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Biomedical subjects

K A Merritt

Publications and source records attributed to K A Merritt.

15 recordsLinked to original sources
PubMed2005

Examination of synovial fluid and serum following intravenous injections of hyaluronan for the treatment of osteoarthritis in dogs.

A randomized, blinded, prospective clinical trial was performed to determine the effects of intravenous (i.v.) administration of hyaluronan sodium (HA) on serum glycosaminoglycans (GAG) concentrations, synovial fluid (SF) hyaluronan concentrations and viscosity in dogs treated for unilateral rupture of the cranial cruciate ligament. Twenty-two dogs undergoing tibial plateau leveling osteotomy were used in this study. Synovial fluid from both stifles and serum were collected prior to surgery and at 2, 4, and 8 weeks following surgery. Dogs received either 1.0 ml (10 mg) of sodium hyaluronate (treatment group 1; n = 10) or equal volume of 0.9% NaCl (treatment group 2; n = 12), i.v. immediately, 2 and 4 weeks following surgery. Synovial fluid viscosity was evaluated using a magnetically driven, acoustically tracked, translating-ball rheometer. Synovial fluid HA disaccharide content was measured by fluorophore-assisted carbohydrate electrophoresis. Serum GAG concentrations were measured by alcian blue spectrophotometric assay. Data were analyzed using a Wilcoxon sign rank test (p < 0.05). Mean +/- SD viscosity (cP) was significantly higher (p = 0.011) in SF obtained from the intact stifle (450 +/- 604.1) than injured (54.8 +/- 60.8) prior to surgery. Mean +/- SD HA concentrations (ug/ml) were significantly higher (p = 0.02) in synovial fluid obtained from the injured stifles (281.4 +/- 145.9) than intact stifles (141.6 +/- 132.5). No significant difference was noted within or between treatment groups in SF viscosity, HA concentrations, or serum GAG concentrations at any time following surgery. Stifles with cranial cruciate ligament insufficiency had significant alterations in SF viscosity and HA concentrations.

Adjuvants, Immunologic↗
PubMed2002

Disposition of oral clarithromycin in foals.

Clarithromycin offers numerous advantages over erythromycin and thus, is an attractive alternative for the treatment of Rhodococcus equi infections in foals. The disposition of clarithromycin was investigated in 6 foals after intragastric administration at a dose of 10 mg/kg body weight. Detectable serum concentrations of clarithromycin were found in 3 of 6 foals at 10 minutes and in all foals by 20 minutes post-administration. Time to peak serum concentration (Tmax) was 1.5 hours and peak serum concentration (Cmax) was 0.92+/-0.17 microg/ml. Mean serum concentrations decreased to 0.03 microg/ml at 24 h. No adverse reactions were noted during or after IG administration in any of the foals. Based on the pharmacokinetic parameters, the MIC90 of R. equi isolates, and predicted steady state concentrations, an oral dose of 7.5 mg/kg given every 12 hours would appear appropriate for the treatment of R. equi infections in foals.

Actinomycetales Infections↗
PubMed2001

Pharmacokinetics of azithromycin and concentration in body fluids and bronchoalveolar cells in foals.

OBJECTIVE: To determine the pharmacokinetics of azithromycin and its concentration in body fluids and bronchoalveolar lavage cells in foals. ANIMALS: 6 healthy 6- to 10-week-old foals. PROCEDURE: Azithromycin (10 mg/kg of body weight) was administered to each foal via i.v. and intragastric (i.g.) routes in a crossover design. After the first i.g. dose, 4 additional i.g. doses were administered at 24-hour intervals. A microbiologic assay was used to measure azithromycin concentrations in serum, peritoneal fluid, synovial fluid, pulmonary epithelial lining fluid (PELF), and bronchoalveolar (BAL) cells. RESULTS: Azithromycin elimination half-life was 20.3 hours, body clearance was 10.4 ml/min x kg, and apparent volume of distribution at steady state was 18.6 L/kg. After i.g. administration, time to peak serum concentration was 1.8 hours and bioavailability was 56%. After repeated i.g. administration, peak serum concentration was 0.63 +/- 0.10 microg/ml. Peritoneal and synovial fluid concentrations were similar to serum concentrations. Bronchoalveolar cell and PELF concentrations were 15- to 170-fold and 1- to 16-fold higher than concurrent serum concentrations, respectively. No adverse reactions were detected after repeated i.g. administration. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of pharmacokinetic values, minimum inhibitory concentrations of Rhodococcus equi isolates, and drug concentrations in PELF and bronchoalveolar cells, a single daily oral dose of 10 mg/kg may be appropriate for treatment of R. equi infections in foals. Persistence of high azithromycin concentrations in PELF and bronchoalveolar cells 48 hours after discontinuation of administration suggests that after 5 daily doses, oral administration at 48-hour intervals may be adequate.

Administration, Oral↗
PubMed2001

Pharmacokinetics of orbifloxacin and its concentration in body fluids and in endometrial tissues of mares.

Pharmacokinetics and distribution of orbifloxacin into body fluids and endometrium was studied in 6 mares after intragastric (IG) administration at a single dose rate of 7.5 mg/kg body weight. Orbifloxacin concentrations were serially measured in serum, synovial fluid, peritoneal fluid, urine, cerebrospinal fluid, and endometrial tissues over 24 hours. Minimum inhibitory concentrations of orbifloxacin were determined for 120 equine pathogens over an 11-month period. The mean peak serum concentration (Cmax) was 2.41+/-0.30 microg/mL at 1.5 hours after administration and decreased to 0.17+/-0.01 microg/mL (Cmin) at 24 hours. The mean elimination half-life (t1/2) was 9.06+/-1.33 hours and area under the serum concentration vs time curve (AUC) was 20.54+/-1.70 mg h/L. Highest mean peritoneal fluid concentration was 2.15+/-0.49 microg/mL at 2 hours. Highest mean synovial fluid concentration was 1.17+/-0.28 microg/mL at 4 hours. Highest mean urine concentration was 536.67+/-244.79 microg/mL at 2 hours. Highest mean endometrial concentration was 0.72+/-0.23 microg/g at 1.5 hours. Mean CSF concentration was 0.46+/-0.55 microg/mL at 3 hours. The minimum inhibitory concentration of orbifloxacin required to inhibit 90% of isolates (MIC90) ranged from < or = 0.12 to > 8.0 microg/mL, with gram-negative organisms being more sensitive than gram-positive organisms. Orbifloxacin was uniformly absorbed in the 6 mares and was well distributed into body fluids and endometrial tissue. At a dosage of 7.5 mg/kg once a day, many gram-negative pathogens, such as Actinobacillus equuli, Escherichia coli, Pasteurella spp., and Salmonella spp. would be expected to be susceptible to orbifloxacin.

Animals↗
PubMed2000

Capillary zone electrophoresis for the determination of atovaquone in serum.

A rapid and simple capillary zone electrophoresis (CZE) method has been developed for the determination of atovaquone in serum. The drug was extracted from equine serum-chloroform (1:3, v/v) at greater than 80% recovery and assayed in buffer containing 25 mM sodium borate (pH 9.1) and 25% acetonitrile. A 100 microm I.D. fused-silica capillary was used and the detection was by UV-diode array at 254 nm; the migration time was approximately 8 min. Intra- and inter-assay variabilities were less than 7.8% and 5.8%, respectively, and the accuracy of the assay (expressed as % bias) ranged from 4.5 to -5.2%. The working assay range was from 2 to 100 microg/ml. This sensitivity could be increased by concentrating during the extraction procedure. Replacement of acetonitrile with 75 mM surfactant 3-(dimethyldodecylammonio)propanesulfonate gave similar sensitivity and provided an additional option to facilitate the separation of atovaquone on multiple-drug samples.

Antifungal Agents↗
PubMed2000

Study of intragastric administration of doxycycline: pharmacokinetics including body fluid, endometrial and minimum inhibitory concentrations.

The objectives of this study were to determine the pharmacokinetics and tissue concentrations of doxycycline after repeated intragastric administration, and to determine the minimum inhibitory concentrations (MIC) for equine pathogenic bacteria. In experiment 1, 2 mares received a single intragastric dose of doxycycline hyclate (3 mg/kg bwt). Mean peak serum concentration was 0.22 microg/ml 1 h postadministration. In experiment 2, 5 doses of doxycycline hyclate (10 mg/kg bwt), dissolved in water, were administered to each of 6 mares via nasogastric tube at 12 h intervals. The mean +/- s.e. peak serum doxycycline concentration was 0.32+/-0.16 microg/ml 1 h after the first dose and 0.42+/-0.05 microg/ml 2 h after the fifth dose. The mean trough serum concentrations were > 0.16 microg/ml. Highest mean synovial concentration was 0.46+/-0.13 microg/ml and highest mean peritoneal concentration was 0.43+/-0.07 microg/ml, both 2 h after the fifth dose. Highest urine concentration was mean +/- s.e. 145+/-25.4 microg/ml 2 h after the last dose. Highest endometrial concentration was mean +/- s.e. 1.30+/-0.36 microg/ml 3 h after the fifth dose. Doxycycline was not detected in any of the CSF samples. Mean +/- s.e. Vd(area) was 25.3+/-5.0 l/kg and mean t1/2 was 8.7+/-1.6 h. In experiment 3, minimum inhibitory concentrations of doxycycline were determined for 168 equine bacterial culture specimens. The MIC90 was < or = 1.0 microg/ml for Streptococcus zooepidemicus and 0.25 microg/ml for Staphylococcus aureus. Based on drug concentrations achieved in the serum, synovial and peritoneal fluids and endometrial tissues and MIC values determined in the present study, doxycycline at a dose of 10 mg/kg bwt per os every 12 h may be appropriate for the treatment of infections caused by susceptible (MIC < 0.25 microg/ml) gram-positive organisms in horses.

Animals↗
PubMed2000

Serum concentrations and pharmacokinetics of enrofloxacin after intravenous and intragastric administration to mares.

Serum concentrations and pharmacokinetics of enrofloxacin were studied in 6 mares after intravenous (IV) and intragastric (IG) administration at a single dose rate of 7.5 mg/kg body weight. In experiment 1, an injectable formulation of enrofloxacin (100 mg/mL) was given IV. At 5 min after injection, mean serum concentration was 9.04 microg/mL and decreased to 0.09 microg/mL by 24 h. Elimination half-life was 5.33 +/- 1.05 h and the area under the serum concentration vs time curve (AUC) was 21.03 +/- 5.19 mg x h/L. In experiment 2, the same injectable formulation was given IG. The mean peak serum concentration was 0.94 +/- 0.97 microg/mL at 4 h after administration and declined to 0.29 +/- 0.12 microg/mL by 24 h. Absorption of this enrofloxacin preparation after IG administration was highly variable, and for this reason, pharmacokinetic values for each mare could not be determined. In experiment 3, a poultry formulation (32.3 mg/mL) was given IG. The mean peak serum concentration was 1.85 +/- 1.47 microg/mL at 45 min after administration and declined to 0.19 +/- 0.06 microg/mL by 24 h. Elimination half-life was 10.62 +/- 5.33 h and AUC was 16.30 +/- 4.69 mg x h/L. Bioavailability was calculated at 78.29 +/- 16.55%. Minimum inhibitory concentrations of enrofloxacin were determined for equine bacterial culture specimens submitted to the microbiology laboratory over an 11-month period. The minimum inhibitory concentration of enrofloxacin required to inhibit 90% of isolates (MIC90) was 0.25 microg/mL for Staphylococcus aureus, Escherichia coli, Salmonella spp., Klebsiella spp., and Pasteurella spp. The poultry formulation was well tolerated and could be potentially useful in the treatment of susceptible bacterial infections in adult horses. The injectable enrofloxacin solution should not be used orally.

Absorption↗
PubMed1998

Changes in sulfation patterns of chondroitin sulfate in equine articular cartilage and synovial fluid in response to aging and osteoarthritis.

OBJECTIVES: To determine effects of aging on sulfation of chondroitin sulfate (CS) in articular cartilage and synovial fluid from normal equine middle carpal joints, and to determine whether CS compositional analysis can be used to assess alterations in proteoglycan turnover in degenerative cartilage obtained from horses with carpal osteochondral fractures. SAMPLE POPULATION: Carpal articular cartilage and synovial fluid from 44 cadavers with normal joints and from 16 Thoroughbred racehorses during routine carpal arthroscopic surgery. PROCEDURE: After papain/chondroitinase digestion of cartilage, CS disaccharides (unsulfated disaccharide delta Di0S, and monosulfated disaccharides delta Di4S and delta Di6S) were quantified by capillary zone electrophoresis. The CS was purified from synovial fluid chondroitinase digested, and analyzed. The CS nonreducing terminal residues, N-acetylgalctosamine (galNAc) or glucuronic acid adjacent to a 4-sulfated or 6-sulfated galNAc, were quantified. RESULTS: In cartilage, the delta Di6S-to-delta Di4S ratio increased with age; in degenerative cartilage, this ratio was not significantly different from the normal value. Percentage of delta Di0S decreased with age and was significantly higher in degenerative than in normal cartilage. The galNAc4S and galNAc4,6S represented > or = 96% of the terminal residues. There was a significant decrease in 6-sulfation of the terminal residues in degenerative cartilage. CONCLUSIONS: 6-Sulfation of internal and terminal CS residues increased with age. Cartilage degeneration in racehorses was accompanied by deposition of CS chains with altered sulfation patterns, in normal and diseased joints of horses > 2 years old, synovial fluid CS was not indicative of cartilage CS and may represent turnover products of a subpopulation of proteoglycan within the matrix.

Aging↗
PubMed1995

Screening for child-reported behavioral and emotional problems in primary care pediatrics.

In light of the findings that mother-completed checklists do not adequately reflect children's perceptions of their own adjustment, two child-completed questionnaires were assessed as screening measures for behavioral or emotional problems with 50 children seen for well-child examinations. Case criterion was child-reported DSM-III symptoms through a clinical interview. Support was provided for the Revised Children's Manifest Anxiety Scale but not the Children's Depression Inventory as a child-reported screening measure. Moreover, the findings indicated that both mother-completed and child-completed measures are needed to screen adequately for behavioral or emotional problems of children seen in a primary care pediatric clinic.

Child↗
PubMed1994

Children's memory for a salient medical procedure: implications for testimony.

OBJECTIVE: Protecting sexually abused children hinges on their ability to remember and report events surrounding alleged incidents of abuse. This study was designed to provide information on young children's memory and recall of stressful experiences. METHODOLOGY: Children's memory for features of a voiding cystourethrogram (VCUG) experience were examined because this invasive procedure is similar in many respects to incidents of sexual abuse. The recall performance of 24 3- to 7-year-olds was assessed immediately after the VCUG and after a delay of 6 weeks using a hierarchically structured interview protocol including both open-ended and more specific questions. To assess correlations between recall performance and distress, behavioral and physiological indicators of distress were measured during the procedure. RESULTS: The children remembered 88% of the component features of the VCUG experience at the initial assessment and 83% after 6 weeks. Behavioral and salivary cortisol measures indicated that the children were distressed during the procedure. Although several of the behavioral measures were correlated negatively with the amount of recall, levels of salivary cortisol did not predict the children's recall performance. CONCLUSION: The findings suggest that, under some conditions, young children can provide accurate and detailed reports of personally experienced distressful events.

Child↗
PubMed1993

Mother-child agreement on the child assessment schedule with nonreferred children: a research note.

This study replicated with nonreferred children the finding with psychiatrically referred children that mother-child concordance was a function of symptom type. Low mother-child concordance for internalizing problems and moderate concordance for externalizing problems characteristic of psychiatric samples was found to generalize to nonreferred children. Furthermore, mother-child concordance was also found to be a function of child gender and age. The implications of these findings for screening or assessment of nonreferred children were examined.

Adult↗
PubMed1993

Screening for behavioral and emotional problems in primary care pediatrics.

Case identification indexes based on the mother-completed Missouri Children's Behavior Checklist (MCBC) were compared with pediatrician identification of behavioral and emotional problems in 41 children seen for well-child examinations. Case identification indexes also were examined as a function of child gender and age and maternal education. The criterion was presence of DSM-III diagnoses determined through Child Assessment Schedule interviews of child or mother. The MCBC yielded better case identification indexes and improvements in both overidentification and underidentification rates. Pediatrician identification indexes were directly related to maternal education and MCBC identification indexes were inversely related to child age. The findings indicate the necessity for including child report, as well as mother report, in screening procedures that are incorporated into primary care pediatric practice.

Child↗
PubMed1992

The Missouri Children's Behavior Checklist behavioral classification system: a construct validity study with nonreferred children.

This study provides validity information about the Missouri Children's Behavior Checklist (MCBC) classifications system with nonreferred children. MCBC behavior patterns of 41 children were related to DSM-III symptomatology ascertained through a structured clinical interview, the Child Assessment Schedule, conducted with the mother. The findings indicated that considering the Undifferentiated Disturbance pattern as an indicator of poor adjustment may be unwarranted with nonreferred children.

Child↗
PubMedDate not supplied

Application of the Gosset icterometer to screen for clinically significant hyperbilirubinemia in premature infants.

To evaluate the ability of the Gosset icterometer to identify the need for serum bilirubin measurement in premature infants we compared 269 icterometer readings with simultaneous serum bilirubin determinations in 90 premature infants of < 37 completed weeks of gestation. The relationship between serum bilirubin and icterometer values was different from that described in term infants. Mean serum bilirubin concentrations were lower at each icterometer level in premature infants than those reported in term babies. Neither interobserver variability nor the color balance of ambient light affected icterometry. Bilirubin estimates by first-time users were slightly less accurate than those made by experienced users. The icterometer provides reliable, cost-effective screening for clinically important hyperbilirubinemia in premature babies if a calibration curve specific for those infants is used. This simple device performs as well as electronic bilirubin meters when it is used in this manner.

Bilirubin↗