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Biomedical subjects

L E Davis

Publications and source records attributed to L E Davis.

At least 181 records · Page 10Linked to original sources
PubMed1983

Isolation of Trichomonas vaginalis from the respiratory tract of infants with respiratory disease.

Trichomonas vaginalis was isolated from the respiratory tracts of two infants with respiratory disease. Bacterial and viral cultures of tracheal aspirates and nasopharyngeal specimens did not detect bacterial pathogens or viruses; however, T vaginalis was found to be present in inoculated cell cultures. Both infants were delivered vaginally by mothers with known previous episodes of T vaginalis infection. The possibility that this organism may, on occasion, cause respiratory tract disease needs further evaluation.

Delivery, Obstetric↗
PubMed1983

Factors influencing survival and morbidity with very low birth weight delivery.

Factors influencing survival and morbidity in a group of 214 consecutively delivered very low birth weight infants (500 to 1500 g) are examined. The perinatal mortality was 313 per 1000 births. Of 185 live-born, congenitally normal infants, 133 (72%) were discharged alive. Respiratory distress syndrome was the most common form of significant morbidity, occurring in 114 infants (62%). Intraventricular hemorrhage was diagnosed in 38 (21%) of the infants. Neither survival nor morbidity was influenced by the mode of delivery. The current trend of a liberalized policy of cesarean section for the very low birth weight delivery is questioned.

Apgar Score↗
PubMed1983

Distribution of oxytetracycline in the healthy and diseased postpartum genital tract of cows.

Previously determined pharmacokinetic parameters of the disposition of oxytetracycline (OTC) in cows were used to predict an IV priming dose and a rate of constant IV infusion of OTC sufficient to approach steady-state equilibrium of the drug between plasma and genital tissue concentrations in healthy postpartum cows and postpartum cows with endometritis. After 8 hours' constant IV infusion at rates calculated to maintain a plasma concentration of approximately 5 micrograms/ml, the mean concentrations of OTC in plasma (microgram/ml) and tissues (microgram/g) of healthy and infected postpartum cows, respectively, were: plasma, 4.95 and 5.23; uterine tissue, 3.65 and 4.18; and ovarian tissue, 4.57 and 4.53. The mean plasma to genital tissue ratios for healthy and infected postpartum cows, respectively, were 1.38 and 1.31 for uterine tissue and 1.09 and 1.16 for ovarian tissue. There were no significant differences (P greater than 0.28) between healthy and infected postpartum cows in any of the parameters investigated. However, plasma-to-genital tissue ratios of concentrations of OTC in postpartum cows as a group were significantly higher (P less than or equal to 0.03) than those previously determined in cycling cows. Computer-simulated uterine tissue concentrations of OTC, after twice daily IV doses of 11 mg of OTC/kg of body weight, indicated that this dosage regimen would provide postpartum uterine tissue concentrations greater than 5 micrograms/g during most of the dosage interval.

Animals↗
PubMed1983

Distribution of oxytetracycline in genital tract tissues of postpartum cows given the drug by intravenous and intrauterine routes.

Oxytetracycline (OTC) was administered by constant IV infusion to 3 healthy postpartum cows at rates predicted to approach a steady-state plasma concentration of 5 micrograms/ml. After 8 hours of constant IV infusion, genital tissues were surgically removed. The mean plasma-to-tissue ratios of concentrations of OTC were 0.95, 1.33, 1.88, and 1.04 (2 cows only) for caruncles, endometrium, uterine wall, and ovaries, respectively. Differences between the ratios of any 2 of the uterine tissues were statistically significant (P less than 0.05). Intrauterine (IU) infusions of 5.5 mg of OTC/kg were administered to 3 healthy postpartum cows and 3 postpartum cows with metritis. The mean values of the fraction of the drug absorbed from the uteri of cows given IU infusions of OTC were 0.50 and 0.23 for healthy postpartum cows and postpartum cows with metritis, respectively. Concentrations of OTC were high in the caruncles and endometrium of all cows at 24 hours after IU infusions of the drug. Concentrations in the plasma, uterine wall, and ovaries were low, with mean concentrations of OTC in these tissues in postpartum cows with metritis being lower than those in the same tissues of healthy postpartum cows. Computer-simulated genital tissue concentrations of OTC after twice daily IV doses of 11 mg/kg indicated that this dosage regimen would provide postpartum uterine tissue concentrations greater than 5 micrograms/g throughout the dosage interval in all tissues, except the uterine wall.

Absorption↗
PubMed1982

Review of glucocorticoid pharmacology.

Rational glucocorticoid therapy depends on a complicated interplay of many factors. An understanding of the physiology of the hypothalamic-pituitary-adrenal axis, the comparative potencies, duration, and adverse effects of the available corticosteroid bases and their esters, and especially the specific goals of the therapy for a wide variety of diseases facilitates this therapy. It is impossible to make specific dose recommendations for glucocorticoid therapy. Individual patients and their various diseases respond differently to a given dose of glucocorticoid.

Animal Diseases↗
PubMed1982

Effects of chloramphenicol on the development of immune responses to canine distemper virus in beagle pups.

The effect of oral chloramphenicol (CHPC) on the development of immune responses to canine distemper virus (CDV) in Beagle pups was studied. Dogs were treated with CHPC for 14 days at a dose of 50 mg/kg, three times a day. Hematologic changes in CHPC-treated dogs included: polychromasia, anisocytosis, and target cell formation of red blood cells concurrent with vacuolation of lymphocytes and basophilic granule formation in neutrophils. Dogs given this therapy showed normal in vivo and in vitro immune responses after CDV vaccination and survived a virulent CDV challenge, whereas untreated, unvaccinated dogs became ill or died after challenge exposure. The results of this study indicate that CHPC therapy does not interfere with either the prechallenge immune response to attenuated viral antigen or the efficient immune mechanisms invoked during virulent virus challenge.

Animals↗
PubMed1982

Xylazine hydrochloride-induced hyperglycemia and hypoinsulinemia in thoroughbred horses.

The effects of intravenous xylazine (1.1 mg/kg) were studied in six thoroughbred horses (five mares and a stallion). Plasma glucose concentration increased to 168% of control at 45 min and decreased to 112% of control at 180 min. Insulin had decreased to 31% of control at 15 min. Thereafter, insulin concentration increased, reaching its highest concentration at 150 min. The mechanism for these changes is not fully understood and further investigation is indicated.

Animals↗
PubMed1982

Distribution of oxytetracycline in the genital tract of cows.

Pharmacokinetic parameters of the disposition of oxytetracycline (OTC) were investigated in healthy cycling dairy cows after a single IV dose of 22 mg/kg of body weight. The biological half-life of OTC was 6.5 hours. These data were used to predict an IV priming dose and a rate of constant IV infusion of OTC sufficient to approach steady-state equilibrium of the drug between a plasma concentration of approximately 5 microgram/ml and a uterine tissue concentration. After 8 hours' constant IV infusion, the mean plasma concentration of OTC was 4.86 +/- 0.68 microgram/ml and the mean uterine tissue concentration of OTC was 4.50 +/- 0.45 microgram/ml. The mean ratio of plasma-to-uterine tissue OTC concentrations was 1.08. Computer-stimulated IV multiple doses of OTC at 11 mg/kg every 12 hours and 11 mg/kg every 24 hours suggested that the former dosage regimen could provide uterine tissue concentrations greater than 5 microgram/ml during the dosage interval, whereas the latter could provide such concentrations for only the first 12 hours of a 24-hour dosage interval.

Animals↗
PubMed1981

Acute thallium poisoning: toxicological and morphological studies of the nervous system.

Nine days following ingestion of 5 to 10 gm of thallium nitrate, a young man died with severe cranial and peripheral neuropathy, anuria, and heart failure. Ultrastructural examination of nerves obtained on days 7 and 9 demonstrated axonal degeneration with secondary myelin loss. Axons were swollen and contained distended mitochondria and vacuoles. Thallium levels in more than twenty organs and body fluids ranged from below 1.0 to 178 microgram/gm; concentrations in twenty areas of the nervous system ranged from 29 to 140 microgram/gm. The highest brain levels of thallium were found in gray matter. In the thalamus, 87% of the thallium was present in cell sap. Tissue concentrations of thallium did not parallel those reported for potassium, suggesting that thallium distribution differs from potassium distribution in human beings.

Acute Disease↗
PubMed1981

Pharmacokinetic studies of theophylline in dogs.

The pharmacokinetics of theophylline were investigated in dogs following intravenous, single oral, and multiple oral doses of aminophylline. Mean half-life (t1/2) of theophylline following single intravenous administration was 5.7 h and the apparent specific volume of distribution (V'd area) was 0.82 litre/kg. The bioavailability of theophylline was high (91%) following oral administration of aminophylline tablets and the absorption half-life (t1/2ab) was 0.4 h. Theophylline plasma concentrations observed following repeated oral administration of aminophylline tablets were somewhat greater than predicted. This suggests that theophylline plasma concentrations should be monitored and the dosage regimen individually adjusted in critically ill animals.

Animals↗
PubMed1981

Metronidazole: a method for its determination in biological fluids and its disposition kinetics in the dog.

A method for the analytical determination of metronidazole concentrations in biological tissues was developed using high performance liquid chromatography. The procedure was employed to investigate the pharmacokinetics of metronidazole in dogs following intravenous and oral administration (44 mg/kg). The overall elimination rate constant beta was 0.0027 +/- 0.0005 min-1, the apparent specific volume of distribution (V'd) was 0.948 +/- 0.096 L/kg overall clearance (ClB) was 2.49 +/- 0.54 ml/kg/min and the rate constant for absorption Kab was 0.0456 +/- 0.0353 min-1. Oral bioavailability was high but variable (59%-100%). Implications of these data for chemotherapy of infections caused by anaerobic bacteria, trichomonads, and Giardia and for the sensitization of hypoxic neoplastic cells to radiotherapy are discussed.

Administration, Oral↗
PubMed1981

Warfarin in the dog: pharmacokinetics as related to clinical response.

Warfarin was administered intravenously (i.v.) as a single dose of 1.5 mg/kg to healthy dogs and the pharmacokinetic parameters were investigated. Elimination could be described by a one-compartment open model. Values for the elimination half-life and apparent specific volume of distribution were 14.5 +/- 4.1 h and 0.22 +/- 0.04 litre/kg, respectively. Oral maintenance doses were calculated from the data collected following i.v. administration and administered every 12 h for a total of five doses after an initial i.v. loading dose of 1.5 mg/kg. Prothrombin times increased from a control value of 8.6 +/- 0.3 sec to 55.2 +/- 5.2 sec over a period of 96 h. Prothrombin time returned to control values by 62 h after withdrawal of the drug. We propose a dosage regimen of warfarin for anticoagulant therapy in the dog of 0.22 mg/kg to be given orally every 12 h. Prothrombin time should be monitored during therapy and the dose of warfarin modified according to the degree of suppression of coagulation factors desired.

Administration, Oral↗