75+/-3 kg). Plasma L-carnitine concentration was increased (P<.05) by treatment (51.9 vs 102.3, and 96.4 micromol/L in CONT, CAR 1, and CAR 2, respectively). Plasma glucose concentration was elevated (P<.05) in CAR 2 and CAR 1. Plasma NEFA concentration was highest (P<.05) in CAR 2. Area under the response curve for glucose was greater (P<.02) in CAR 2. In Exp. 2, Suffolk ewes (n = 16; average BW 48+/-2 kg) were used in a randomized complete block design with a 2x2 factorial treatment arrangement to determine the effects of i.v. L-carnitine administration during an oral urea load test (OULT). L-Carnitine (0 and 6.36 mmol/kg x (75) BW) was administered i.v. at 30 min, and an oral urea drench (50% wt/vol; 0 and 300 mg/kg BW) was administered at 60 min. Plasma L-carnitine was increased (P<.0001) by i.v. L-carnitine. Plasma ammonia N was highest (P<.0001) in the UREA treatment compared with the CONT, CARN, and CARN + UREA treatments (148 vs 95, 101, and 108 micromol/L, respectively). Intravenous L-carnitine administration influenced plasma glucose and NEFA concentrations in sheep and, when administered 30 min preceding an OULT, prevented the development of subclinical hyperammonemia in sheep.

Administration, Oral↗
PubMed1998

Effects of fish meal and sodium bentonite on daily gain, wool growth, carcass characteristics, and ruminal and blood characteristics of lambs fed concentrate diets.

We evaluated the effects of replacing some soybean meal (SBM) protein with fish meal (FM) protein in diets adequate and slightly deficient in CP, with or without .75% sodium bentonite (NaB) on performance and ruminal and blood metabolites of individually fed Suffolk lambs. Diets were based on corn, SBM, and cottonseed hulls. In Exp. 1, five lambs were assigned to each of the three dietary treatments (11% CP with 3% FM, 13% CP with 0 or 3% FM). Lambs fed diets that contained 11% CP with 3% FM or 13% CP with 0% FM had similar DMI and ADG. Gain and feed efficiency were slightly improved (P = .18) by the 13% CP diet with 3% FM. In Exp. 2, 32 lambs were assigned to four dietary treatments (13.5% CP of DM) in a 2 x 2 factorial arrangement (0 or 3% FM, and 0 or .75% NaB on an as-fed basis). The DMI and ADG were increased (P < .05) by FM and NaB supplementation. Interactions (P < .05) revealed that NaB increased DMI, ADG, gain per feed (g/kg of DMI), and plasma urea N concentration in the absence of FM but not in the presence of FM in the diet. Neither FM nor NaB influenced (P = .25) wool growth. Total ruminal VFA were increased (P < .06) by FM and NaB. Differences in mineral content of phalanx bone, liver, and kidney were small and may be related to the mineral content of diets and the effect of NaB on mineral solubilities. Similar DMI and ADG of lambs fed FM and NaB separately and in combination suggest that their beneficial effect is not additive.

Animal Feed↗
PubMed1998

Anatomy of the orbit.

The normal orbit arguably contains the most complex anatomy of the human body. The orbit's small size, complex anatomy, and elaborate function make it a diagnostic challenge to evaluate. Magnetic resonance imaging (MRI) and computed tomography (CT) are essential studies for visualization of most normal and abnormal orbital structures. These studies also can help to understand some of the functional anatomical relationships within the orbit. This article attempts to review and illustrate the normal anatomical structures that can be identified on CT and MR images. These structures include the bony orbit, globe and optic nerve, extraocular muscles, lid retractor system, fibrous tissue framework, vascular system, neural structures, and lacrimal system.

Eye↗