Efficient biodegradation of the recalcitrant organochlorine pesticide chlordecone under methanogenic conditions

Anaerobic digestion (AD) has long been studied as an effective environmental and economic strategy for treating matrices contaminated with recalcitrant pollutants. In the present work, we investigated the bioremediation potential of AD on organic waste contaminated with chlordecone (CLD), an organochlorine pesticide extensively used in the French West Indies and classified among the most persistent organic pollutants. Digestates from animal and plant origins were supplemented with CLD and incubated under methanogenic conditions for over 40 days. The redox potential and pH monitoring showed that methanogenic conditions were preserved during the entire incubation period despite the presence of CLD. In addition, the comparison of the total biogas generated from digestates with and without CLD demonstrated no adverse effects of CLD on biogas production. For the first time, a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction method, followed by GC-MS and LC-HRMS analyses, was developed to quantify CLD and its main known transformation products (TPs) in AD experiments. A decrease in CLD concentrations was evident to a greater extent under thermophilic conditions (55 °C) compared to mesophilic conditions (37.5 °C) (CLD removal of 85 % and 42 %, respectively, after 40 days of incubation). CLD degradation was confirmed by the detection and quantification of several TPs: 10-monohydroCLD (A1), two dihydroCLDs different from 2,8-dihydroCLD (A3), pentachloroindene (B1), tetrachloroindenes (B2, B3/B4), tetra- and tri-chloroindenecarboxylic acids (C1/C2, C3/C4). Determining TPs concentrations using the QuEChERS method provided an overview of CLD fate in AD. Overall, these results reveal that AD processes can efficiently degrade CLD into several TPs from A, B, and C families while maintaining satisfactory biogas production. They pave the way to developing a scaled-up AD process capable of treating CLD-contaminated organic wastes produced by farming, thus stopping any further transfer of CLD.

Chemical imaging of a Symbiodinium sp. cell using synchrotron infrared microspectroscopy: a feasibility study

The symbiotic relationship between corals and Symbiodinium spp. is the key to the success and survival of coral reef ecosystems the world over. Nutrient exchange and chemical communication between the two partners provides the foundation of this key relationship, yet we are far from a complete understanding of these processes. This is due, in part, to the difficulties associated with studying an intracellular symbiosis at the small spatial scales required to elucidate metabolic interactions between the two partners. This feasibility study, which accompanied a more extensive investigation of fixed Symbiodinium cells (data unpublished), examines the potential of using synchrotron radiation infrared microspectroscopy (SR-IRM) for exploring metabolite localisation within a single Symbiodinium cell. In doing so, three chemically distinct subcellular regions of a single Symbiodinium cell were established and correlated to cellular function based on assignment of diagnostic chemical classes.

Characterization of truck-mounted atomization equipment typically used in vector control

The control of medically important arthropod vectors of human and animal disease is a high priority for both public health and military officials. Because droplet size of pesticide spray material is a critical factor affecting vector control applications, the droplet-size spectra produced by 11 sprayers and 3 spray formulations were evaluated. Droplet-size spectra were measured by a laser diffraction instrument, a hot-wire system, and rotating slides. There were considerable differences in the droplet-size spectra produced by the different sprayers tested. The volume median diameter (Dv0.5) for the water-based sprays ranged from 4.7 to 211 microm, depending on the sprayer, and the percent of spray volume contained in droplets less than 20 microm (%vol <20 microm) ranged between 0.5% and 98.9%. The Dv0.5 measurements for the oil-based sprays ranged from 9.4 to 125.3 microm and the %vol <20 microm ranged between 2.4% and 97.9%. The correlations between the Dv0.5 measured by the laser system (Dv0.5-laser) and the mass median diameter, Sauter diameter, and Dv0.5 measured by the AIMS probe were all significant. Generally, the slide Dv0.5s were numerically similar to the Dv0.5 from the laser system and the Sauter diameter from the Army Insecticide Measuring System probe. There was less consistent agreement between the % <32 microm values obtained from the slides and those from the other 2 samplers. The information presented can be used by applicators to select the sprayer that produces the droplet-size spectra needed for their particular application situation.

PA-457: a potent HIV inhibitor that disrupts core condensation by targeting a late step in Gag processing

New HIV therapies are urgently needed to address the growing problem of drug resistance. In this article, we characterize the anti-HIV drug candidate 3-O-(3',3'-dimethylsuccinyl) betulinic acid (PA-457). We show that PA-457 potently inhibits replication of both WT and drug-resistant HIV-1 isolates and demonstrate that the compound acts by disrupting a late step in Gag processing involving conversion of the capsid precursor (p25) to mature capsid protein (p24). We find that virions from PA-457-treated cultures are noninfectious and exhibit an aberrant particle morphology characterized by a spherical, acentric core and a crescent-shaped, electron-dense shell lying just inside the viral membrane. To identify the determinants of compound activity we selected for PA-457-resistant virus in vitro. Consistent with the effect on Gag processing, we found that mutations conferring resistance to PA-457 map to the p25 to p24 cleavage site. PA-457 represents a unique class of anti-HIV compounds termed maturation inhibitors that exploit a previously unidentified viral target, providing additional opportunities for HIV drug discovery.

Role of a ferredoxin gene cotranscribed with the nifHDK operon in N(2) fixation and nitrogenase "switch-off" of Azoarcus sp. strain BH72

The endophytic diazotroph Azoarcus sp. strain BH72 is capable of infecting rice roots and of expressing the nitrogenase (nif) genes there. In order to study the genetic background for nitrogen fixation in strain BH72, the structural genes of nitrogenase (nifHDK) were cloned and sequenced. The sequence analysis revealed an unusual gene organization: downstream of nifHDK, a ferredoxin gene (fdxN; 59% amino acid sequence identity to R. capsulatus FdxN) and open reading frames showing 52 and 36% amino acid sequence identity to nifY of Pseudomonas stutzeri A15 and ORF1 of Azotobacter vinelandii were located. Northern blot analysis, reverse transcriptase PCR and primer extension analysis revealed that these six genes are located on one transcript transcribed from a sigma(54)-type promoter. Shorter transcripts sequentially missing genes of the 3' part of the full-length mRNA were more abundantly detected. Mutational analyses suggested that FdxN is an important but not the essential electron donor for dinitrogenase reductase. An in-frame deletion of fdxN resulted in reduced growth rates (59% +/- 9%) and nitrogenase activities (81%) in nitrogen-fixing pure cultures in comparison to the wild type. Nitrogenase activity was fully complemented in an fdxN mutant which carried a nifH promoter-driven fdxN gene in trans. Also, in coculture with the ascomycete Acremonium alternatum, where strain BH72 develops intracytoplasmic membrane stacks, the nitrogenase activity in the fdxN deletion mutant was decreased to 56% of the wild-type level. Surprisingly, the fdxN deletion also had an effect on the rapid "switch-off" of nitrogenase activity in response to ammonium. Wild-type strain BH72 and the deletion mutant complemented with fdxN in trans showed a rapid reversible inactivation of acetylene reduction, while the deletion mutant did not cease to reduce acetylene. In concordance with the hypothesis that changes in the redox state of NifH or electron flux towards nitrogenase may be involved in the mechanism of physiological nitrogenase switch-off, our results suggest that the ferredoxin may be a component involved in this process.

Occurrence of three PII-like signal transmitter proteins in the diazotrophic proteobacterium Azoarcus sp. BH72

PII-like signal transmitter proteins are involved in the regulation of ammonium assimilation and nitrogen fixation. We report the identification of three PII-like proteins in the diazotrophic, endophytic proteobacterium Azoarcus sp. BH72, encoded by glnB (monocistronically transcribed) or in the glnKamtB and glnYamtY operons. Phylogenetic analysis revealed that glnB, glnK and glnY represent distinct lineages within the Proteobacteria. A combined approach of two-dimensional gel electrophoresis, Western blotting with paralogue-specific antibodies, N-terminal sequencing and marker exchange mutagenesis allowed us to analyse PII protein expression of Azoarcus sp. BH72 in vivo. GlnK and GlnB were present on all nitrogen sources. Knock-out mutant analysis revealed that GlnB was the only detectable PII protein in a glnK- background, whereas GlnY was only present in a glnK/glnB- double mutant. Nitrogen limitation enhanced transcript abundance of glnK strongly, glnY moderately and glnB not at all in wild-type, glnB-/glnK- or glnK- backgrounds respectively. Phenotypic characterization of knock-out mutants revealed that, unlike in other Proteobacteria, neither glnK nor glnB were essential for nitrogen fixation. As the growth of a double mutant was drastically impaired only on minimal media, both proteins are probably involved in the control of ammonium and nitrate assimilation. The PII-like proteins differed from each other in details of N-sensing. They were covalently modified by uridylylation upon nitrogen limitation, as shown by mass spectrometry; however, the modification patterns in relation to the supplied nitrogen source differed. The novel paralogue GlnY was unusual, as it only occurred in the uridylylated state in vivo and thus lacked a deuridylylation response to nitrogen excess.

Safety, tolerability, and pharmacokinetics of single oral doses of BCH-10652 in healthy adult males

Racemic dOTC (BCH-10652) is a novel nucleoside reverse transcriptase inhibitor consisting of two enantiomers of 2'-deoxy-3'-oxa-4'-thiocytidine, (-)dOTC and (+)dOTC, that have both shown activity against human immunodeficiency virus type 1. The objectives of this study were to characterize the safety, tolerability, and stereospecific pharmacokinetics of single oral doses of racemic dOTC in healthy, nonsmoking adult male volunteers. Subjects received single oral doses of 100, 200, 400, 800, and 1,600 mg of racemic dOTC in a placebo-controlled, dose-rising, incomplete crossover study design, and the pharmacokinetics of both (+)dOTC and (-)dOTC were determined. At least six subjects were studied at each dose level, with each subject studied in three of five periods, receiving two different doses of racemic dOTC and one placebo dose. Plasma and urine drug concentrations were measured for 24 to 48 h after each dose. Pharmacokinetic models were fitted to the plasma concentrations of (+)dOTC and (-)dOTC using maximum likelihood and maximum a posteriori Bayesian procedures. Statistical hypothesis testing was by nonparametric analysis of variance (where possible) and, when tests with dose as a covariate were performed, by linear mixed-effects modeling. The mean terminal elimination half-lives for (+)dOTC and (-)dOTC were 15.3 h (coefficient of variation [CV], 28%) and 11.3 h (CV, 43%), respectively (P<0.05). The mean CV for total oral clearance (liter/h/65 kg) was 17.5 (25%) for (+)dOTC and 21.5 (24%) for (-)dOTC; for oral steady-state volume of distribution (liter/65 kg), values were 61.8 (24%) for (+)dOTC and 34.1 (33%) for (-)dOTC (P<0.05). The mean CV for renal clearance (liter/h/65 kg) of (+)dOTC was 10.4 (19%) and for (-)dOTC was 13.6 (20%) (P<0.05). There was no significant effect of dose size on the pharmacokinetics of racemic dOTC. All doses were well tolerated, and no serious adverse events or laboratory abnormalities were observed.

Absolute bioavailability and disposition of (-) and (+) 2'-deoxy- 3'-oxa-4'-thiocytidine (dOTC) following single intravenous and oral doses of racemic dOTC in humans

The purpose of this study was to characterize the pharmacokinetics and determine the absolute bioavailability of 2'-deoxy-3'-oxa-4'-thiocytidine (dOTC) (BCH-10652), a novel nucleoside analogue reverse transcriptase inhibitor, in humans. dOTC belongs to the 4'-thio heterosubstituted class of compounds and is a 1:1 mixture of its two enantiomers, (-) and (+) dOTC. Twelve healthy adult male volunteers each received oral (800-mg) and intravenous (100-mg) doses of dOTC in two study periods separated by at least 7 days. Sixteen plasma samples were obtained over 72 h and assayed for (-) and (+) dOTC, and the resultant data fit by candidate pharmacokinetic models. Data were weighted by the fitted inverse of the observation variance; model discrimination was by AIC. The pharmacokinetic model was a linear, three compartment model, with absorption occurring during one to three first-order input phases, each following a fitted lag time. The model goodness-of-fit was excellent; r(2) ranged from 0.995 to 1.0. The mean absolute bioavailabilities of (+) and (-) dOTC were 77.2% (coefficient of variation [given as a percentage] [CV%], 14) and 80.7% (CV%, 15), respectively. The median steady-state volume of distribution for (+) dOTC, 74.7 (CV%, 19.2) liters/65 kg, was greater than that for (-) dOTC, 51.7 (CV%, 16.7) liters/65 kg (P<0.05). The median total clearance of (+) dOTC was less than that of (-) dOTC, 11.7 (CV%, 17.3) versus 15.4 (CV%, 18.6) liters/h/65 kg, respectively (P< 0.05). The intersubject variability of these parameters was very low. The median terminal half-life of (+) dOTC was 18.0 (CV%, 31.5) h, significantly longer than the 6.8 (CV%, 69.9) h observed for (-) dOTC (P<0.01). No serious adverse events were reported during the study. These results suggest that dOTC is well absorbed, widely distributed, and well tolerated. The terminal half-lives indicate that dosing intervals of 12 to 24 h would be reasonable.

Relationship between energy deficits and body composition in elite female gymnasts and runners

PURPOSE

The purpose of this study was to evaluate energy balance and body composition in 42 gymnasts (mean age = 15.5 yr) and 20 runners (mean age = 26.6 yr), all of whom were on national teams or were nationally ranked.

METHODS

Athletes were assessed for body composition using DEXA and skinfolds, and energy balance was determined with a Computerized Time-Line Energy Analysis (CTLEA) procedure.

RESULTS

Results from the CTLEA were assessed as the number of within-day energy deficits (largest and frequency) and within-day energy surpluses (largest and frequency). There was a significant difference (P = 0.000) in the mean number of hourly energy deficits > 300 kcal experienced by gymnasts (9.45 +/- 6.00) and runners (3.70 +/- 5.34). There was also a significant difference (P = 0.001) in the mean number of hourly energy surpluses > 300 kcal experienced by gymnasts (1.40 +/- 3.04) and runners (6.20 +/- 5.50). The mean largest daily energy deficit was 743 (+/- 392) kcal for gymnasts and 435 (+/- 340) kcal for runners. The mean largest daily energy surplus was 239 (+/- 219) kcal for gymnasts, and 536 (+/- 340) kcal for runners. There was a significant relationship between the number of daily energy deficits > 300 kcal and DEXA-derived body fat percent for gymnasts (r = 0.508; P = 0.001) and for runners (r = 0.461; P = 0.041). There was also a negative relationship between the largest daily energy surplus and DEXA-derived body fat percentage for gymnasts (r = -0.418; P = 0.003). Using the energy balance variables, age, and athlete type (artistic gymnast, rhythmic gymnast, middle-distance runner, long-distance runner) as independent variables in a forward stepwise regression analysis, a small but significant amount of variance was explained in DEXA-derived (P = 0.000; R2 = 0.309) and skinfold-derived (P = 0.000; R2 = 0.298) body fat percent by the number of energy deficits > 300 kcal and age.

CONCLUSIONS

These data suggest that within-day energy deficits (measured by frequency and/or magnitude of deficit) are associated with higher body fat percentage in both anaerobic and aerobic elite athletes, possibly from an adaptive reduction in the REE. These data should discourage athletes from following restrained or delayed eating patterns to achieve a desired body composition.

The development and pharmacological characterization of calcium channel currents in cultured embryonic rat septal cells

We characterized the development and pharmacology of Ca(2+) channel currents in NGF-treated embryonic day 21 cultured rat septal cells. Using standard whole-cell voltage clamp techniques, cells were held at -80 mV and depolarized to construct current-voltage relations in conditions that eliminated Na(+) or K(+) currents. Barium (10 mM) was used as the charge carrier. Maximum current was produced when cells were depolarized to 0 or +10 mV. Recordings from 77 cells revealed that Ca(2+) channel current density increases over time in culture from nearly 0 pA/pF on day 2 in vitro (0.65+/-0.65 pA/pF) to (6.95+/-1.59 pA/pF) on days 6-8. This was followed by a period where currents became nearly 3 times more dense (21.05+/-7.16 pA/pF) at days 9-17. There was little or no evidence for low voltage activated currents. Bath application of 50-100 microM CdCl(2) abolished approximately 95% of the current. Application of 10 microM nimodipine produced a 50.5+/-3.22% reduction in current, 2 microM omega-CTx-GVIA produced a 32.4+/-7.3% reduction, and application of 4 microM omega-Aga-IVA produced a 29.5+/-5.73% reduction in current. When all three inhibitors (10 microM nimodipine, 2 microM omega-CTx-GVIA, and 4 microM omega-Aga-IVA) were applied simultaneously, a residual current remained that was 18.0+/-4.9% of the total current and was completely abolished by application of CdCl(2). This is the first report to characterize Ca(2+) channel currents in cultured embryonic septal cells. These data indicate that there is a steady increase in Ca(2+) channel expression over time in vitro, and show that like other cultured neuronal cells, septal cells express multiple Ca(2+) channel types including L, N, P/Q and R-type channels.

A biomechanical comparison of screw and wire fixation with and without polymethylmethacrylate re-enforcement for acetabular osteotomy stabilization in dogs

OBJECTIVE

Compare the biomechanical characteristics of screw and wire fixation with and without polymethylmethacrylate (PMMA) re-enforcement for acetabular osteotomy stabilization in dogs.

ANIMALS

Pelves removed from 8 adult mixed breed dogs weighing between 25 and 30 kg.

PROCEDURE

The pubic symphysis of each pelvis was split and a central transverse acetabular osteotomy was performed. One hemipelvis from each dog was stabilized with the composite fixation (interfragmentary Kirschner wire, two screws and a figure-of-eight orthopedic wire with PMMA). The contralateral hemipelves was stabilized with an interfragmentary Kirschner wire, two screws, and a figure-of-eight orthopedic wire without PMMA. All hemipelves were tested in bending by using a materials testing machine at a cross head speed of 5 mm/min. An extensometer was placed on the dorsomedial surface of the hemipelves centered over acetabular osteotomy to record distraction of the osteotomy during loading. A load/deformation curve and a load/distraction curve was produced for each hemipelvis. The slope for the initial linear portion of the load/deformation curve and the load/distraction curve, yield load and maximum load sustained were compared between repair groups using a paired t-test with P < .05 considered significant.

RESULTS

The slope of the load/deformation curve was significantly greater (P = .001) for hemipelves stabilized with the composite fixation (mean +/- SD: 69 +/- 18 N/mm) compared with hemipelves stabilized without PMMA (mean +/- SD: 39 +/- 8 N/mm). There was no significant difference (P = .593) between repair groups in the slope of the load/distraction curves as measured on the extensometer. Yield load was significantly greater (P = .0002) for hemipelves stabilized with the composite fixation (mean +/- SD: 184 +/- 25 N) compared to hemipelves stabilized without PMMA (mean +/- SD: 74 +/- 12 N). Maximum load sustained was also significantly greater (P = .013) for hemipelves stabilized with the composite fixation (mean +/- SD: 396 +/- 71 N) compared to hemipelves stabilized without PMMA (mean +/- SD: 265 +/- 94 N). Failure of hemipelves stabilized with the composite fixation occurred primarily by ventrolateral bending of the cranial and caudal pelvic segments at the osteotomy site. Failure of hemipelves stabilized without PMMA occurred by ventrolateral bending of the cranial and caudal pelvic segments at the osteotomy site with pronounced concurrent ventrolateral rotation of the cranial pelvic segment.

CONCLUSION

PMMA improves the mechanical characteristics of acetabular fracture fixation, at least in part by neutralization of rotational forces. The results of this study justify use of PMMA as a component of the composite fixation when repairing acetabular fractures.

Morning spot and 24-hour urinary 6 beta-hydroxycortisol to cortisol ratios: intraindividual variability and correlation under basal conditions and conditions of CYP 3A4 induction

A single spot urine collection to measure the ratio of 6 beta-hydroxycortisol (6 beta-OHC) to free cortisol (C) has been proposed as a research tool for the assessment of CYP3A4 induction. However, intraindividual variability in 6 beta-OHC/C under basal conditions and conditions of induction has not been prospectively evaluated, and findings on the correlation between morning spot and 24-hour urinary ratios have been conflicting. In this study, the variability in morning spot and 24-hour urinary 6 beta-OHC/C ratios was assessed in 15 healthy adult male volunteers before, during, and after oral administration of rifampin 600 mg once daily for 14 days. In addition, the correlation between morning spot and 24-hour urinary ratios measured under baseline, maximum induction, and postinduction was determined. Intraindividual coefficients of variation (CVs) at baseline for the morning spot and 24-hour ratios were 54.3% and 57.1%, respectively, and were not changed significantly during induction. No significant differences were detected in the variability between the morning spot and 24-hour ratios at baseline, maximum induction, or postinduction. A good correlation (r = 0.61, p < 0.0001) was detected between the mean morning spot and 24-hour urinary ratios. Mean (+/- SEM) percent increases in the morning spot and 24-hour ratios at maximum induction relative to baseline were 320% +/- 73% and 137% +/- 30%, respectively (p = 0.019). All 15 subjects had an increase in the mean morning spot ratio at maximum induction relative to baseline, whereas 12 subjects showed an increase in the mean 24-hour ratio. The time course of changes in the mean morning spot urinary ratio in response to a 14-day course of rifampin was also similar to that reported previously in a study using 24-hour urine collections. These findings suggest that measurement of the morning spot urinary 6 beta-OHC/C ratio is an effective and efficient method for evaluating the potential of investigational agents to induce CYP3A4.

Pharmacokinetics and protein binding of eprosartan in hemodialysis-dependent patients with end-stage renal disease

STUDY OBJECTIVES

To compare eprosartan pharmacokinetics in hemodialysis patients and in volunteers with normal renal function, and to determine the effect of hemodialysis on these values.

DESIGN

Open-label, parallel-group, single-dose study.

SETTING

Outpatient hemodialysis treatment center and an industry-affiliated clinical pharmacology unit.

PATIENTS

Ten healthy volunteers and nine hemodialysis patients.

INTERVENTION

A single oral dose of eprosartan 400 mg was administered to volunteers on 1 day and to patients on 2 days (a nondialysis and a dialysis day). Patients underwent high-flux hemodialysis.

MEASUREMENTS AND MAIN RESULTS

Concentrations of eprosartan in plasma and dialysate were assayed by high-performance liquid chromatography; plasma protein binding was determined by ultrafiltration. Eprosartan pharmacokinetics showed greater variability in patients than in volunteers. However, six of nine patients had exposures that were within the range observed for volunteers. Mean total AUC(0-t) was increased approximately 60% (95% CI-22, 225) in patients. Total Cmax was similar between groups (PE = 1.01, 95% CI -40, 71). Mean percent fraction unbound (%f(u)) in patients (3.02%) was significantly greater than that in volunteers (1.74%). Unbound AUC(0-t) and unbound Cmax were, on average, approximately 172% (95% CI 28, 479) and 73% (95% CI -1, 199) greater, respectively, in patients. After hemodialysis, the mean %f(u) decreased from 3.19-2.01%. Mean recovery of eprosartan in dialysate was 6.8 mg (range 0-23.1 mg) and hemodialytic clearance was approximately 11 ml/minute, which does not represent a significant portion of total clearance.

CONCLUSIONS

Eprosartan was safe and well tolerated in both groups. Based on its known safety profile and because of its exaggerated pharmacokinetic variability in patients undergoing hemodialysis, treatment should be individualized based on tolerability and response. Supplemental doses of eprosartan after hemodialysis are unnecessary.

Effect of age and gender on the pharmacokinetics of eprosartan

AIMS

To compare the pharmacokinetics of eprosartan between young (18-45 years) and elderly (65 years) men and between young men and young, premenopausal women (18-45 years).

METHODS

Twenty-four subjects (eight subjects/group) received a single 200 mg eprosartan oral dose followed by serial blood sampling over 24 h.

RESULTS

Eprosartan was safe and well tolerated. There were no apparent differences in the pharmacokinetics of eprosartan between young females and young males or in the plasma protein binding of eprosartan (98%) for the three groups. On average, AUC (0,infinity) and Cmax values were approximately 2-fold higher in elderly men than young men [AUC (0,infinity) 95% CI: 1.22, 4.34; Cmax 95% CI: 0.98, 4.001. Similarly, unbound AUC (0,infinity) and Cmax values were, on average, approximately 2-fold higher in elderly men than young men [unbound AUC (0,infinity) 95% CI: 1.29, 4.44; unbound Cmax 95% CI: 1.02, 4.12]. tmax was delayed in the elderly men compared with young men, with a median difference of 2.5 h (95% CI: 1.00, 3.01 h).

CONCLUSIONS

No gender differences were observed in the pharmacokinetics of eprosartan. There were approximately two fold higher AUC and Cmax values for eprosartan observed in elderly men as compared with young men, most likely due to increased bioavailability of eprosartan in the elderly. Based on the excellent safety profile in the elderly in Phase III clinical trials (doses up to 1200 mg eprosartan) eprosartan can be safely administered to elderly hypertensive patients without an initial dose adjustment. Subsequently, the dose of eprosartan, as for other antihypertensive agents, may be individualized based on tolerability/response.

Listener ratings of the intelligibility of tracheoesophageal speech in noise

The purpose of this investigation was to determine the extent to which listener ratings of the intelligibility of tracheoesophageal puncture (TEP) speech vary as a function of different signal-to-noise ratios. Fifty college students, 25 men and 25 women (Median age = 19.7 years) participated in the study. They were instructed to assign numbers to audio-recorded speech samples in each of nine signal-to-noise ratio conditions (+65 dB, +20 dB, +15 dB, +10 dB, +5 dB, 0 dB, -5 dB, -10 dB, and -15 dB) in two separate magnitude estimation scaling tasks. During Task 1 the subjects rated the intelligibility of a TEP speech sample. In Task 2 the subjects rated the intelligibility of a normal speech sample. The results indicated that as the levels of background noise increased, listener ratings of intelligibility decreased (F 8,392 = 37.84; p < or = .0001).

Eprosartan does not affect the pharmacodynamics of warfarin

Eprosartan is an angiotensin II receptor antagonist being developed for the treatment of hypertension and heart failure. The effect of eprosartan on the steady-state anticoagulant activity of warfarin was evaluated in 18 healthy male volunteers. Each subject's daily warfarin dose was titrated over 9 days to achieve a stable international normalized ratio (INR) of 1.3 to 1.6 by day 14. After the 14-day warfarin titration phase, subjects were randomized to receive either eprosartan 300 mg or matching placebo twice a day for 7 days. All subjects continued to take the warfarin dose established during the 14-day titration phase. The anticoagulant activity of warfarin was statistically equivalent when coadministered with eprosartan or with placebo. No serious or unexpected adverse events suggestive of abnormal bleeding occurred during coadministration of eprosartan and warfarin. As measured by the INR, there is no apparent effect of eprosartan on the anticoagulant effect of warfarin.

Urinary excretion of 6 beta-hydroxycortisol as an in vivo marker for CYP3A induction: applications and recommendations

OBJECTIVE

To evaluate the usefulness of 6 beta-hydroxycortisol as a screen for CYP3A induction in early-phase drug development.

METHODS

Five groups of 12 healthy elderly men were randomized to one of five treatment regimens: (1) 600 mg rifampin (INN, rifampicin) once daily, (2) placebo once daily, (3) 40 mg SB 216469 twice a day, (4) 60 mg SB 216469 twice a day, or (5) 40 mg SB 216469 three times a day. All medications were taken orally and administered for 7 consecutive days. Urine was collected over a 24-hour period for each subject before administration and on the last day of administration for each respective regimen for measurement of 6 beta-hydroxycortisol and 17-hydroxycorticosteroid concentrations.

RESULTS

Subjects in the rifampin group had a significant increase from predose value in the 24-hour urinary excretion of 6 beta-hydroxycortisol and the ratio of 6 beta-hydroxycortisol to 17-hydroxycorticosteroid. All 12 subjects in the rifampin group had increases in 6 beta-hydroxycortisol excretion, whereas 11 of 12 had an increase in the ratio. The placebo and three active treatment groups did not show significant changes in either parameter.

CONCLUSIONS

Urinary excretion of 6 beta-hydroxycortisol may be useful as a screening tool in early-phase development to assess the potential for an investigational drug to induce CYP3A.

Effects of a functional knee brace for ACL insufficiency during treadmill running

PURPOSE

To assess the effects of a functional knee brace (FKB) for anterior cruciate ligament insufficiency (ACLI) on physiological and perceptual parameters during treadmill running.

METHODS

Thirteen ACLI subjects (time since injury, 5.8 +/- 5.3 yr), performed an incremental test to exhaustion and two constant load 20-min tests, one at an intensity below lactate threshold (bLT), and the other at an intensity above LT (aLT) each with and without their FKB.

RESULTS

Bracing had no effect on peak variables except for higher ratings of perceived exertion at the legs (RPE-L) at the velocities associated with a blood lactate concentration [HLa] of 4.0 mM and at peak. Bracing had no effect when exercising at bLT but did significantly alter the metabolic profile developed during the performance of the aLT tests (83 +/- 0.03% VO2peak). In particular, FKB resulted in elevated blood [HLa] (23%), VO2 (4%), VE (12%), VCO2 [corrected] (7%), and VE/VO2 (7%). HR and slow component VO2 did not differ between the brace and no brace aLT tests. RPE-L and RPE-knee were significantly elevated during aLT when the brace was worn. Suspected mechanisms include alterations in muscle recruitment patterns and/or occlusion.

CONCLUSIONS

When ACLI individuals wear a FKB during high intensity straight-ahead running exercise of long duration, physiological parameters are affected.

Urine drug screening results from volunteers in phase I clinical pharmacology studies: are we being misled?

The general intent of phase I clinical pharmacology studies is to demonstrate the safety and tolerability of investigational new drugs in healthy human volunteers. There is emerging evidence that people who volunteer for these studies are not always truthful with investigators during the screening process. All healthy volunteers who participate in studies at the SmithKline Beecham Clinical Pharmacology Unit in Philadelphia, Pennsylvania, are required to submit to urine drug testing. During 11 months of 1996, a total of 1,469 urine samples were collected and tested for eight different drugs or classes of drugs of abuse. The urine samples collected during the first five months of 1996 were all analyzed using EMIT (Syva Corporation) and interpreted according to the guidelines established by the National Institutes of Drug Abuse (NIDA). Of 534 samples, 12 (2.2%) were reported as positive. During the last 6 months of 1996, a new methodology using a fluorescence polarization immunoassay (FPIA) was used. This assay had lower limits of quantification than EMIT, and more stringent interpretation guidelines than those of the NIDA were used. Of 935 samples analyzed by FPIA, 89 (9.5%) were positive. Of the 89 positive test results, 59 were below the cut-offs specified by the NIDA guidelines and would have been reported as negative. Interpretation of urine drug screen results according to the NIDA guidelines is not acceptable for clinical pharmacology investigations.

The effects of eprosartan, an angiotensin II AT1 receptor antagonist, on uric acid excretion in patients with mild to moderate essential hypertension

The effects of antihypertensive agents, including angiotensin II receptor antagonists, on urine uric acid excretion may have important clinical consequences. Therefore, the effects of single and repeated doses of eprosartan on uric acid excretion were evaluated in 57 male patients with mild-to-moderate essential hypertension in a double-blind, randomized, placebo-controlled, repeated dose, dose-rising, two-period, period-balanced, crossover study conducted in two parts. In part 1 (n = 33), the effects of eprosartan dose regimens of 50 mg, 100 mg, and 350 mg once daily and 150 mg every 12 hours on uric acid excretion were assessed. In part 2 (n = 24), the effects of eprosartan dose regimens of 600 mg, 800 mg, and 1,200 mg once daily on uric acid excretion were assessed. Eprosartan was well tolerated. There were no appreciable changes from predose values in fractional excretion of uric acid (FEua), urine uric acid excretion, urine uric acid to creatinine (Uua/Ucr) ratios, or serum uric acid concentrations after single or repeated doses of eprosartan. Mean Uua/Ucr ratios for eprosartan doses of 50 mg, 100 mg, or 350 mg daily or 150 mg every 12 hours were comparable to those for placebo. Mean FEua values and Uua/Ucr ratios for eprosartan doses of 600 mg, 800 mg, or 1,200 mg daily also were comparable to those for placebo. Single and repeated oral doses of eprosartan ranging from 50 mg to 1,200 mg daily had no effect on serum uric acid concentrations or urine uric acid excretion in patients with mild-to-moderate essential hypertension.

SK&F107647: a synthetic hematoregulatory peptide in patients with solid tumor malignancies: a phase I trial

SK&F107647 is a synthetic hematoregulatory peptide (HP) increases both the number and function of progenitor cells, enabling improved survival after lethal myelosuppression, lethal fungal infection, and lethal herpes simplex virus infection in murine models. This Phase I single-blind placebo-controlled dose-rising crossover trial examined the efficacy of SK&F107647 in patients who had incurable solid tumor malignancies. Sixteen patients were treated. Six adverse events in 3 patients were considered to be possibly related to SK& F107647; all were mild to moderate in nature (mild nervousness and agitation at 0.01 ng/kg, moderate fever and mild nausea at 0.1 ng/kg, elevated hepatic enzymes at 0.1 ng/kg, and mild vomiting at 1.0 ng/kg). Plasma half-life was 2.44 hours (+/-1.07 standard deviation). The observed area volume of distribution was 16.7 L (+/-7.7 standard deviation) and clearance was 5.04 L/hour (+/-1.83 standard deviation). When administered as a single 2-hour intravenous infusion at doses ranging from 0.01 to 100 ng/kg, SK&F107647 is safe and well tolerated.

A dose-response study to assess the renal hemodynamic, vascular, and hormonal effects of eprosartan, an angiotensin II AT1-receptor antagonist, in sodium-replete healthy men

STUDY DESIGN

The effects of orally administered eprosartan on changes induced by angiotensin II in blood pressure, renal hemodynamics, and aldosterone secretion were evaluated in healthy men in this double-blind, randomized, single-dose, placebo-controlled crossover study, which was conducted in three parts. Part 1 (n = 12) assessed the onset and duration of the effect of eprosartan 350 mg or placebo; part 2 (n = 14) assessed the dose-response profile of placebo or 10, 30, 50, 70, 100 or 200 mg eprosartan; and part 3 (n = 5) assessed the duration of the effect of 50, 100, or 350 mg eprosartan.

RESULTS

In part 1 of the study; 350 mg eprosartan caused complete inhibition of angiotensin II-induced pressor and renal blood flow hemodynamic effects (effects on effective renal plasma flow [ERPF]) and inhibited angiotensin II-induced stimulation of aldosterone secretion from 1 to 3 hours after administration. Eprosartan, 350 mg, inhibited the effects of exogenous angiotensin II by approximately 50% to 70% from 12 to 15 hours after dosing. Eprosartan had no angiotensin II agonistic activity and produced an increase in ERPF starting at 1 to 4 hours after dosing. In study part 2, at 3 hours after single doses of 10, 30, 50, 70, 100, and 200 mg, eprosartan inhibited angiotensin 11-induced decreases in ERPF by 39.1%, 49.9%, 33.0%, 56.0%, 71.0%, and 85.7%, respectively, compared with placebo. In study part 3, 50, 100, and 350 mg eprosartan produced measurable Inhibition of angiotensin II-induced decreases in ERPF from 12 to 15 hours after administration. In parts 2 and 3, the eprosartan angiotensin II antagonism on blood pressure response and aldosterone secretion mirrored the angiotensin II antagonism on ERPF.

Effect of ranitidine on the pharmacokinetics of orally administered eprosartan, an angiotensin II antagonist, in healthy male volunteers

OBJECTIVE

To assess the effect of ranitidine on the pharmacokinetics of eprosartan in healthy male volunteers.

DESIGN

Single-center, randomized, open-label, two-period, period-balanced, crossover study.

PATIENTS

Seventeen healthy men aged 19 to 43 years.

INTERVENTION

In each period (separated by a > or = 7 d washout), subjects received a single 400-mg oral dose of eprosartan alone, or a single oral dose of eprosartan 400 mg and ranitidine 150 mg on day 4 after 3 days of ranitidine 150 mg twice daily. Serial pharmacokinetic samples were obtained for up to 24 hours following eprosartan dosing.

MAIN OUTCOME MEASURES

Plasma and urine eprosartan concentrations during each treatment session.

RESULTS

Eprosartan maximum concentration (Cmax), the AUC from time-zero to the last quantifiable concentration (AUC0-t), and renal clearance (Cl(r)) values were approximately 7%, 11%, and 4% lower, respectively, when administered with ranitidine compared with eprosartan alone. The 95% CIs for the ratio of eprosartan plus ranitidine compared with eprosartan alone were 0.81 to 1.07, 0.77 to 1.03, and 0.64 to 1.43, for Cmax, AUC0-t, and Cl(r), respectively, indicating no statistically significant difference between regimens.

CONCLUSIONS

Repeated doses of ranitidine did not have a marked effect on the single-dose pharmacokinetics of eprosartan.

Pharmacokinetics and protein binding of eprosartan in healthy volunteers and in patients with varying degrees of renal impairment

This was an open-label, parallel group study to compare the pharmacokinetics of multiple oral doses of eprosartan in subjects with normal renal function (Clcr > 80 mL/min; n = 8) and patients with mild (Clcr 60-80 mL/min; n = 8), moderate (Clcr 30-59 mL/min; n = 15), or severe (Clcr < 30 mL/min; n = 3) renal insufficiency. Each subject received oral eprosartan 200 mg twice daily for 6 days and a single dose on day 7. Mean total maximum concentration (Cmax) and area under the concentration-time curve from 0 to 12 hours (AUC0-12) were similar for healthy subjects and those with mild renal impairment, but were an average of 25% to 35% and 51% to 55% greater for patients with moderate and severe renal impairment, respectively, compared with healthy subjects. Mean renal clearance (Clr), which was similar for healthy subjects and patients with mild renal impairment, was decreased an average of 41% and 95% in the groups with moderate and severe renal impairment, respectively, compared with normal subjects. Eprosartan was highly bound to plasma proteins in all groups; however, the unbound fraction was increased approximately two-fold in the group with severe renal impairment. Mean unbound Cmax and AUC0-12 were an average of 53% to 61% and 185% to 210% greater for the patients with moderate and severe renal impairment, respectively, compared with healthy subjects. Headache was the most common adverse experience reported in all subgroups. Eprosartan was safe and well tolerated regardless of degree of renal impairment. Cmax and AUC were increased and renal clearance decreased in patients with moderate to severe renal impairment in comparison to healthy subjects and patients with mild renal impairment. However, based on the moderate renal clearance and known safety profile of eprosartan, it is not necessary to adjust the dose of eprosartan in patients with renal insufficiency.

A dose proportionality study of eprosartan in healthy male volunteers

The present study investigated the proportionality of exposure after single oral doses of 100, 200, 400, and 800 mg of eprosartan, a nonpeptide, nonbiphenyl angiotensin II receptor antagonist, in 23 healthy young men. Eprosartan was safe and well tolerated. Exposure to eprosartan increased with dose but in a less than proportional manner. For each two-fold dose increase, area under the concentration--time curve (AUC) increased an average of 1.6 to 1.8 times and maximum plasma drug concentration (Cmax) increased an average of 1.5 to 1.8 times. For both parameters, the greatest difference from the dose multiple was observed between the 400- and 800-mg doses. Dose proportionality of eprosartan, as assessed by an equivalence-type approach using the 100-mg dose as the reference and a 30% acceptance region (0.70, 1.43), was achieved for the 200- and 400-mg doses for AUC and the 200-mg dose for Cmax. The observed changes in the pharmacokinetics of eprosartan suggest slight saturation of absorption of eprosartan over the 100- to 800-mg dose range, most likely due to the physicochemical properties of the drug (pH-dependent aqueous solubility and lipophilicity).

Paroxetine does not affect the cardiac safety and pharmacokinetics of terfenadine in healthy adult men

Potent CYP3A4 inhibitors such as ketoconazole can cause dangerous increases in plasma concentrations of the H-1 antagonist terfenadine. In light of recent reports that the selective serotonin reuptake inhibitor antidepressants may be weak CYP3A4 inhibitors, this study was designed to investigate the effects of paroxetine on the pharmacodynamic and pharmacokinetic profile of terfenadine. Twelve healthy male volunteers participated in a randomized open-label, two-period, steady-state crossover study. Terfenadine (60 mg twice daily for 8 days) was administered alone and with paroxetine at steady state (20 mg once daily for 15 days, with terfenadine on days 8 through 15). Extensive electrocardiogram monitoring was conducted throughout, and terfenadine and carboxyterfenadine pharmacokinetics were assessed at the end of each treatment period. One subject withdrew because of adverse experiences related to paroxetine, but the other 11 subjects completed the study uneventfully. On the final day of coadministration, the rate-corrected QT interval (QTc) was unaltered compared with terfenadine dosed alone; maximum QTc values (mean [SEM]) were 404 (4) and 405 (5) msec, respectively. Terfenadine pharmacokinetics were also unchanged; geometric mean steady-state area under the curve (AUC)tau values were 30.0 ng.hr/mL during coadministration compared with 30.8 ng.hr/mL when dosed alone (p > 0.05). The corresponding Cmax values were 3.68 and 3.64 ng/mL (p > 0.05). There was, however, a small (on average 17-20%), unexplained reduction in the steadystate Cmax and AUCtau of carboxyterfenadine during coadministration with paroxetine. In conclusion, paroxetine does not affect the pharmacokinetics or cardiovascular effects of terfenadine. The small reduction in carboxyterfenadine plasma concentrations is unlikely to be important clinically.

Relevance of oral intake and necessity to void as ambulatory surgical discharge criteria

Discharge criteria used in the outpatient setting of a 500-bed academic medical center were evaluated by nursing staff in two ambulatory units to determine validity in identifying patient readiness for discharge. Criteria categories include temperature, circulation, activity and mental status, pain, bleeding, voiding, and oral intake. The hospital course and post-discharge course of a convenience sample of 248 ambulatory subjects was drawn from consecutive patients. Post-discharge recovery outcomes identified by the telephone assessment included recovery, complications, necessity of further medical treatment, and the need to return to a medical facility. The descriptive results showed the safety of the seven discharge criteria. Voiding and oral intake were related to prolonged stays in the ambulatory units. Approval was granted by the Hospital Policy Board to relax discharge criteria, and make voiding and oral intake optional for patients. A stage II follow-up study of 1,582 patient subjects was conducted using the new criteria of voluntary voiding and oral intake. The average ambulatory stay was reduced 50 minutes after voiding and oral intake were made optional.

Effect of fluconazole on the pharmacokinetics of eprosartan and losartan in healthy male volunteers

OBJECTIVE

To investigate the effect of steady-state fluconazole administration on the disposition of eprosartan, losartan, and E-3174.

METHODS

Sixteen healthy male subjects received 300 mg eprosartan every 12 hours, and 16 received 100 mg losartan every 24 hours on study days 1 to 20. All 32 subjects received 200 mg fluconazole every 24 hours beginning on day 11 and continuing through day 20. Serial blood samples were collected over one dosing interval on study days 10 and 20 for measurement of plasma concentrations of eprosartan, losartan, and E-3174 (the active metabolite of losartan).

RESULTS

There was no significant difference in eprosartan area under the concentration-time curve from time 0 to time of last quantifiable concentration [AUC(0-t)] or maximum concentration (Cmax) when administered alone and with fluconazole. After concomitant administration with fluconazole, losartan AUC(0-t) and Cmax were significantly increased 66% and 30%, respectively, compared with those values for losartan alone. The AUC(0-t) and Cmax for E-3174 were significantly decreased 43% and 56%, respectively, after administration of losartan with fluconazole.

CONCLUSIONS

Fluconazole significantly increases the steady-state AUC of losartan and inhibits the formation of the active metabolite of losartan, E-3174. In contrast, fluconazole administration has no effect on the steady-state pharmacokinetics of eprosartan.

Lack of effect of eprosartan on the single dose pharmacokinetics of orally administered digoxin in healthy male volunteers

AIMS

To study the effect of eprosartan, a nonbiphenyl tetrazole angiotensin II receptor antagonist, on digoxin pharmacokinetics in a randomized, open-label, two period, period balanced crossover study in 12 healthy men.

METHODS

Each subject received a single 0.6 mg oral dose of digoxin (Lanoxicaps 0.2 mg/capsule, Glaxo Wellcome) alone or following 4 days of dosing with eprosartan 200 mg orally every 12 h. Each study period was separated by a 14 day washout interval. Serial blood samples were obtained for up to 96 h after each digoxin dose for determination of digoxin pharmacokinetics. The effect of eprosartan on digoxin pharmacokinetics was assessed through an equivalence-type approach using AUC(0, t') as the primary endpoint.

RESULTS

For AUC(0, t'), the ratio of digoxin+eprosartan: digoxin alone was 0.99 with a 90% confidence interval (CI) of [0.90, 1.09]. For Cmax, the ratio was 1.00 with a 90% CI of [0.86, 1.17]. tmax was similar for both regimens. Both regimens were safe and well tolerated.

CONCLUSIONS

Based on AUC and Cmax data, it can be concluded that eprosartan has no effect on the pharmacokinetics of a single oral dose of digoxin.

Eprosartan, an angiotensin II receptor antagonist, does not affect the pharmacodynamics of glyburide in patients with type II diabetes mellitus

The potential for eprosartan, a nonbiphenyl tetrazole angiotensin II receptor antagonist, to affect the 24-hour plasma glucose profiles in type II diabetic patients treated with glyburide was investigated in this randomized, placebo-controlled, double-blind (eprosartan-placebo phase only), two-period, period-balanced, crossover study. All patients received a stable oral dose (3.75-10 mg/day) of glyburide for at least 30 days before the first dose of double-blind study medication was administered. Patients were randomized to receive either 200-mg oral doses of eprosartan twice daily or matching oral placebo doses concomitantly with glyburide for 7 days during each treatment period. After a minimum washout period of 14 days, patients were crossed over to the alternate treatment. Serial samples to measure glucose concentrations in plasma were collected over a 24-hour period on the day before administration of eprosartan or placebo and again on day 7. Mean glucose concentrations were comparable between treatment groups before administration of eprosartan or placebo. The point estimate (90% confidence interval) for the ratio of the average mean 24-hour plasma glucose concentrations of eprosartan + glyburide to placebo + glyburide after 7 days of administration was 0.96 (0.90, 1.01). Eprosartan did not significantly alter the 24-hour plasma glucose profile in patients with type II diabetes mellitus who were previously stabilized on glyburide.

Role of hyperpronation as a possible risk factor for anterior cruciate ligament injuries

OBJECTIVE

The purpose of this study was to examine the relationship between hyperpronation and the occurrence of noncontact injury to the anterior cruciate ligament (ACL).

DESIGN AND SETTING

Subjects were categorized as either ACL injured (ACLI) or ACL uninjured (ACLU). All ACLI subjects received their injuries from a noncontact mechanism. To justify using the ACLI subjects' uninjured legs as representative of their preinjury state, a t test was used to compare the differences between the left and right foot for the ACLU group on both measurements. Based on the results of the t test, a regression analysis was performed to determine whether group membership could be predicted from navicular drop. All measures were performed in a university athletic training room.

SUBJECTS

Fourteen ACLI subjects (age = 21.07 +/- 0.83 yr, ht = 174.81+/-8.29 cm, wt = 72.32+/-13.47 kg) and 14 ACLU subjects (age = 21.14+/-2.03 yr, ht = 177.35+/-11.31 cm, wt = 72.99+/-14.81 kg) participated.

MEASUREMENTS

Hyperpronation was assessed via the navicular drop test and the calcaneal stance test.

RESULTS

No significant difference (p > .05) between feet for the navicular drop test was found. However, there was a significant difference (p < .05) between feet for the calcaneal stance test, and, thus, this measure was not used in the regression analysis. Using the navicular drop score, the regression analysis was unable to predict group membership.

CONCLUSIONS

Hyperpronation as measured by the navicular drop test was not a predictor of ACL injury, and, thus, may not be a predisposing factor to noncontact ACL injuries.

Callus distraction in reconstructive foot surgery

Though by no means a new concept, the science of callus distraction has stimulated significant interest among surgeons over the past several years. As our knowledge and understanding of the principles of this technique have evolved, the clinical indications have been expanded. In this manuscript, we will illustrate several examples of these broadened indications. An innovative alternative to the Evans opening wedge calcaneal osteotomy, which usually requires bone graft or bone graft substitutes, is presented.

Retrospective evaluation of graded stress examination of the ankle

Stress radiography of the ankle commonly is used to evaluate talar tilt in patients with a history of inversion ankle sprains. Manual and instrumented procedures have been variously described in the literature. No reports have documented normative talar tilt as measured using the Telos ankle stress device in a large clinical population. In addition, little has been done to examine the value of using graded displacement forces compared with a single displacement force. Bilateral Telos examinations from 113 consecutive patients taken during a 4-year period were evaluated for this study. No measurable talar tilt was observed in 65.8% of the ankles in this study. Talar tilt ranged from 1.7 degrees to 24.9 degrees in injured ankles. In patients with quantifiable talar tilt, all had greater talar tilt at the 15 kPa force than at all other forces. Because of the variability in talar tilt in injured and comparison ankles, clinical conclusions regarding injury severity cannot be made on measured talar tilt alone. The analysis suggests that inversion stress examination is helpful in documenting gross talar instability, but the discriminant value of the procedure to determine the anatomy and severity of lateral ligament injury is tenuous.

Hot and cold whirlpool treatments and knee joint laxity

OBJECTIVE

To examine the influence of clinical applications of heat and cold on arthrometric laxity measurements of the knee.

DESIGN AND SETTING

The knee joint was submersed 4 inches above the patella in hot and cold whirlpools containing water of 40 degrees C and 15 degrees C for 20 minutes. A control was also performed to provide a neutral temperature comparison group.

SUBJECTS

Eight males and 7 females with no history of knee injury.

MEASUREMENTS

The knee was maintained at 20 degrees flexion and tibial rotation at either 15 degrees of internal rotation, 15 degrees of external rotation, or a neutral measurement with a modified KT-1000 knee arthrometer equipped with an LCCB-50 strain gauge that allowed for the digital display of the applied distraction forces. Order of testing was counterbalanced. Subjects underwent each condition once, with each trial on separate days. Two 2-factor repeated measure analyses of variance were performed to test effects of temperature on knee laxity for the dependent measure (laxity at 89N and at maximal displacement forces).

RESULTS

There was no thermal effect on displacement at 89N nor at maximal distraction (p > .05). A difference was found with respect to test position, with external rotation showing a greater displacement than internal rotation (p < .05).

CONCLUSIONS

There was no evidence that hot or cold whirlpool treatments alter knee laxity as assessed with the KT-1000. Rotation of the tibia does affect the magnitude of displacement of the knee. Further research is needed to determine if these findings can be applied to ACL-deficient or ACL-reconstructed knees.

Alternatives to the closing base wedge osteotomy

The closing base wedge osteotomy remains a viable option in treating hallux valgus deformities with high intermetatarsal angles; however, the procedure can be technically difficult to perform and has been associated with a fair number of potential complications. As a result, a variety of osteotomies have been introduced and modified over the years that may serve as alternatives. Though all procedures possess complications, several of these alternatives do offer some significant advantages over the closing base wedge osteotomy.

Interspecies pharmacokinetics of a novel hematoregulatory peptide (SK&F 107647) in rats, dogs, and oncologic patients

PURPOSE

To study the pharmacokinetics of SK&F 107647, a novel hematoregulatory agent, in rats, dogs, and patients with non-lymphoid solid tumor malignancy.

METHODS

Sprague Dawley rats and beagle dogs (n = 6 each; 3 M, 3 F) were given 25 mg/kg of SK&F 107467 as an iv bolus injection, and patients (n = 6; 4 M, 2 F) received 100 mg/kg as a 2 hour iv infusion. Plasma samples were assayed for drug using either HPLC (rat and dog) or RIA (human).

RESULTS

In each species the plasma clearance (CL) of SK&F 107647 was low in relation to hepatic blood flow, and the volume of distribution (Vd ss) was reflective of distribution to extracellular body water. The plasma CL in humans was near that of average glomerular filtration rate. Using allometric equations for interspecies scaling (Y = a.W(b)), body-weight normalized human pharmacokinetic data were reasonably predicted using either the body weight normalized rat or the dog data. The allometric exponents (b) for CL, Vd(ss), and T(1/2) of SK&F 107647 were 0.63, 0.94, and 0.29, respectively.

CONCLUSIONS

Use of a limited pool of available animal data allowed for reasonable predictions of human pharmacokinetics of SK&F 107647.

Effects of ofloxacin on the pharmacokinetics and pharmacodynamics of procainamide

Procainamide is a class I antiarrhythmic agent that undergoes active tubular secretion through the organic cation transport system, with approximately 50% of a dose excreted in the urine as unchanged drug. The remainder is metabolized to an active metabolite, n-acetyl procainamide (NAPA). Ofloxacin is a fluoroquinolone antibiotic that is excreted in the urine as unchanged drug via active tubular secretion and glomerular filtration. To test the hypothesis that ofloxacin may interfere with the renal elimination of procainamide, 9 healthy volunteers were randomly assigned to receive 1 g of oral procainamide as a single dose with or without pretreatment with 400 mg of ofloxacin twice a day for 5 doses. Blood and urine samples were obtained and pharmacokinetic parameters for procainamide were determined for each treatment period. Standard 12-lead and signal-averaged electrocardiographic recordings were used for pharmacodynamic analysis. The mean area under the concentration-time curve (AUC) and peak plasma concentration (Cmax; mug/mL) for procainamide increased by 27% and 21%, respectively, and the plasma clearance for procainamide decreased by an average of 22% with coadministration of ofloxacin. Ofloxacin did not significantly influence the pharmacokinetics of NAPA, nor were pharmacodynamics of procainamide significantly affected by coadministration of ofloxacin. These results suggest that procainamide concentrations should be monitored closely when coadministered with ofloxacin.

Effect of ACL Reconstruction and Tibial Rotation on Anterior Knee Laxity

The anterior cruciate ligament (ACL) is the primary restraint to anterior translation of the tibia on the femur. Research suggests that resistance to anterior translation changes as the tibia is rotated internally and externally. This study assessed the degree to which ACL reconstruction and tibial rotation affects anterior knee laxity. Nine subjects with ACL lesions and functional instabilities participated in the study. Subjects were measured 1 to 10 days before surgery and 6 to 8 months after ACL reconstruction using the KT-1000 knee arthrometer. A mechanical leg stabilizer was used to assess anterior translation at 20 degrees of knee flexion in three positions: internal rotation of 15 degrees , neutral, and external rotation of 15 degrees . Subjects were measured at 89 and 67 N of anterior force. Data were analyzed with a three-factor (test x position x force) repeated measures ANOVA. Following surgery, reduction in laxity (mm) for the three positions (internal rotation, neutral, and external rotation) was 1.9, 2.8, and 3.4, respectively, at 89 N and 1.5, 2.0, and 2.6, respectively, at 67 N. The degree of reduction in laxity (presurgery to postsurgery) was dependent upon rotation and force, and was greatest in external rotation and least in internal rotation pre- to postsurgery. We concluded that ACL reconstruction using a patellar tendon graft significantly decreased anterior tibial translation at all three positions, but a greater amount of reduction was observed postsurgically at the externally rotated position. This supports the theory that mechanical blocks and secondary restraints such as a taut mid-third of the iliotibial tract may interfere with clinical laxity tests in some positions of tibial rotation. Fixing the tibia in an externally rotated position may decrease the effect of secondary restraints and improve sensitivity in testing for ACL laxity.

Emergency medicine and the underage athlete

Most high school and some collegiate athletes are legal minors. In civil matters, the law treats minors (usually individuals under the age of 18 years) uniquely. Limitations exist on a minor's ability to enter into contracts, make determinations regarding medical care, and bear responsibility for personal actions. Medical professionals are often unclear on matters relating to the provision of medical care to minors. The purpose of this discourse is to present selected legal issues in the context of two fictional case studies. Case 1 presents issues regarding the definition of emergency medical conditions and the related emergency medical doctrine. Case 2 provides an example of an acute medical concern which fails to fall under emergency medical classification but rather provides a context for discussing the mature minor doctrine. Both cases are analyzed in light of these doctrines in addition to other pertinent legal considerations.

Glucose emergencies: recognition and treatment

Millions of Americans have pathologies related to glucose regulation. Many of these individuals have diagnosed diabetes. There are, however, countless others who are unaware that they have glucose regulation disorders. Athletic trainers may find themselves called upon to work with individuals with documented and undocumented disorders. The purpose of this article is to define three primary glucose emergencies (diabetic ketoacidosis, diabetic hyperosmolar state, and hypoglycemia) and discuss the treatment for each. Attention is focused on signs and symptoms which allow the athletic trainer to differentiate between the conditions.

Thiopental as an adjunct to hypothermia for EEG suppression in infants prior to circulatory arrest

Fifteen infants were studied to evaluate the effect of profound hypothermia (16 degrees C to 18 degrees C) and hypothermia plus thiopental on the electroencephalogram (EEG) prior to circulatory arrest. Mean patient age and weight were 5.5 +/- 1.2 months and 4.9 +/- 0.3 kg, respectively. After core cooling on cardiopulmonary bypass (CPB), all patients received thiopental, 8 mg/kg, 5 minutes prior to circulatory arrest. Satisfactory EEG recordings were obtained for 9 patients, and serum thiopental concentration was measured in 12 patients. Hypothermia (mean venous return temperature, 17.8 degrees C +/- 1.6 degrees C) alone was associated with persistent cerebral electrical activity in 8 of 9 patients (89%). The addition of thiopental, 8 mg/kg, produced an isoelectric EEG in 6 of these 8 patients (75%). Mean circulatory arrest duration was 44 +/- 4 minutes. EEG activity resumed after reinstitution of CPB in all patients. Serum thiopental concentration at the end of CPB was negligible. It is concluded that hypothermia alone often may not produce EEG isoelectricity, and that the associated cerebral metabolic activity may be suppressed by adjunctive use of thiopental.

Hemodynamic effects of muscle relaxant drugs during anesthetic induction in patients with mitral or aortic valvular heart disease

The hemodynamic effects of three nondepolarizing skeletal muscle relaxant drug regimens were compared during the induction of general anesthesia in 64 patients with valvular heart disease using a double-blind protocol. Patients were first stratified according to primary valvular defect (aortic stenosis, aortic regurgitation, mitral stenosis, or mitral regurgitation). Next, patients were randomly allocated to a drug group, either group A (atracurium), group V (vecuronium), or group MP (metocurine plus pancuronium). Data were collected during three periods: awake, postanesthetic induction, and posttracheal intubation. Four cardiovascular variables were designated a priori as primary variables of interest. These were heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), and systemic vascular resistance index (SVRI). Patients with mitral stenosis showed two significant hemodynamic differences among muscle relaxant drug groups: (1) CI increased in group A but decreased in group MP between the awake and postinduction measurements (P = 0.032); and (2) SVRI decreased in group A but increased in group MP between the awake and postintubation periods (P = 0.034). In contrast, patients with aortic stenosis, aortic regurgitation, or mitral regurgitation demonstrated no statistically significant difference in cardiovascular responses among drug groups. Further analysis was performed using the following data: (1) other hemodynamic variables; (2) incidence of deviations from cardiovascular stability; and (3) the frequency of cardiovascular drug use. This examination showed no important differences among the muscle relaxant drug groups. The small but significant hemodynamic changes observed in mitral stenosis patients in drug groups A and MP were not noted with vecuronium.(ABSTRACT TRUNCATED AT 250 WORDS)

The onset and duration of neuromuscular blockade using combinations of atracurium and vecuronium

The effect of atracurium-vecuronium combinations on the onset and duration of neuromuscular blockade was investigated in 30 adult patients undergoing general anaesthesia for elective surgery. The patients were randomized to receive either atracurium 0.6 mg.kg-1, vecuronium 0.1 mg.kg-1, or quarter-dose, half-dose, or full-dose combinations of the two drugs. Neuromuscular blockade was assessed by measuring the evoked electromyographic response of the abductor digiti minimi to transcutaneous stimulation of the ulnar nerve. It was found that half-dose combinations of atracurium and vecuronium did not produce a shorter onset time, but did result in a longer duration of neuromuscular blockade than full-doses of either drug alone (P less than 0.01). The quarter-dose combinations did not reduce onset time or increase duration. The full-dose combinations produced both a shorter onset time (P less than 0.01) and a longer duration (P less than 0.001). The results indicate that atracurium-vecuronium combinations are supra-additive in terms of the duration of the neuromuscular blockade produced. However, the inability of atracurium-vecuronium combinations to reduce onset time without increasing duration suggests that there is little advantage in combining the two drugs in clinical practice.

Brachymetatarsia. A new surgical approach

Although most practitioners are familiar with brachymetatarsia, it is a relatively uncommon clinical entity presenting for surgical correction. Traditional methods of surgical correction have been successful for the most part; however, a number of potentially devastating complications exist with these procedures. The authors present a review of the deformity, including the historical surgical techniques, and introduce a new surgical approach that minimizes the risk of complication.

Lesser metatarsalgia evaluation and treatment

Anatomic and biomechanical aspects of the complex topic of metatarsalgia are reviewed. Cause is classified as structural, functional, and a combination of both. Evaluation of the lesion symptom complex is presented and light is shed on reasons for complications after metatarsal osteotomy. Ways to avoid complications are also discussed. The oblique osteotomy with rigid fixation performed at the distal surgical neck or the proximal metaphysis is recommended.