Pharmacokinetics of intra-articular betamethasone sodium phosphate and betamethasone acetate and endogenous hydrocortisone suppression in exercising horses.

To the date, no reports exist of the pharmacokinetics (PK) of betamethasone (BTM) sodium phosphate and betamethasone acetate administered intra-articular (IA) into multiple joints in exercising horses. The purpose of the study was to determine the PK of BTM and HYD concentrations in plasma and urine after IA administration of a total of 30 mg BTM. Eight 4 years old Thoroughbred mares were exercised on a treadmill and BTM was administered IA. Plasma and urine BTM and HYD were determined via high performance liquid chromatography spectrometry for 6 weeks. Concentration-time profiles of BTM and HYD in plasma and urine were used to generate PK estimates for non-compartmental analyses and comparisons among times and HYD concentrations. BTM in plasma had greater Tmax (Tmax 0.8 h) vs. urine (Tmax 7.1 h). Urine BTM concentration (ng/mL) and amount (AUClast ; h × ng/mL) were greater than plasma. HYD was suppressed for at least 3 days (<1 ng/mL) for all horses. The time of last quantifiable concentration of BTM (Tlast ; hour) was not significantly different in plasma than urine. Use of highly sensitive HPLC-MS/MS assays enabled early detection and prolonged and consistent determination of BTM in plasma and urine.

Direct delayed human adenoviral BMP-2 or BMP-6 gene therapy for bone and cartilage regeneration in a pony osteochondral model.

OBJECTIVE: To evaluate healing of surgically created large osteochondral defects in a weight-bearing femoral condyle in response to delayed percutaneous direct injection of adenoviral (Ad) vectors containing coding regions for either human bone morphogenetic proteins 2 (BMP-2) or -6. METHODS: Four 13mm diameter and 7mm depth circular osteochondral defects were drilled, 1/femoral condyle (n=20 defects in five ponies). At 2 weeks, Ad-BMP-2, Ad-BMP-6, Ad-green fluorescent protein (GFP), or saline was percutaneously injected into the central drill hole of the defect. Quantitative magnetic resonance imaging (qMRI) and computed tomography (CT) were serially performed at 12, 24, and 52 weeks. At 12 (one pony) or 52 weeks, histomorphometry and microtomographic analyses were performed to assess subchondral bone and cartilage repair tissue quality. RESULTS: Direct delivery of Ad-BMP-6 demonstrated delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) and histologic evidence of greater Glycosaminoglycan (GAG) content in repair tissue at 12 weeks, while Ad-BMP-2 had greater non-mineral cartilage at the surface at 52 weeks (p<0.04). Ad-BMP-2 demonstrated greater CT subchondral bone mineral density (BMD) by 12 weeks and both Ad-BMP-2 and -6 had greater subchondral BMD at 52 weeks (p<0.05). Despite earlier (Ad-BMP-6) and more persistent (Ad-BMP-2) chondral tissue and greater subchondral bone density (Ad-BMP-2 and -6), the tissue within the large weight-bearing defects at 52 weeks was suboptimal in all groups due to poor quality repair cartilage, central fibrocartilage retention, and central bone cavitation. Delivery of either BMP by this method had greater frequency of subchondral bone cystic formation (p<0.05). CONCLUSIONS: Delivery of Ad-BMP-2 or Ad-BMP-6 via direct injection supported cartilage and subchondral bone regeneration but was insufficient to provide long-term quality osteochondral repair.

A Theoretical Analysis of Enantiomerization in Aromatic Amides.

The mechanisms for enantiomerization in benzamide (B), N,N-dimethylbenzamide (DB), 1-naphthamide (N), and N,N-dimethyl-1-naphthamide (DN) were investigated both in the gas phase and in solution at the MP2-FC/6-311+G(d,p)//B3LYP/6-31+G(d,p) theory level. The effect of solvent (DMSO, chloroform) was taken into account by using the polarizable continuum model-united atom Hartree-Fock (PCM-UAHF) model. Two different kinds of mechanisms were found. The first kind proceeds through rotation about the Ar-CO bond and inversion at the nitrogen atom, while the second one consists of concerted Ar-CO and C-N rotations. Solvent effect destabilizes mostly the transition states (TSs) with concerted rotations owing to the loss of amide conjugation in these structures. According to our results using DMSO and chloroform as solvents, for benzamide, the mechanism through inversion is, respectively, 14.1 and 13.2 kcal mol-1 more favorable than that through concerted rotations. This difference diminishes when a second ring is introduced (11.3 and 10.7 kcal mol-1, respectively, for N) and even more when the hydrogen atoms on N are substituted by methyl groups so that for DB the route through inversion is, respectively, 5.5 and 4.8 kcal mol-1 more favorable than that through concerted Ar-CO and C-N rotations and for DN this difference reduces to 1.1 and 0.6 kcal mol-1, respectively, rendering both mechanisms practically competitive in this case.

Rearrangements involving the phenonium ion: a theoretical investigation.

Rearrangements involving the phenonium ion were investigated by means of a B3LYP/6-311G(d,p) study in which the effect of solvent has been incorporated by using a PCM solvation model. A rationalization of the whole set of experimental facts reported both in the gas phase and in solution was possible thanks to the characterization of protonated benzocyclobutene as a minimum energy structure and, particularly, to the important preferential stabilization in solution of the TS for the isomerization of the phenonium ion to the alpha-methylbenzyl ion, which reduces the Gibbs energy barrier of 26.6 kcal/mol for this process in the gas phase to a more accessible one of 18.7 kcal/mol in solution.

[The levels of knowledge about nonclinical areas which are characteristic of the new model of primary care]. / Grado de conocimiento en áreas no clínicas propias del nuevo modelo de atención primaria.

OBJECTIVE: To evaluate the level of knowledge about the non-clinical areas which characterise the new model of primary care among doctors and nurses who work in primary care teams (PCT); and to identify the most deficient areas of knowledge and the variables associated with these lower levels of knowledge. DESIGN: An observation study of a crossover kind. SETTING: PCTs of Health Area 1 in Madrid. PARTICIPANTS: Doctors and nurses who were working in the 23 PCTs functioning when the study was carried out (321 people). MEASUREMENTS AND MAIN RESULTS: Knowledge was measured by a self-filled, anonymous questionnaire elaborated by a panel of experts. It contained 72 items with correct (C) or false (F) double reply, grouped in 12 basic areas of knowledge relating to the non-clinical aspects which characterise the new model of primary care (PC). A pilot test was done in a PCT in another Area. The data bases were performed on DBASEIII+ and the statistical analysis on SPSS v. 4.0. The required level of knowledge through the questionnaire as a whole was attained by 41.6% of the professionals. An association with the following was noted: Age (p < 0.0001), Profession (p < 0.005), Year that training ended (p < 0.01), Type of contract (p < 0.005), Nature of access to a permanent post (p < 0.0005), postgraduate academic training for doctors (p < 0.001) and Residency in Family and Community Medicine (p < 0.009). The most deficient areas of knowledge were: Evaluation of procedures and programmes (46%), Community Participation (51.6%), the filling-out and standardisation of records (55.2%), and the Evaluation of objectives and quality control mechanisms. CONCLUSIONS: Knowledge of non-clinical areas is low.

Interaction between L-threonine dehydrogenase and aminoacetone synthetase and mechanism of aminoacetone production.

A mixture of threonine dehydrogenase and aminoacetone synthetase will catalyze the conversion of L-threonine to glycine. The overall reaction likely involves the conversion of L-threonine, NAD+, and CoA to glycine, NADH, and acetyl-CoA. Physical separation of L-threonine dehydrogenase from aminoacetone synthetase results in the formation of aminoacetone and CO2 from their substrates. A physical interaction between threonine dehydrogenase and aminoacetone synthetase has been demonstrated by gel permeation chromatography and fluorescence polarization. Polarization of fluorescence measurements of threonine dehydrogenase and aminoacetone synthetase labeled with fluorescein isothiocyanate indicated the formation of a soluble active complex, with an apparent dissociation constant (Kd) of 5-10 nM and an apparent stoichiometry of 2 aminoacetone synthetase dimers/1 threonine dehydrogenase tetramer. Chemical experiments have identified aminoacetone as the enzymatic product of L-threonine dehydrogenase acting on L-threonine. These experiments involved trapping pyrrole derivatives, [3H]NaBH4 reduction, and coupling with plasma amine oxidase. Kinetic experiments also showed NADH, CO2, and aminoacetone to inhibit threonine dehydrogenase in a manner consistent with an ordered Bi-Ter kinetic mechanism. NAD+ is the lead substrate followed by threonine, and the products are released in the order: CO2, aminoacetone, and NADH.