Pharmacodynamic effects and pharmacokinetic profile of a long-term continuous rate infusion of racemic ketamine in healthy conscious horses

Ketamine (KET) possesses analgesic and anti-inflammatory activity at sub-anesthetic doses, suggesting a benefit of long-term KET treatment in horses suffering from pain, inflammatory tissue injury and/or endotoxemia. However, data describing the pharmacodynamic effects and safety of constant rate infusion (CRI) of KET and its pharmacokinetic profile in nonpremedicated horses are missing. Therefore, we administered to six healthy horses a CRI of 1.5 mg/kg/h KET over 320 min following initial drug loading. Cardiopulmonary parameters, arterial blood gases, glucose, lactate, cortisol, insulin, nonesterified fatty acids, and muscle enzyme levels were measured, as were plasma concentrations of KET and its metabolites using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Levels of sedation and muscle tension were scored. Respiration and heart rate significantly increased during the early infusion phase. Glucose and cortisol significantly varied both during and after infusion. During CRI all horses scored 0 on sedation. All but one horse scored 0 on muscle tension, with one mare scoring 1. All other parameters remained within or close to physiological limits without significant changes from pre-CRI values. The mean plasma concentration of KET during the 1.5 mg/kg/h KET CRI was 235 ng/mL. The decline of its plasma concentration-time curve of both KET and norketamine (NKET) following the CRI was described by a two-compartmental model. The metabolic cascade of KET was NKET, hydroxynorketamine (HNK), and 5,6-dehydronorketamine (DHNK). The KET median elimination half-lives (t1/2alpha and t1/2beta) were 2.3 and 67.4 min, respectively. The area under the KET plasma concentration-time curve (AUC), elimination was 76.0 microg.min/mL. Volumes of C1 and C2 were 0.24 and 0.79 L/kg, respectively. It was concluded that a KET CRI of 1.5 mg/kg/h can safely be administered to healthy conscious horses for at least 6 h, although a slight modification of the initial infusion rate regimen may be indicated. Furthermore, in the horse KET undergoes very rapid biotransformation to NKET and HNK and DHNK were the major terminal metabolites.

Detection, quantification and confirmation of anabolic steroids in equine plasma by liquid chromatography and tandem mass spectrometry

Anabolic androgenic steroids are related to the male sex hormones and are abused in equine sports. In an effort to deter the abuse of anabolic steroids, a sensitive LC-MS/MS method was developed for detection, quantification and confirmation of eight major anabolic steroids (testosterone, normethandrolone, nandrolone, boldenone, methandrostenolone, tetrahydrogestrinone (THG), trenbolone, and stanozolol) in equine plasma. Formation of solvent adduct ions of the analytes was observed under electrospray ionization (ESI) conditions, and desolvation of the solvent adduct ions by source collision-induced decomposition (CID) increased the abundance of the [M+H]+ ions as well as the multiple-reaction monitoring (MRM) signals. ESI (+) and APCI (+) were compared with respect to sensitivity for the analytes and the former provided better sensitivity. The matrix effect on ion suppression or enhancement was evaluated, and was negligible. Confirmation of the analytes was performed using criteria of three ion transitions and LC retention time of each analyte. The limit of detection (LOD) and quantification (LOQ) was 25 pg/mL. The limit of confirmation (LOC) was 25 pg/mL for boldenone; 50 pg/mL for normethandrolone, nandrolone, and methandrostenolone; and 100 pg/mL for testosterone, THG, trenbolone, and stanozolol. The analytes were evaluated for stability and found to be stable in plasma for 24h at room temperature, 13 days at 4 degrees C, and 34 days at -20 and -70 degrees C. The method was successfully applied to analyses of equine plasma samples for pharmacokinetics study. This method is sensitive and useful for detection, quantification and confirmation of these anabolic steroids in equine plasma.

[The influence of neck-dissection operations on cervical and cerebral blood circulation]

The authors conducted examination of blood flow velocity in medial cerebral artery using Trans Cranial Doppler method and calculated pulsatility index (PI) in 35 patients after neck dissection operation. Similarly 35 patients after neck dissection had duplex Doppler examination of common and internal carotid arteries performed. Pulsatility and resistance indexes and blood flow capacity were estimated. We compared the results with the control group consisted of 15 patients operated on because of chronic otitis. We confirmed a neck dissection operation influence into cranial and cervical blood flow disturbances as well as relationship between postoperative soft tissue oedema and hemodynamical changes. We didn't found connections between cervical and cerebral blood flow and postoperative complications.

A Phase II trial of nolatrexed dihydrochloride in patients with advanced hepatocellular carcinoma

BACKGROUND

Inoperable hepatocellular carcinoma is an incurable malignancy with no accepted standard therapy. Chemotherapy has demonstrated occasional responses and the need is great for a new and effective agent. Therefore the authors conducted this Phase II trial of a novel thymidylate synthase inhibitor, nolatrexed dihydrochloride (designed using structure-based computer modeling), in patients with advanced hepatocellular carcinoma.

METHODS

Forty-one patients with unresectable or metastatic hepatocellular carcinoma were treated with nolatrexed, which was administered as a 24-hour outpatient intravenous infusion for 5 days at a dose of 795 mg/m2/day as free base (1000 mg/m2/day as salt) during each 21-day cycle. Prophylactic treatment was given for emesis and rash.

RESULTS

Twenty-eight patients received at least 2 courses of treatment and 26 patients were evaluable. Two patients (8%) achieved a partial response and 2 additional patients achieved a minor response that was significant enough to allow surgical resection with curative intent. Fourteen patients (54%) achieved stable disease. The overall median survival was 7 months (10 months among patients who completed 2 cycles) and 1 patient remained free of disease at last follow-up, 37 months after surgery. Toxicity was modest and generally was comprised of stomatitis, nausea, malaise, and rash.

CONCLUSIONS

Nolatrexed appears to have modest biologic activity in hepatocellular carcinoma. Due to the lack of alternative treatments, further study of this drug or an oral equivalent may be warranted.

A multicenter phase I/II dose escalation study of single-dose cidofovir gel for treatment of recurrent genital herpes

A randomized, double-blind, clinic-initiated, sequential dose-escalation pilot study was performed to compare the safety and efficacy of single applications of 1, 3, and 5% cidofovir gel with placebo in the treatment of early, lesional, recurrent genital herpes at five Canadian outpatient sites. Ninety-six patients began treatment within 12 h of lesion appearance and were evaluated twice daily until healing of the lesion occurred. Cidofovir gel at all strengths significantly decreased the median time to negative virus culture in a dose-dependent fashion (3.0 days in the placebo group versus 2.2, 1.3, and 1.1 days in the 1, 3, and 5% cidofovir gel treatment groups, respectively; P = 0.02, 0.0001, and 0.0003, respectively). A trend toward a reduction in the median time to complete healing in association with treatment was present, but the differences were not statistically significant (5.0 days in the placebo group versus 4.3, 4.1, and 4.6 days in the 1, 3, and 5% cidofovir gel treatment groups, respectively). Application site reactions occurred in 3, 5, 19, and 22% of the patients in these four groups, respectively. Treatment-associated lesion recrudescence with delayed healing, which is suggestive of local toxicity, was observed in three patients treated with 5% cidofovir gel and one patient treated with 3% cidofovir gel. In summary, single-dose application of cidofovir gel confers a significant antiviral effect on lesions of recurrent genital herpes. Additional studies are warranted to further identify the optimal efficacious dose of cidofovir in association with the maximum gel strength that can be tolerated.

Quantification of penicillin-G and procaine in equine urine and plasma using high-performance liquid chromatography

A rapid and sensitive method for the extraction and quantification of penicillin-G and procaine in horse urine and plasma samples has been successfully developed. The method involves the use of solid-phase extraction (SPE) for penicillin-G, liquid-liquid extraction (LLE) for procaine, and high-performance liquid chromatography (HPLC) for the quantification of penicillin-G and procaine. The new method described here has been successfully applied in the pharmacokinetic studies of procaine, penicillin-G and procaine-penicillin-G administrations in the horse.

[Transcranial Doppler sonography in radical and function neck dissection]

To evaluate the influence of radical or functional neck dissection on cerebral hemodynamics, pre- and postoperatively TCD sonographic examinations were performed in a group of patients following unilateral radical or bilateral radical/functional neck dissection. Cerebral blood flow velocities (cm/s) and pulsatility index (PI) were studied preoperatively and postoperatively 4, 24 and 48 hours after the operation, using a 2 MHz-pulsed transcranial ultrasonographical system (TCD) with a transtemporal approach to the middle cerebral artery. To exclude the influence of general anaesthesia on cerebral circulation TDC was also performed in a group of patients, following operations under general anaesthesia but not radical nor functional neck dissection. The results of both groups were compared with the data obtained in a control group of healthy persons the same age. The reductions in blood flow velocities and concomitant increases in PI observed during the first postoperative insonation in patients after radical/functional neck dissection reflect a heightened resistance to flow in the arterial cerebral vasculature.

Plasma concentrations of flunixin in the horse: its relationship to thromboxane B2 production

The effects of the intravenous (i.v.) administration of 1.1 mg/kg of flunixin meglumine on thromboxane B2 (TxB2) concentrations were studied in sedentary and 2-year-old horses in training. The baseline TxB2 serum concentrations generated during clotting were 2.89 +/- 0.81, 2.19 +/- 0.25 and 0.88 +/- 0.12 ng/ml for the 2-year-old Thoroughbreds in training, sedentary horses under 10 and over 10 years old, respectively. There was a significant difference in baseline TxB2 concentrations between older and younger horses (P less than 0.005). Significant reduction in TxB2 production from baseline were noted at 1 (P less than 0.01) and 4 h (P less than 0.01) but not at 8 h after flunixin administration. The percent reduction in serum TxB2 concentration at 1 h after the administration of flunixin was 68.6 +/- 7.3 and 45.2 +/- 6.8 for the training and sedentary horses, respectively; the differences were significant (P less than 0.04). Serum concentrations of TxB2 returned to baseline values by 12-16 h after flunixin administration. The results of this study indicate a difference in the TxB2 concentrations of older vs. younger horses and a difference in the suppression of TxB2 after the administration of flunixin in 2-year-old Thoroughbreds in training compared to sedentary horses. The results of this study suggest that the detection of low concentrations of flunixin in urine 24 h post-administration may not represent pharmacologic effective concentrations of flunixin in plasma.

[Cerebral infarction--a general-medical problem]

A knowledge of events accompanying the acute coronary failure may help understanding the acute cerebral blood flow insufficiency leading to brain infarction. Cerebral blood flow should be treated as an integral part of the systemic blood circulation. It is of importance when the disease produces lesions to the vascular wall, and the brain looses its autoregulation functions. In such a situation every extracerebral disorders--even slight--may produce extensive lesions to nervous tissue. Therefore, the treatment of the acute cerebral circulation failure requires proper functioning of all factors which may affect hemodynamics and tissue metabolism. Duration of cerebral flow disorders plays an important role in the avoidance of unfavourable complications such as brain infarction. Therefore, every physician is obliged to undertake any possible actions preventing such complications.

[Physical activity in acute cerebrovascular insufficiency]

It was noted that physical activity of 1052 patients hospitalized for the acute cerebral flow failure due to atheromatosis is an important indicator of the cerebral ischemia. Extension of ischemia evaluated on the basis of physical activity enables to foresee possible improvement and survival. Authors' own classification of physical activity may be helpful in the monitoring of cerebral flow failure therapy.

Effect of NaCl-induced osmotic stress on intracellular concentrations of glycine betaine and potassium in Escherichia coli, Enterococcus faecalis, and staphylococci

Staphylococci are more salt tolerant than are enterococci or Escherichia coli. They have a more rigid cell wall and higher internal turgor pressure. The mechanisms of NaCl-induced osmotic tolerance among these bacteria were examined by determining the generation of osmoprotective activity of cellular extracts and intracellular concentrations of glycine betaine and potassium (K+) in response to graded amounts of NaCl. Staphylococci as well as E. coli were shown to require choline or glycine betaine to achieve maximal salt tolerance. In response to 0.9 mol/L NaCl, E. coli exhibited a marked increase in osmoprotective activity, a 168-fold rise in glycine betaine, and a 2.3-fold rise in K+. Enterococcus faealis exhibited a small increase in osmoprotective activity, a 9.3-fold increase in glycine betaine, and a twofold increase in K+. In contrast, strains of Staphylococcus aureus, S. epidermidis, and S. saprophyticus were found to have considerably greater osmoprotective activity, glycine betaine, and K+ than other organisms, even in the absence of external osmotic stress. Glycine betaine rose in some strains, but K+ remained virtually unchanged as the concentration of NaCl was increased. The high concentrations of glycine betaine and K+ in staphylococci, even in the absence of osmotic stress, may explain in part their remarkable salt tolerance and high turgor pressure.

Effect of hydrogen peroxide on growth of Candida, Cryptococcus, and other yeasts in simulated blood culture bottles

The addition of hydrogen peroxide to blood contained in liquid culture medium increased the dissolved-O2 partial pressure in direct proportion to the volume injected. The effect of hydrogen peroxide on the growth of subcultured clinical isolates of Candida albicans, Cryptococcus neoformans, Torulopsis glabrata, and other yeasts and on the growth of blood culture isolates of representative pathogenic bacteria was compared with its effect on their growth in vented and unvented stationary bottles. C. albicans and C. neoformans grew significantly better in bottles to which hydrogen peroxide had been added than in vented or unvented bottles. The advantage of hydrogen peroxide over venting was most marked with several slowly growing strains. Similar results were obtained in shaker cultures with strains of C. albicans which were inoculated directly from positive blood cultures. The effect of hydrogen peroxide tended to diminish during serial passage. T. glabrata grew less well when hydrogen peroxide was added, perhaps because of the absence of oxidase. The growth of Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis was not significantly inhibited or augmented by the addition of hydrogen peroxide. The growth of Escherichia coli was inhibited slightly. The value of the addition of hydrogen peroxide to blood cultures to improve the isolation of yeasts needs to be established by a clinical trial which would compare this method with established methods.

Comparison of SCAN results with other auditory and language measures in a clinical population

This study was conducted to compare results of SCAN: A Screening Test for Auditory Processing Disorders with other central auditory and language tests. The SCAN, Staggered Spondee Word test (SSW), Competing Sentence test, Peabody Picture Vocabulary Test (PPVT), and the Clinical Evaluation of Language Fundamentals-Revised (CELF-R) were administered to 155 children between the ages of 6 and 15 years. All subjects were referred for possible auditory or language processing disorders. Results showed significant correlations between the SCAN, SSW, and Competing Sentence test results except for Filtered Word and Auditory Figure Ground subtests of SCAN that were not significantly correlated with the Competing Sentence Test. Significant correlations also existed between SCAN and the PPVT, but there were no significant correlations between SCAN and the CELF-R subtests. Patterns of responses according to histories of Attention Deficit Disorders were also found.

Infectious circular DNA of human adenovirus type 5: regeneration of viral DNA termini from molecules lacking terminal sequences

A series of plasmids containing the entire human adenovirus genome with viral DNA termini joined 'head to tail' has been isolated. Several plasmids were able to generate infectious virus following transfection of human cells in spite of having small deletions and rearrangements at the junctions of termini. One plasmid has lost 2 bp of DNA from one end of the viral genome and 11 bp from the other end yet produced viruses with complete wild-type sequences at both ends of the genome. We propose a model for replication of viral DNA off circular templates in which regeneration of terminal information involves translocation of primer and polymerase during initiation of DNA replication. The model suggests a novel mechanism for extension of the 5' ends of linear DNA molecules which could be applicable to chromosomal telomeres.

Disposition and excretion of flunixin meglumine in horses

The disposition of flunixin meglumine administered IV at a dosage of 1.1 mg/kg was described by a 2-compartment model; the alpha and beta half-lives (t1/2) were 0.61 and 1.5 hours, respectively. When administered IV at a rate of 2.2 mg/kg, the disposition was best described by a 3-compartment model, and the alpha, beta, and lambda t1/2 were 0.16, 1.52, and 6.00 hours, respectively. The zero-time plasma concentrations after flunixin meglumine was administered at 1.1 and 2.2 mg/kg were 9.3 +/- 0.76 and 21.5 +/- 7.4 mg/L, respectively. The bioavailability after oral administration of 1.1 mg/kg was 85.8%. The absorption t1/2 was 0.57 hours, with a peak concentration of 2.50 +/- 1.25 mg/L. The cumulative urinary recoveries for IV and oral administrations were 61.0% and 63.3%, respectively, of the dose for the 12-hour collection period. The final asymptotic points of urine excretion after IV and oral administrations were 406.4 +/- 65.5 and 357.7 +/- 53.5 mg, respectively, which represented 75.5 and 77.5% of the drug accounted for between 30 and 35 hours after administration. Flunixin meglumine was rapidly excreted in urine over a 2- to 4-hour period after drug administration and was highly bound to protein in plasma.

HPLC qualitative amino acid analysis in the clinical laboratories

The authors have developed a rapid system for qualitative amino acid analysis by high-pressure liquid chromatography for use in the clinical laboratory. Reverse-phase, linear gradient, high-pressure liquid chromatography of stable dansyl chloride derivatives is accomplished with a C-18 column over 30 minutes, with ultraviolet detection. The resulting chromatograms are compared with template chromatograms that reflect high normal levels of serum and urine amino acids. Large elevations of amino acids associated with inborn errors of metabolism are easily pinpointed, with identification of specific amino acids made by the relative retention times. This technic makes available a rapid and specific qualitative method for investigation of aminoacidopathies and uses versatile and standard liquid chromatography equipment.

Human adenovirus cloning vectors based on infectious bacterial plasmids

By making use of the fact that human adenovirus DNA circularizes in infected cells, and that circular forms of the viral genome are infectious, we have developed an improved adenovirus-based cloning system. A deletion mutant of adenovirus type 5 (Ad5) with deletions in early regions 1 (E1) and 3 (E3) was converted to a bacterial plasmid which can regenerate infectious virus following transfection into human 293 cells. A single XbaI recognition site in the deleted E3 region serves as a site for the insertion of foreign DNA. We have used this system to clone a number of genes into the Ad5 genome and describe the insertion of the neomycin/G418 resistance marker into Ad5 as an example.