Impact of the blood sampling site on time-concentration drug profiles following intravenous or buccal drug administration.

The aim of this study was to examine the effect of the sampling site on the drug concentration-time profile, following intravenous or buccal (often called 'oral transmucosal') drug administration. Buprenorphine (20 µg/kg) was administered IV or buccally to six cats. Blood samples were collected from the carotid artery and the jugular and medial saphenous veins for 24 h following buprenorphine administration. Buprenorphine concentration-time data were examined using noncompartmental analysis. Pharmacokinetic parameters were compared using the Wilcoxon signed rank test, applying the Bonferroni correction. Significance was set at P < 0.05. Following IV administration, no difference among the sampling sites was found. Following buccal administration, maximum concentration [jugular: 6.3 (2.9-9.8), carotid: 3.4 (1.9-4.9), medial saphenous: 2.5 (1.7-4.1) ng/mL], area under the curve [jugular: 395 (335-747), carotid: 278 (214-693), medial saphenous: 255 (188-608) ng·min/mL], and bioavailability [jugular: 47 (34-67), carotid: 32 (20-52), medial saphenous: 23 (16-55)%] were higher in the jugular vein than in the carotid artery and medial saphenous vein. Jugular venous blood sampling is not an acceptable substitute for arterial blood sampling following buccal drug administration.

c-di-GMP-binding protein, a new factor regulating cellulose synthesis in Acetobacter xylinum.

A protein which specifically binds cyclic diguanylic acid (c-di-GMP), the reversible allosteric activator of the membrane-bound cellulose synthase system of Acetobacter xylinum, has been identified in membrane preparations of this organism. c-di-GMP binding is of high affinity (KD 20 nM), saturable and reversible. The equilibrium of the reaction is markedly and specifically shifted towards the binding direction by K+. The c-di-GMP binding protein, structurally associated with the cellulose synthase, appears to play a major role in modulating the intracellular concentration of free c-di-GMP and thus may constitute an essential factor in regulating cellulose synthesis in vivo.

Detection of prostate cancer by radio-frequency near-field spectroscopy in radical prostatectomy ex vivo specimens.

BACKGROUND: The aim of radical prostatectomy (RP) is the complete removal of the prostate gland with negative surgical margins. The presence of cancer at the surgical margin is associated with higher probability of disease progression. Current methods of intraoperative margin assessment are inaccurate or time-consuming.The study goal was to evaluate the ability of a novel device (Dune Medical Devices) to differentiate between cancer and BPH. METHODS: A total of 49 patients undergoing RP in four medical centers between November 2007 and May 2008 were enrolled in this study.The device was applied to numerous intra- and extra-capsular sites of freshly excised RP specimens. Measurement sites were accurately marked and analyzed histologically. The ability of the device to differentiate between malignant and nonmalignant sites was assessed. RESULTS: A total of 15,156 measurements from 45 patients were analyzed. Differentiation of the intra-capsular malignant sites from extra-capsular nonmalignant sites (bladder neck and apex regions) depends on the cancer feature size. Differentiation was achieved with sensitivity and specificity of 93.6 (95% confidence interval (CI): 88-98) and 94.1 (95% CI: 93-95), respectively, at feature sizes at or >0.8 mm in diameter. The device was able to discriminate between all intra-capsular malignant (with feature sizes down to a few cells) and nonmalignant measurement sites, with sensitivity and specificity of 80.8 (95% CI: 73-87) and 68.4 (95% CI: 67-69), respectively. CONCLUSIONS: First results from a radio-frequency near-field spectroscopy sensor look promising for differentiation between cancer and benign prostate tissue. The sensor's dimensions (radius of ~ 1 mm) and design enable use in open, laparoscopic and robotic RP to evaluate the surgical margins intraoperatively.

Pharmacokinetics of tramadol in horses after intravenous, intramuscular and oral administration.

Tramadol is a centrally acting analgesic drug that has been used clinically for the last two decades to treat moderate to moderately severe pain in humans. The present study investigated tramadol administration in horses by intravenous, intramuscular, oral as immediate-release and oral as sustained-release dosage-form routes. Seven horses were used in a four-way crossover study design in which racemic tramadol was administered at 2 mg/kg by each route of administration. Altogether, 23 blood samples were collected between 0 and 2880 min. The concentration of tramadol and its M1 metabolite were determined in the obtained plasma samples by use of an LC/MS/MS method and were used for pharmacokinetic calculations. Tramadol clearance, apparent volume of distribution at steady-state, mean residence time (MRT) and half-life after intravenous administration were 26+/-3 mL/min/kg, 2.17+/-0.52 L/kg, 83+/-10 min, and 82+/-10 min, respectively. The MRT and half-life after intramuscular administration were 155+/-23 and 92+/-14 min. The mean absorption time was 72+/-22 min and the bioavailability 111+/-39%. Tramadol was poorly absorbed after oral administration and only 3% of the administered dose was found in systemic circulation. The fate of the tramadol M1 metabolite was also investigated. M1 appeared to be a minor metabolite in horses, which could hardly be detected in plasma samples. The poor bioavailability after oral administration and the short half-life of tramadol may restrict its usefulness in clinical applications.