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Biomedical subjects

D L Cross

Publications and source records attributed to D L Cross.

At least 19 recordsLinked to original sources
PubMed2003

Domperidone can ameliorate deleterious reproductive effects and reduced weight gain associated with fescue toxicosis in heifers.

The aim of this study was to evaluate the effect of a dopamine antagonist, domperidone, in nonpregnant, reproductively cycling heifers consuming endophyte-infected (EI) fescue diets. Thirty crossbred heifers (Angus x Holstein or Hereford x Holstein) were assigned to one of three treatment groups (n = 10); endophyte-free (EF) fescue diet, EI fescue diet, or endophyte-infected diet and treated with domperidone (EID). Heifers fed EI diets had decreased weight gains compared with heifers fed EF or EID (P < 0.05) during a 21-d treatment period. Ovarian structures were monitored via transrectal ultrasound to determine follicle size and day of ovulation. Blood plasma samples were collected daily and analyzed for progesterone concentration to determine luteal function. Heifers ingesting EI diets had estrous cycles of shorter duration and lower mid-cycle progesterone concentrations than heifers in the EF or EID treatments (P < 0.05). Ovaries from a subset of heifers in each group (n = 3 per group) were harvested and in vitro secretion of progesterone from luteal tissue extracts was determined. No differences in progesterone concentrations were detected among luteal tissue incubates (P > 0.05). These results suggest that domperidone supplementation of heifers consuming EI fescue may ameliorate certain symptoms of fescue toxicosis.

Acremonium↗
PubMed2000

Effect of rapid maxillary expansion on skeletal, dental, and nasal structures: a postero-anterior cephalometric study.

The purpose of this study was to compare the transverse dimensions of skeletal, dental, and nasal structures of a group of patients with maxillary narrowness before and after rapid maxillary expansion (RME) with an untreated control group using postero-anterior (PA) cephalometric radiographs. The material consisted of PA cephalograms of 25 children with a posterior crossbite (mean age 13 years 4 months), and 25 age- and sex-matched controls (mean age 13 years 11 months). Both groups consisted of 20 females and five males. Thirty-four reference points were digitized using the Dentofacial Planner software program. The 17 variables studied consisted of six skeletal, four dental, and seven intra-nasal linear measurements. Student's t-tests were used to compare the differences between the groups, and the effect of RME on skeletal, dental, and nasal structures. RME produced small, but statistically significant changes in maxillary width, upper and lower molar widths, the width between upper central incisor apices, and intra-nasal width. When compared with previous studies, the changes observed were similar for patients of a similar age group, but less than reported for a younger population. There is some evidence that the pattern of expansion produced by RME will vary depending on the age and maturity of the subject.

Adolescent↗
PubMed1997

Airway obstruction in ulcerative colitis.

We present a case of fulminant ulcerative colitis with associated extraintestinal manifestations, including upper airway obstruction from acute laryngotracheitis. Review of the literature shows few other cases of airway obstruction in chronic inflammatory bowel disease. Aggressive medical management of the underlying inflammatory bowel disease may facilitate a conservative approach to airway management, as in this case.

Adult↗
PubMed1995

Comparison of periodontal disease in HIV seropositive subjects and controls (I). Clinical features.

The aims of this study were to investigate the prevalence and severity of periodontal diseases in HIV seropositive and assumed HIV seronegative individuals in the Edinburgh area. 29 HIV seropositive subjects were examined at baseline and at 3-monthly intervals. Attachment loss and dichotomous indicators of periodontal disease were recorded. 27 control subjects were seen at baseline only. Although there was no significant difference between the 2 groups in terms of mean attachment loss at baseline, HIV seropositive subjects had experienced more severe attachment loss localised to the lower incisor region. HIV seropositive subjects had a significantly higher mean % of sites exhibiting suppuration and redness. A distinct subgroup of 9 HIV seropositive subjects with widespread attachment loss was detected, which included those subjects with severely affected lower incisors. Site-specific attachment loss of > or = 3 mm was observed in only 20 sites out of 2814 sites in HIV+subjects observed longitudinally. The incidence of aggressive periodontal disease in this study was lower than anticipated, despite the inclusion of patients with advanced HIV infection or AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Comparison of periodontal disease in HIV seropositive subjects and controls (II). Microbiology, immunology and predictors of disease progression.

The aims of this study were to compare the prevalence of suspected periodontal pathogens in subgingival plaque from 29 HIV seropositive and 27 control subjects and to determine the association of these bacteria with periodontal destruction. Subgingival plaque was collected from the mesiobuccal sites of all teeth, except 3rd molars. Bacteria were identified and enumerated using non-isotopic whole chromosomal DNA probes and a colony lift method. At baseline, HIV seropositive subjects had significantly higher mean % of Porphyromonas gingivalis than control subjects. This difference could be attributed to a subgroup of HIV seropositive subjects with widespread attachment loss. No correlations were observed between the mean %s of DNA probe species and mean attachment loss, CD4 and CD8 T lymphocyte counts or CD4: CD8 ratio. No significant microbiological differences were detected between active and control sites in HIV seropositive subjects on a longitudinal basis. There appeared to be an inverse relationship between the mean %s of P. gingivalis and V. parvula, with respect to progression of HIV infection. The ability of microbiological parameters to predict site-specific breakdown in HIV seropositive subjects requires further investigation.

Bacteria↗
PubMed1995

Equine fescue toxicosis: signs and solutions.

Gravid mares grazing endophyte-infested (E+) tall fescue exhibit increased gestation lengths, agalactia, foal and mare mortality, tough and thickened placentas, weak and dysmature foals, increased sweating during warm weather, reduced serum prolactin and progesterone, and increased serum estradiol-17 beta levels. Also, E+ tall fescue hay is less digestible than endophyte-free (E-) hay. Unlike many other species, horses consuming E+ tall fescue do not exhibit increased body temperature. Young horses consuming only E+ pasture do not gain as well as those consuming E- pasture. There is little difference in gain when the pasture is supplemented with enough concentrate to meet NRC requirements for growth. Neither selenium injections nor supplementing with corn at 50% of the NRC requirements for energy reduces the effects of toxic tall fescue on reproduction and lactation in gravid mares. It seems that the alkaloids of E+ tall fescue are serving as D2 dopamine receptor agonists. This activity would explain their prolactin-lowering effect. Domperidone, a dopamine receptor antagonist, is effective in preventing the signs of tall fescue toxicosis in horses without neuroleptic side effects.

Acremonium↗
PubMed1994

Effect of ergovaline, loline, and dopamine antagonists on rat pituitary cell prolactin release in vitro.

Cultured rat pituitary cells were studied to: determine the effects of ergovaline and loline on in vitro prolactin release; delineate the agonistic activity of these alkaloids at the D2 dopamine receptor, using 2 selective D2 dopamine receptor antagonists; and compare the efficacy of 2 dopamine receptor antagonists in reversing effects of the treatments on in vitro prolactin secretion. Ergovaline reduced in vitro prolactin release by at least 40% (P < 0.05) at concentrations of 10(-4), 10(-6), and 10(-8) M. However, loline reduced (P < 0.05) prolactin release only at the highest concentration, 10(-4) M. Two standard dopamine agonists, dopamine and alpha-ergocryptine, were used to verify that the inhibitory control mechanisms of in vitro prolactin release were intact. Both compounds reduced prolactin release by at least 40% for concentrations of 10(-4), 10(-6), or 10(-8) M. Selective D2 dopamine receptor antagonists (10(-6) M), domperidone and sulpiride, reversed (P < 0.05) the effect of loline on in vitro prolactin release. However, only domperidone (10(-6) M) was able to reverse (P < 0.05) the effect of ergovaline and only at the lowest ergovaline concentration (10(-8) M). Domperidone was more effective (P < 0.05) in reversing the prolactin-suppressing effect of alpha-ergocryptine than was sulpiride. The dose-response curve for domperidone (cubic fit, P < 0.0001) indicated a threshold concentration (10(-7) M) for reversal of alpha-ergocryptine's (10(-8) M) effect on prolactin release. However, at similar concentration of sulpiride (quadratic fit, P < 0.007), a threshold level was not obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗
PubMed1994

Efficacy of domperidone and sulpiride as treatments for fescue toxicosis in horses.

We evaluated the effectiveness of 2 dopamine antagonists as treatments for fescue toxicosis in horses. Sixteen gravid mares were assigned by breed and expected foaling date to 1 of 3 treatment groups: endophyte-infested control; 1.1 mg of domperidone/kg of body weight/d; and 3.3 mg of sulpiride/kg/d. Mares were pastured on endophyte-infected fescue and received 0.454 kg of a corn and dried molasses carrier containing the drug treatment. Treatment started 30 days prior to expected foaling date and continued until parturition. Blood samples were collected, and mammary gland scores were recorded every 5 days. Body weight and body condition scores were obtained every 28 days. Serum was analyzed for prolactin, progesterone, and estradiol-17 beta concentrations. Domperidone-treated mares had shorter (P = 0.09) gestation duration and foaled closer (P = 0.07) to their expected parturition date than did control mares. Mammary gland scores were higher (P < 0.05) for domperidone-treated mares than for control mares. By 4 and 9 days after the start of treatment, serum prolactin concentration was higher (P < 0.05) in domperidone-treated mares and sulpiride-treated mares, respectively, than in control mares. Domperidone- and sulpiride-treated mares had higher (P < 0.05) serum progesterone and lower (P < 0.01) estradiol-17 beta concentrations than did control mares. These results indicate that domperidone may offer considerable potential as a treatment for fescue toxicosis in horses.

Animal Feed↗
PubMed1993

Simultaneous hybridization and subsequent colour detection of subgingival bacterial DNA on colony lifts.

This paper reports the development of a protocol allowing hybridization and detection of DNA fixed to nylon colony lifts from up to three species of bacteria simultaneously. Half ml samples of serial dilutions of pure cooked-meat broth (CMB) cultures of Capnocytophaga ochracea, Actinobacillus actinomycetemcomitans and Prevotella intermedia were grown on trypticase soy blood agar (TSBA) plates for 7 days in an anaerobic chamber. From the same CMBs a further set of dilutions was completed that contained all three species. Samples from these dilutions produced mixed-growth TSBA plates following anaerobic incubation for 7 days. After incubation, colony counts on pure-growth TSBA plates were enumerated by colony counter. Colony counts of C. ochracea, A. actinomycetemcomitans and P. intermedia on mixed-growth TSBA plates were enumerated by nylon colony lift, simultaneous hybridization with non-isotopic whole chromosomal DNA probes and alkaline phosphatase substrates generating three colours. The results indicate that the protocol correctly identified and differentiated between the three species on mixed-growth TSBA plates. The proportions of each species and mean total colony count expected by counting pure plates were in agreement with the proportions of each species and total colony counts enumerated by DNA probes on mixed growth plates. The development of simultaneous hybridization and multicolour detection will result in improved data recovery from dental plaque samples, in addition to reducing the cost and labour required in current colony-lift protocols, without affecting the specificity or sensitivity of the probes used.

Aggregatibacter actinomycetemcomitans↗
PubMed1993

Carcass and meat sensory traits of steers finished on fescue and clover, summer forage, or for different periods in drylot.

During a 3-yr period 184 steers were allotted to five treatment groups. Group 1 steers were pastured on fescue-clover and slaughtered in the spring at approximately 540 d of age. Group 2 steers were pastured on fescue-clover then placed on summer pasture regimens and slaughtered at approximately 620 d of age. Group 3 steers were treated the same as Group 2 then placed in the drylot for 45 d. Group 4 steers were treated the same as Group 2 steers then placed in the drylot for 75 d. Group 5 steers were placed in drylot after weaning and conditioning and were slaughtered at endpoints that corresponded with those for Group 3. Steers selected for slaughter at each endpoint were those evaluated to have reached the most optimum slaughter weight and finish by project personnel. Carcasses of steers from fescue-clover and summer pasture had lower yield grades and a lower quality grade than carcasses of steers from drylot (P < .05). Carcasses of steers from fescue-clover and summer pasture had a more yellow fat covering than carcasses of steers that received a concentrate (Treatments 3, 4, and 5, P < .0001). Fescue-clover- and summer pasture-fed steers had a higher percentage of lean and a lower percentage of fat in the 9-10-11th rib section than did steers that received concentrate (P < .005). Chemical analysis of the lean tissue of the 9-10-11th rib section indicated that summer pasture-fed steers had a lower percentage of ether extract and higher percentage of moisture than the lean tissue from steers that received concentrate (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1993

Fescue toxicosis and its impact on animal agriculture.

Studies of fescue toxicosis have identified several classes of plant/fungal alkaloids that may be responsible for the toxicosis problem of endophyte (Acremonium coenophialum) infected tall fescue (Festuca arundinacea). This review explores the interaction of these alkaloids with the animal's system and attempts to explain the various anomalies of fescue toxicosis through discussion of both in vitro and in vivo experiments.

Acremonium↗
PubMed1992

A preliminary study of growth, serum prolactin and reproductive performance of beef heifers grazing Acremonium coenophialum -infected tall fescue.

In an experiment with a 2x2 factorial arrangement of treatments, 32 virgin Angus heifers were used to study effects of tall fescue endophyte Acremonium coenophialum and energy supplementation on reproductive performance. Treatments were feeding of endophyte-free (EF) or endophyte-infected (EI) tall fescue without (0%) and with energy supplementation at one percent group mean body weight (1%). Blood samples were collected at 28-day intervals for prolactin (PRL). Starting 21 days before the breeding season, blood was also collected weekly for progesterone (P(4)) and PRL. After 99 days of grazing, heifers received Syncro-Mate-B (SMB) and were then artificially inseminated over a 30-day period. Heifers on EI-0% had a lower (P<0.05) average final body weight. Highest average daily gain was observed in heifers fed EF-1% (0.98 kg/day), whereas, heifers fed EI-0% had lowest average daily gain (0.53 kg/day; P<0.05). Endophyte-infected fescue depressed serum PRL concentrations (171 and 143 ng/ml vs 70 and 85 ng/ml; EF-0% and EF-1% vs EI-0% and EI-1%, respectively; P<0.05). No differences were observed among treatments in luteal activity before or after SMB, in pregnancy rates after a synchronized estrus or in overall pregnancy rates during the 30-day breeding season. Endophyte-infected fescue decreased average daily gain and depressed serum concentrations of prolactin, but had no effect on reproductive performance as measured in this study.

Journal Article↗
PubMed1992

The effect of alkaloids and seed extracts of endophyte-infected tall fescue on prolactin secretion in an in vitro rat pituitary perfusion system.

The objective of this research was to measure the effects of endophyte-infected tall fescue seed extract and various alkaloids associated with the endophyte on in vitro prolactin secretion by rat hemipituitaries. Rat anterior pituitaries (AP) were dissected into halves and placed in temperature-controlled culture chambers (37 degrees C). The tissue was perfused with culture media at a flow rate of 12 mL/h. After perfusion for at least 90 min with control media, AP halves were exposed to their respective treatments for 15 min before they were returned to the control media. The treatments for Exp. 1 were .01 micrograms of alpha-ergocryptine/mL of culture medium, .01 microgram of ergonovine/mL of culture medium, .01 gram-equivalents of endophyte-infected tall fescue seed/mL of culture medium, and .01 gram-equivalents of endophyte free tall fescue seed/mL of culture medium. Treatments for Exp. 2 consisted of 10(-4), 10(-6), and 10(-8) M concentrations of perloline, N-formyl loline, N-acetyl loline, N-methyl loline, and alpha-ergocryptine. alpha-Ergocryptine suppressed (P less than .10) prolactin secretion in both experiments. Ergonovine and perloline both stimulated (P less than .10) prolactin secretion. The loline alkaloids (N-formyl loline, N-acetyl loline, N-methyl loline) had no effect on prolactin secretion. The endophyte-infected seed extract treatment suppressed (P less than .10) prolactin secretion. The endophyte-free seed extract treatment had no effect on prolactin secretion. In Exp. 2, prolactin secretion from AP responded to alpha-ergocryptine treatment in a dose-dependent fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acremonium↗
PubMed1991

Effect of ammonium carbamate on nutritive and preservative characteristics of high-moisture coastal bermudagrass hay.

Two studies evaluated the effects of ammonium carbamate (AC) on preservation and digestibility of high-moisture (HM) Coastal bermudagrass (Cynodon dactylon) hay. A 3 X 7 factorial arrangement of treatments in a completely random design was used to estimate the efficacy of AC in laboratory conditions. Treatments were 25, 30, or 35% moisture (M) forage treated with levels (L) of 0, 1.14, 2.28, 3.42, 4.56, 5.70, or 6.84% AC. Nitrogen in forage increased (P less than .01) linearly due to M and L. There was a linear decrease (P less than .01) in ADF N due to M. Neutral detergent fiber decreased (P less than .01) linearly as M increased and increased (P less than .01) linearly with increased L. Acid detergent fiber decreased (P less than .01) linearly due to L. There was an M X L interaction (P less than .01) for hemicellulose (HC) concentrations and total aerobic fungal counts. The digestibility of HM hay treated with a product (ACNH) containing 57% AC was compared to that of untreated hay (UH) and UH plus urea (UHU) when fed to lambs (four lambs per treatment). Digestibility of NDF and hemicellulose (P less than .01) and ADF (P less than .05) was increased for ACNH forage compared with UH or UHU. Ammonium carbamate seems to be beneficial for preserving HM forage, and an admixture containing ammonium carbamate is effective for increasing the digestibility of Coastal bermudagrass hay.

Analysis of Variance↗
PubMed1990

Fine needle aspiration and frozen section of salivary gland lesions.

This report examines the role of fine needle aspiration (FNA) and frozen section (FS) examination in the management of salivary gland lesions, and is based on a review of 58 cases. FNA specimens were first classified as nonneoplastic, or as benign or malignant neoplasms. Identification of specific morphologic type of neoplastic lesions was attempted. Overall accuracy for assigning cases was 86%. Specific accuracy (histologic type of neoplasms predicted by FNA) was 72%. No inflammatory lesion was incorrectly diagnosed as neoplasm. Eight patients with histologically documented neoplasm had aspirates classified as nonneoplastic because the sample obtained was not representative. These data indicate that FNA is a highly specific method for identifying benign and malignant neoplasms. Applications of salivary gland FNA include (1) identification of nonneoplastic lesions that may respond to nonsurgical management, (2) identification of neoplasms that represent lymph node metastases rather than primary lesions of the salivary gland, (3) preliminary identification of lymphomas, and (4) preliminary separation of benign and malignant neoplasms.

Biopsy, Needle↗
PubMed1989

Influence of phospholipids on ruminal fermentation in vitro and on nutrient digestion and serum lipids in sheep.

Phospholipid supplements were incubated in vitro or fed to sheep to determine how they affected ruminal fermentation, nutrient digestion and serum lipid concentration. In vitro, deoiled soybean lecithin added to hay increased (P less than .05) total VFA concentration but had no effect on fiber digestion in four of five trials. Purified phospholipid (synthetic phosphatidylethanolamine), however, had little effect on in vitro hay fermentation when tested at four levels (0, 10, 20 or 30 mg) in three separate trials. Deoiled soybean lecithin disappeared in vitro at two rates, 12.9 and .66%/h for the fast- and slow-degrading fractions, respectively. Compared with 2.4% corn oil supplements, 5.2% soybean lecithin added to sheep diets (56% concentrate) reduced (P less than .05) energy, fiber and nitrogen digestibilities. Crude lecithin reduced (P less than .05) energy digestibility more than deoiled lecithin. Both types of lecithin increased (P less than .05) serum nonesterified fatty acid concentrations but had no effect on serum glucose, cholesterol or triglyceride concentrations compared with the corn oil diet. In summary, phospholipids had different effects on ruminal fermentation, depending on their source. None had a beneficial effect on fiber digestion. Phospholipids are degraded in the rumen and inhibit digestion in a manner similar to that of the commercial fats and oils.

Animals↗