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Biomedical subjects

R R Gronwall

Publications and source records attributed to R R Gronwall.

At least 37 records · Page 2Linked to original sources
PubMed1989

Pharmacokinetics and body fluid and endometrial concentrations of ormetoprim-sulfadimethoxine in mares.

Six healthy adult mares were each given an oral loading dose of ormetoprim(OMP)-sulfadimethoxine (SDM) at a dosage of 9.2 mg of OMP/kg and 45.8 mg of SDM/kg, followed by four maintenance doses of 4.6 mg of OMP/kg and 22.9 mg of SDM/kg, at 24 h intervals. Ormetoprim and SDM concentrations were measured in serum, synovial fluid, peritoneal fluid, cerebrospinal fluid, urine and endometrium. The highest mean serum OMP concentration was 0.92 micrograms/mL 0.5 h after the first dose; the highest mean SDM concentration was 80.9 micrograms/mL 8 h after the first dose. The highest mean synovial fluid concentrations were 0.14 microgram of OMP/mL and 28.5 micrograms of SDM/mL 12 h after the first dose. The highest mean peritoneal fluid concentrations were 0.19 micrograms of OMP/mL 6 h after the first dose and 25.5 micrograms of SDM/mL 8 h after the fifth dose. The highest mean endometrial concentrations were 0.56 micrograms of OMP/g and 28.5 micrograms of SDM/g 4 h after the fifth dose. The mean cerebrospinal fluid concentrations were 0.08 micrograms of OMP/mL and 2.1 micrograms of SDM/mL 5 h after the fifth dose. Mean trough urine drug concentrations were greater than or equal to 0.4 micrograms of OMP/mL and greater than or equal to 172 micrograms of SDM/mL. Two of the mares were each given a single intravenous (IV) injection of OMP and SDM at a dosage of 9.2 mg of OMP/kg and 45.8 mg of SDM/kg. Excitation and muscle fasciculations were observed in both mares after IV administration and all scheduled blood samples could be collected from only one of the two mares.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Concentration of phenylbutazone (PBZ) and 13, 14-dihydro-15 keto PGF(2alpha) (PGFM) in blood and seminal plasma of stallions treated with PBZ.

Three stallions, 3 to 5 yr old and approximately 550 kg bodyweight, were used in a switchback experimental design to study the effect of daily, oral administration of 3g PBZ on the concentrations of PBZ and PGFM in blood (plasma) and seminal plasma (SP). Control and treatment periods were each 24 days' duration. Blood and semen samples were simultaneously collected every three days during these periods. Each stallion served consecutively as a control, treated, control, and treated subject for 24 days in each of the four periods. Concentrations of PBZ were obtained using HPLC and PGFM by specific RIA. Concentrations (mean +/- SE) of PBZ averaged 9.2 +/- 0.12 ug/ml in plasma but were undetectable in SP following the treatments. There was no significant difference in the plasma levels of PGFM between pre- and post- treatment values. However, there was a significant difference (P<0.001) in PGFM concentrations of seminal plasma before and after treatment. Results of this study suggest that daily, oral adminisration of 3g PBZ for 24 days to mature stallions can significantly decrease seminal plasma concentrations of PGFM. The physiological significance of this observation remains speculative.

Journal Article↗
PubMed1986

Pharmacokinetics and body fluid and endometrial concentrations of cefoxitin in mares.

Four healthy adult mares were each given a single injection of sodium cefoxitin (20 mg/kg of body weight, IV), and serum cefoxitin concentrations were measured serially during a 6-hour period. The mean elimination rate constant was 1.08/hour and the elimination half-life was 0.82 hour. The apparent volume of distribution (at steady state) and the clearance of the drug were estimated at 0.12 L/kg and 259 ml/hr/kg, respectively. Each mare and 2 additional mares were then given 4 consecutive IM injections of sodium cefoxitin (400 mg/ml) at a dosage of 20 mg/kg. Cefoxitin concentrations in serum, synovial fluid, peritoneal fluid, CSF, urine, and endometrium were measured serially. After IM administration, the highest mean serum concentration was 23.1 micrograms/ml 30 minutes after the 2nd injection. The highest mean synovial concentration was 11.4 micrograms/ml 1 hour after the 4th injection. The highest mean peritoneal concentration was 10.4 micrograms/ml 2 hours after the 4th injection. The highest mean endometrial concentration was 4.5 micrograms/g 4 hours after the 4th injection. Mean urine concentrations reached 11,645 micrograms/ml. Cefoxitin did not readily penetrate the CSF. Bioavailability of cefoxitin given IM was 65% to 89% (mean +/- SEM = 77% +/- 5.9%). One of the 6 mares developed acute laminitis during the IM experiment.

Animals↗
PubMed1986

Pharmacokinetics of amikacin in pony foals after a single intramuscular injection.

Six healthy pony foals, from 2 to 11 days of age, were given a single IM injection of amikacin sulfate (250 mg/ml) at a dosage rate of 7 mg/kg of body weight. Serum amikacin concentrations were measured serially over a 24-hour period. The mean peak serum concentration was 14.7 micrograms/ml at 0.5 hour. The elimination rate constant for amikacin was 0.24/hour, the elimination half-life was 3.0 hours, and the apparent volume of distribution was 0.58 L/kg.

Amikacin↗
PubMed1986

Pharmacokinetics and body fluid and endometrial concentrations of cephapirin in mares.

Six healthy adult horse mares were each given a single injection of sodium cephapirin (20 mg/kg of body weight, IV), and serum cephapirin concentrations were measured serially over a 6-hour period. The mean elimination rate constant was 0.78 hour-1 and the elimination half-life was 0.92 hours. The apparent volume of distribution (at steady state) and the clearance of the drug were estimated at 0.17 L/kg and 598 ml/hour/kg, respectively. Each mare was then given 4 consecutive IM injections of sodium cephapirin (400 mg/ml) at a dosage level of 20 mg/kg. Cephapirin concentrations in serum, synovial fluid, peritoneal fluid, CSF, urine, and endometrium were measured serially. After IM administration, the highest mean serum concentration was 14.8 micrograms/ml 25 minutes after the 4th injection. The highest mean synovial and peritoneal concentrations were 4.6 micrograms/ml and 5.0 micrograms/ml, respectively, 2 hours after the 4th injection. The highest mean endometrial concentration was 2.2 micrograms/g 4 hours after the 4th injection. Mean urine concentrations reached 7,421 micrograms/ml. Cephapirin did not readily penetrate the CSF. When cephapirin was given IM at the same dose, but in a less concentrated solution (250 mg/ml), serum concentrations peaked at 25.0 micrograms/ml 20 minutes after injection, but the area under the serum concentration-time curve was not significantly different (P greater than 0.05). The bioavailability of the drug was greater than or equal to 95% after IM injection.

Animals↗
PubMed1985

Pharmacokinetics of ticarcillin in the dog.

Five healthy adult dogs were given a single IV dose (40 mg/kg of body weight) of ticarcillin disodium. Serum concentrations were measured serially over a period of 12 hours. Five days later, the drug was administered IM to the dogs at the same dose rate, and serum concentrations were measured serially for 12 hours. The mean peak serum concentration after IM administration was 120.5 micrograms/ml at 1.5 hours. Pharmacokinetic values following IV administration were (i) elimination rate constant = 0.8/hour-1, (ii) half-life = 0.8 hour, (iii) serum clearance = 292 ml/hr/kg, and (iv) apparent volume of distribution = 347 ml/kg. Estimated values after IM administration were (i) elimination rate constant = 0.6/hour, (ii) half-life = 1.1 hours, (iii) serum clearance = 218 ml/hr/kg, and (iv) apparent volume of distribution = 345 ml/kg; only the elimination rate constants were significantly different between the 2 routes of administration.

Animals↗
PubMed1985

Serum concentrations of gentamicin in cats.

Twenty-one adult cats, allotted into 2 groups, were given gentamicin sulfate at dosages of either 5.0 mg/kg of body weight or 2.5 mg/kg as a single IM injection. During a 24-hour period, serum concentrations of gentamicin were measured serially, using a fluorescence immunoassay. The mean peak serum concentration of gentamicin in cats given 5.0 mg/kg was 23.1 micrograms/ml at postinjection hour (PIH) 0.5; thereafter, the mean serum concentration steadily decreased to 2.0 micrograms/ml at PIH 24. The mean peak serum concentration for cats administered 2.5 mg/kg was 9.1 micrograms/ml at PIH 0.5; thereafter, the mean serum concentration steadily decreased to 1.3 micrograms/ml at PIH 12. Serum therapeutic concentrations, without exceeding toxic concentrations, were attained at the 2.5 mg/kg dosage.

Animals↗
PubMed1984

Amikacin sulfate in mares: pharmacokinetics and body fluid and endometrial concentrations after repeated intramuscular administration.

Six mares were given 5 IM injections (at 12-hour intervals between doses) of amikacin sulfate at a dosage of 7 mg/kg of body weight. Serum amikacin concentrations were measured serially throughout the study; synovial, peritoneal, endometrial, and urine concentrations were determined after the last injection. Amikacin concentrations of the CSF were measured serially in 3 of the 6 mares; 1 of the 3 mares had septic meningitis. Mean serum amikacin concentrations peaked at 1 to 2 hours after IM injection. The highest mean serum concentration was 19.2 micrograms/ml (1.5 hours after the 5th injection). The highest mean synovial concentration was 10.8 micrograms/ml at 2 hours after the 5th injection; the highest mean peritoneal concentration was 16.2 micrograms/ml at 3 hours after the 5th injection. The mean endometrial amikacin concentration was 2.5 micrograms/g (1.5 hours after the 5th injection). Amikacin reached a CSF concentration of 0.97 micrograms/ml in the mare with meningitis, but amikacin was not detected in CSF of healthy mares. Urine concentrations reached 1,458 micrograms/ml. Pharmacokinetic values were estimated after the 1st injection (elimination rate constant = 0.31/hour; half-life = 2.3 hours; apparent volume of distribution = 0.26 L/kg), and after the 5th injection (elimination rate constant = 0.28/hour; half-life = 2.6 hours; apparent volume of distribution = 0.30 L/kg); significant differences were not observed.

Amikacin↗
PubMed1984

Chloramphenicol sodium succinate in the horse: serum, synovial, peritoneal, and urine concentrations after single-dose intravenous administration.

Six healthy adult mares were given a single IV dose (25 mg/kg of body weight) of chloramphenicol sodium succinate. Chloramphenicol concentrations in serum, synovial fluid, peritoneal fluid, and urine were measured serially over a 48-hour period. The highest measured serum chloramphenicol concentration was 6.21 micrograms/ml at 0.5 hour. Chloramphenicol was detected in synovial and peritoneal fluids, with mean peak concentrations of 3.89 micrograms/ml and 3.50 micrograms/ml, respectively, at 0.5 hour. Serum and synovial concentrations declined rapidly and were not measurable at 3 hours. Chloramphenicol could not be detected in peritoneal fluid at 6 hours. The serum half-life was 0.43 hour and the apparent volume of distribution was 2.83 L/kg. Urine concentrations of chloramphenicol peaked at 0.5 hour at 106.72 micrograms/ml and also declined rapidly. The drug could not be detected in the urine at 36 hours.

Animals↗
PubMed1983

Biliary excretion of infused conjugated sulfobromophthalein in sheep heterozygote for the transport defect present in mutant Corriedale sheep.

Biliary excretion of dye was measured in 2 clinically normal and 2 heterozygote Corriedale sheep (the mutant Corriedale is characterized by depressed biliary transport of conjugated sulfobromophthalein (SBP) compounds) during infusion of the preformed glutathione conjugate of SBP. Maximal rates of excretion of conjugated SBP compounds in bile were comparable in heterozygote Corriedale and clinically normal sheep. These 2 heterozygote sheep do not express the biliary transport defect observed in mutant Corriedale sheep during SBP-glutathione infusion.

Animals↗
PubMed1976

Studies on metabolism and effects of estrogen on pituitary prolactin and LH secretion.

The effect of a subcutaneous injection of estradiol on the secretion of pituitary prolactin in the rat and the relationship between serum estradiol level and luteinizing hormone (LH) secretion in mare were reviewed. In addition, the effect of estradiol injection on LH secretion and the metabolism of [14C] estradiol in intact and bile duct fistulated pony mares were studied. Low (0.1 mug/day/rat) to moderate dose (5 mug/day/rat) of estradiol benzoate injected subcutaneously to mature or immature rats significantly increased pituitary content of prolactin and serum prolactin level five- to tenfold. On the other hand, high dose of estradiol (10 mug/day/rat or more) was less effective in stimulating prolactin secretion, and it appeared that progesterone injected concurrently with estradiol had some inhibitory action on the stimulatory effect of estradiol. Studies in pony mares showed that the physiologic level of serum estradiol during proestrus was important for the induction of the ovulatory surge of LH. Intramuscular injection of a low dose (2 or 4 mg/mare) of estradiol was stimulatory, whereas a high dose (8 mg/mare) was inhibitory for LH secretion in pony mares. Results of the estradiol metabolism studies indicated a relatively long half-life for estradiol in the mare. The majority of the [14C] estradiol metabolites appeared in the urine within 24 hr following intravenous injection. Enterohepatic circulation appeared to be important for estradiol metabolism in mare.

Animals↗
PubMed1975

Bile acid kinetics and bile secretion in the pony.

Bile acid pool size and synthesis rate were determined by both isotope-dilution and washout methods in ponies with chronic external biliary fistulas. Bile acid pool size (10.9 mumol/kg) and synthesis rate (11.2 mumol/day per kg) estimated by the isotope-dilution method did not differ significantly from pool size (9.4 mumol/kg) and synthesis rate (9.5 mumol/day per kg) estimated by washout method. Bile acid-dependent and -independent fractions of bile flow, determined by a method that circumvents any inevitable correlation of flow to bile acid secretion due to common factors in both parameters, did not differ from those values obtained by linear regression of bile flow versus bile acid secretion. The choleretic effect of infused chenodeoxycholic acid was higher than that of both endogenous bile acid and infused taurocholic acid.

Animals↗
PubMed1975

Experimental liver diseases.

The use of animal models in the experimental production of liver diseases similar to those of man is still in its infancy. There is a need to discover new models more closely related to counterpart syndromes in man in the fields of hepatorenal syndrome, neonatal jaundice, Wilson's disease, cholelithiasis, viral hepatitis, biliary atresia, and cirrhosis, to mention only a few. With the continued indiscriminate inbreeding of companion animals as well as the planned inbreeding of laboratory animals, there is little doubt that many more will soon be available. The current availability of mutant rats and sheep with bilirubin transport defects has allowed for a better understanding of how organic anions are transported by the liver. Many other currently available experimental animal models herein briefly reviewed have been only superficially studied. It is the intent of this chapter to provide for post-doctoral students an appreciation for the many animal model systems available for experimental hepatic research.

Alkaloids↗
PubMed1972

Renal radial fibrosis in mutant Southdown sheep with congenital hyperbilirubinemia.

Kidneys from 7 mutant Southdown sheep with congenital hyperbilirubinemia, aged from 1 to 5 years were examined. Renal biopsies were taken from another mutant at 3 months and 12 months of age. At 3 months, lesions consisted of thin radial bands of myxomatous tissue in the medullary rays and atrophy of the adjacent collecting tubules. By 1 year collagen had replaced myxomatous tissue. Grossly, the kidneys were normal until 2 years when they became red and gray mottled and stained with bilirubin. The capsules stripped readily to reveal fine granular surfaces in sheep over 2 years of age. On the cut surface of the cortex were 0.5 mm wide radial gray streaks of fibrous tissue. Progressive fibrosis in sheep 2 to 5 years old resulted in a thinning of the cortex. With increasing fibrosis, the number of cystic tubules increased progressively. Protein casts and hyaline droplet degeneration were numerous in sheep over 2 years of age. Plasma cells and lymphocytes were frequently seen in the fibrous bands, and bile pigment was visible in the macrophages in the fibrous tissue and in the epithelium of the proximal tubule cells. Polyuria, low specific gravity urine and reduced effective renal plasma flow and glomerular filtration rates resulted from the replacement of specialized proximal tubule cells by low cuboidal cells, fibrous tissue separating the capillaries from the loops of Henle, destruction of glomeruli and segregation of glomeruli in fibrous bands. The kidney lesions may be determined by the same gene responsible for the hepatic excretion defect for bilirubin.

Age Factors↗