Lopinavir/ritonavir reduces bupropion plasma concentrations in healthy subjects.

Limited data are available about the effect of steady-state lopinavir and ritonavir (LPV/r) on bupropion pharmacokinetics. As patients may benefit by using these two agents in combination, this study determined the extent and direction of this drug-drug interaction. Twelve healthy volunteers received a single 100 mg dose of sustained-release bupropion before and after 2 weeks of treatment with LPV/r 400 mg/100 mg twice daily. Pharmacokinetics profiles were determined on days 1 and 30 for bupropion and hydroxybupropion and days 29 and 30 for LPV/r. LPV/r administration significantly decreased bupropion maximum plasma concentration (C(max)) by 57% (90% confidence interval (CI), 38-76%; P<0.01) and area under the curve (AUC) infinity by 57% (90% CI, 32-83%; P<0.01). Hydroxybupropion C(max) and AUC infinity decreased by 31% (90% CI, 7-55%; P<0.01) and by 50% (90% CI, 34-65%; P<0.01), respectively. No significant changes in the pharmacokinetics of LPV/r were found following administration of a single dose of bupropion. Concurrent use of LPV/r and bupropion resulted in decreased exposure to bupropion and its active metabolite hydroxybupropion that may necessitate as much as a 100% dose increase of bupropion. A probable mechanism for this interaction is the concurrent induction of cytochrome P450 2B6 and UDP-glucuronosyltransferase enzymes. LPV/r exposure is unaffected by a single dose of bupropion.

Nuclear spin resonance of (129)Xe doped with O(2).

Spin-lattice relaxation of (129)Xe nuclei in solid natural xenon has been investigated in detail over a large range of paramagnetic O(2) impurity concentrations. Direct measurements of the ground state magnetic properties of the O(2) are difficult because the ESR (electron spin resonance) lines of O(2) are rather unstructured, but NMR measurements in the liquid helium temperature region (1.4-4 K) are very sensitive to the effective magnetic moments associated with the spin 1 Zeeman levels of the O(2) molecules and to the O(2) magnetic relaxation. From these measurements, the value of the D[Sz(2)-(1/3)S(2)] spin-Hamiltonian term of the triplet spin ground state of O(2) can be determined. The temperature and magnetic field dependence of the measured paramagnetic O(2)-induced excess line width of the (129)Xe NMR signal agree well with the theoretical model with the spin-Hamiltonian D=0.19 meV (2.3 K), and with the reasonable assumption that the E[S(x)(2)-S(y)(2)] spin-Hamiltonian term is close to 0 meV. An anomalous temperature dependence between 1.4 K and 4.2K of the (129)Xe spin-lattice relaxation rate, T(1n)(-1)(T), is also accounted for by our model. Using an independent determination of the true O(2) concentration in the Xe-O(2) solid, the effective spin lattice relaxation time (which will be seen to be transition dependent) of the O(2) at 2.3 K and 0.96 T is determined to be approximately 1.4 x 10(-8)s. The experimental results, taken together with the relaxation model, suggest routes for bringing highly spin-polarized (129)Xe from the low temperature condensed phase to higher temperatures without excessive depolarization.

Randomized, controlled trial of amitriptyline versus placebo for adolescents with "treatment-resistant" major depression.

OBJECTIVE: To assess the response to a serotonergic/noradrenergic tricyclic antidepressant, amitriptyline (AMI), in a group of adolescents with treatment-resistant major depressive disorder (MDD). METHOD: Twenty-seven depressed adolescents admitted to a state hospital underwent a 10-week randomized, controlled trial with a flexible dose of AMI or placebo. RESULTS: There were no differences between patients taking AMI (n = 13) and placebo (n = 14). Both treatment groups showed approximately 70% to 80% improvement on the clinical outcome measurements, and 65% to 70% showed functional improvement. At the end of the protocol, 30% of patients still fulfilled criteria for MDD and had impaired functioning. Patients taking AMI experienced significantly more dry mouth and tachycardia. The final AMI dose was 173.1 mg/day +/- 56.3 mg/day; blood levels were 226.2 ng/mL +/- 80.8 ng/mL. CONCLUSIONS: No significant differences were found between AMI and placebo, in part because of the high placebo response rate. Although both treatment groups showed substantial response, at the end of treatment a substantial proportion of patients still had MDD of subsyndromal symptoms of depression. This and other studies of tricyclic antidepressants question the use of this medication as first-line treatment for youths with MDD.

Continuous versus intermittent administration of ceftazidime in intensive care unit patients with nosocomial pneumonia.

A prospective, randomized pilot study was undertaken to compare the efficacy of continuous versus intermittent ceftazidime in ICU patients with nosocomial pneumonia. Ceftazidime was administered either as a 3 g/day continuous infusion (CI) or an intermittent infusion (II) of 2 g every 8 h. In addition, all patients received concomitant once-daily tobramycin. The demographics of the evaluable patients (n = 35) were similar between the groups: age (years), CI 46 +/- 16, II 56 +/- 20; Apache score, CI 14 +/- 4, II 16 +/- 6; time (days) from admission to diagnosis, CI 9 +/- 6, II 9 +/- 6. Clinical efficacy, defined as cure/improvement was similar between groups [n (%), CI 16/17 (94), II 15/18 (83)], while microbiological response was also comparable [n (%), CI 10/13 (76), II 12/15 (80)]. Minimal inhibitory concentrations (MICs) for all isolates were measured throughout the treatment course; there was no development of resistance during therapy for either regimen. While limited clinical data exist, our results suggest that the use of ceftazidime by CI administration maintains clinical efficacy, optimizes the pharmacodynamic profile and uses less antibiotic compared with the standard 2 g every 8 h intermittent dosing regimen.

Comparison of azithromycin leukocyte disposition in healthy volunteers and volunteers with AIDS.

Azithromycin, has been proved to be effective in the treatment and prophylaxis of a wide variety of infections. While the penetration of azithromycin into a number of types of mammalian cells has been well characterized, the influence of HIV infection on the intracellular disposition of this agent has not been studied. We therefore studied the disposition of azithromycin in polymorphonuclear (PMN) and mononuclear (MONO) leukocytes from six healthy volunteers and six volunteers with AIDS. After oral administration of a single 1200-mg dose of azithromycin (two 600-mg tablets), blood samples were collected over 6 days and intracellular azithromycin concentrations in MONOs and PMNs were measured. Analysis of the intracellular pharmacokinetics revealed an apparent difference in the MONO and PMN profile; this profile was similar for both groups. Intracellular concentrations of azithromycin remained high throughout the study period. Furthermore, no statistically significant differences in the intracellular area under the curve (11309+/-2543 vs. 16650+/-6254 for PMN; 14180+/-3802 vs. 21211+/-10001 for MONO) were observed between the healthy and AIDS populations, respectively. Our data confirm the extensive uptake of azithromycin by white blood cells both in healthy volunteers and in AIDS patients.

Cost-effectiveness of ceftazidime by continuous infusion versus intermittent infusion for nosocomial pneumonia.

STUDY OBJECTIVE: To determine if continuous-infusion ceftazidime is more cost-effective and efficacious than intermittent infusion in patients with nosocomial pneumonia. DESIGN: Prospective, open-label, randomized trial. SETTING: Large, community teaching hospital. PATIENTS: Intensive care unit (ICU) patients with nosocomial pneumonia. INTERVENTIONS: Ceftazidime 3 g/day was administered as a continuous infusion or as 2 g 3 times/day by intermittent infusion to treat nosocomial pneumonia in the ICU. Patients also received tobramycin 7 mg/kg once/day. MEASUREMENTS AND MAIN RESULTS: Thirty-five patients were evaluable; 17 received continuous infusion and 18 intermittent infusion. Clinical efficacy (94% and 83% successful outcomes with continuous and intermittent infusion, respectively), adverse events, and length of stay did not vary significantly between groups. Costs associated with continuous infusion, $627 +/- 388, were significantly lower (p < or = 0.001) than with intermittent infusion, $1007 +/- 430. CONCLUSIONS: Continuous infusion of ceftazidime is a cost-effective alternative to intermittent infusion for nosocomial pneumonia in the ICU.

Family involvement and outcome in treatment of alcoholism.

The purpose of the study was to determine the effect of spouses' (or significant others') involvement in the treatment of alcoholism. Altogether 80 adult patients who had been treated for alcoholism participated. There were three groups who varied in involvement: Group I whose spouses attended 3 or fewer group therapy sessions per week, Group II whose spouses attended 4 or more sessions per week, and Group III whose spouses were treated as inpatients for coalcoholism. Information was gathered through personal interviews as part of the treatment follow-up plan no less than six months after release. The results suggest strong associations between greater family involvement and abstinence (at least six months), better family relations, and positive feelings about self. Further work should consider factors contributing to greater spousal involvement and the nature of support received after treatment.

Quantitative microdialysis of ethanol in rat striatum.

We have applied a steady-state theory of microdialysis to characterize the diffusion of ethanol through a microdialysis membrane and through rat striatum. Quantitative characterization required measurement of in vitro and in vivo extraction fractions for ethanol and determination of the clearance of ethanol from brain tissue during steady-state perfusion through a microdialysis probe. Extraction fraction of ethanol was determined in vitro by perfusing a known concentration of ethanol through probes immersed in water at 37 degrees C with stirring. The in vitro extraction fraction yielded a probe permeability value of 0.046 +/- 0.004 cm/min that is comparable with an estimate from published measurements for similar dialysis membranes. The in vivo extraction fraction was determined for probes placed in the striatum. Clearance of ethanol and a brain slice concentration profile of ethanol were determined by measurement of the amount of ethanol remaining in the brain tissue during steady-state perfusion of the probe. Steady state was achieved within 10 min after beginning the ethanol perfusion in vivo, and the extraction fraction was not altered by sedation of the rat with pentobarbital. The tissue concentration profile was symmetrical around the probe track, and ethanol was detected 1 mm from the probe. The experimental clearance rate constant value obtained for ethanol (2.0 +/- 0.3 min(-1)) was higher than that expected for removal solely by loss to the blood. The tissue diffusivity for ethanol, Dt, derived from the experimental measurements was 1.2 +/- 0.2 x 10(-5) cm2/sec. This value is greater than expected for interstitial diffusion, suggesting a substantial contribution by transcellular diffusion of ethanol as well. The predicted tissue concentration profile had a higher peak value and did not extend into the tissue (0.5 mm) as much as the experimental profile (1 mm), although there was reasonable agreement between experiment and theory. Our quantitative characterization of the microdialysis behavior of ethanol in brain provides a framework for interpretation of brain microdialysis experiments using ethanol by supplying, inter alia, a means for estimating the ethanol concentration achieved in the tissue volume being sampled by the probe.

Mononuclear and polymorphonuclear leukocyte dispositions of clarithromycin and azithromycin in AIDS patients requiring Mycobacterium avium complex prophylaxis.

The intracellular dispositions of clarithromycin and azithromycin in AIDS patients requiring Mycobacterium avium complex (MAC) prophylaxis were studied. The dispositions of both drugs in mononuclear and polymorphonuclear leukocytes were markedly different. Our data support the proven efficacy of these agents for MAC prophylaxis since clarithromycin and azithromycin displayed sustained intracellular concentrations which exceeded their MICs for MAC throughout the dosing periods.

Comparison of the bactericidal activity of trovafloxacin and ciprofloxacin, alone and in combination with cefepime, against Pseudomonas aeruginosa.

BACKGROUND: Although ciprofloxacin exhibits more intense microbiological activity against Pseudomonas aeruginosa than does trovafloxacin, the clinical relevance of this observation remains questionable, particularly when the agents are combined with another antipseudomonal agent. METHODS: To evaluate this further, we conducted a four-way crossover trial to compare the bactericidal activities of ciprofloxacin and trovafloxacin, alone and in combination with cefepime, against three clinical isolates of P. aeruginosa. Healthy subjects received the following regimens, dosed to steady state: trovafloxacin 300 mg/24 h; ciprofloxacin 400 mg/12 h; trovafloxacin 300 mg/24 h plus cefepime 2 g/12 h, and ciprofloxacin 400 mg/12 h plus cefepime 2 g/12 h. Serum bactericidal titers were performed with each regimen. RESULTS: As monotherapy, the area under the bactericidal curve for ciprofloxacin exceeded that of trovafloxacin for all isolates. No significant difference in the overall degree of bactericidal activity was noted for two of three P. aeruginosa isolates for the combination regimens. Additionally, both combination regimens provided bactericidal activity for 100% of the dosing interval for all isolates. CONCLUSION: These results indicate that, while in vitro differences exist among these quinolones for P. aeruginosa, when a fluoroquinolone is combined with a beta-lactam, this is likely to be of little clinical significance.

HuA and tristetraprolin are induced following T cell activation and display distinct but overlapping RNA binding specificities.

AU-rich elements found in the 3'-untranslated regions of cytokine and proto-oncogene transcripts regulate mRNA degradation and function as binding sites for the mRNA-stabilizing protein HuA and the mRNA-destabilizing protein tristetraprolin. Experiments were performed to evaluate the expression of HuA and tristetraprolin in purified human T lymphocytes and to evaluate the ability of these proteins to recognize specific AU-rich sequences. HuA is a predominantly nuclear protein that can also be found in the cytoplasm of resting T lymphocytes. Within 1 h after stimulation of T lymphocytes with anti-T cell receptor antibodies or a combination of a phorbol myristate acetate and ionomycin, an increase in cytoplasmic HuA RNA-binding activity was observed. Although absent in resting cells, cytoplasmic tristetraprolin protein was detected 3-6 h following activation. HuA recognized specific AU-rich sequences found in c-jun or c-myc mRNA that were poorly recognized by tristetraprolin. In contrast, tristetraprolin recognized an AU-rich sequence in interleukin-2 mRNA that was poorly recognized by HuA. Both HuA and tristetraprolin, however, recognized AU-rich sequences from c-fos, interleukin-3, tumor necrosis factor-alpha, and granulocyte/macrophage colony-stimulating factor mRNA. HuA may transiently stabilize a subset of AU-rich element-containing transcripts following T lymphocyte activation, and tristetraprolin may subsequently mediate their degradation.

Adherence to highly active antiretroviral therapy predicts virologic outcome at an inner-city human immunodeficiency virus clinic.

This study's hypothesis is that human immunodeficiency virus-infected patients in the inner city (predominantly injection drug users and ethnic minorities) do not take highly active antiretroviral therapy (HAART) as prescribed and that nonadherence leads to virologic failure. A prospective, observational, 3-month study of adherence to HAART was undertaken at an inner-city clinic. There were 40 subjects [110 subject-months]; 30 were male, 10 were female, 75% were Hispanic, 23% were African American, 68% were injection drug users, and 68% were receiving triple therapy. At 3 months, adherence, which was determined by use of the Medication Event Monitoring System (Aprex) was significantly associated with virologic success: lower virus loads were associated with a rate of adherence of >80% (P<.05). Although nonadherence predicted virologic failure, virologic success was not always predicted by adherence: 11 (27.5%) of 40 subjects with suboptimal adherence rates (<90%) had complete virologic suppression.

Equivalence of microbial biomass measures based on membrane lipid and cell wall components, adenosine triphosphate, and direct counts in subsurface aquifer sediments.

An uncontaminated subsurface aquifer sediment contains a sparse microbial community consisting primarily of coccobacillary bacteria of relatively uniform size which can be counted directly with appropriate staining. The morphological simplicity and the relatively decreased cell numbers, when compared with surface soils and sediments, make the subsurface an ideal natural community with which to compare the utility of chemical measures of microbial biomass to direct microscopic counts. The membrane phospholipids (estimated as the polar lipid fatty acids, the lipid phosphate, and phosopholipid glycerol phosphate), lipopolysaccharide lipid A (estimated as the LPS hydroxy fatty acids), cell walls (estimated as the muramic acid), and adenosine triphosphate all give essentially identical estimates of cell numbers and dry weight as the direct counts, using conversion factors determined on subsurface microorganism monocultures. Assays of microbial cell components are thus validated by comparison with the classical direct count in at least one soil/sediment.

Streptococcus pneumoniae response to repeated moxifloxacin or levofloxacin exposure in a rabbit tissue cage model.

The role of moxifloxacin and levofloxacin pharmacokinetics (PK) in antimicrobial efficacy and in the selection of fluoroquinolone-resistant Streptococcus pneumoniae strains was investigated using the rabbit tissue cage abscess model. A rabbit tissue cage was created by insertion of sterile Wiffle balls in the dorsal cervical area. Animals orally received a range of moxifloxacin or levofloxacin doses that simulate human PK for 7 days 48 h after the Wiffle balls were inoculated with fluoroquinolone-sensitive S. pneumoniae (10(7) CFU). Abscess fluid was collected on a daily basis over 14 days to measure bacterial density and MICs. Moxifloxacin regimens produced a range of area under the concentration-time curve (AUC)/MIC ratios ranging from 9.2 to 444 and peak/MIC ratios ranging from 1.3 to 102. Levofloxacin doses produced AUC/MIC ratios of 5.1 to 85.5 and peak/MIC ratio of 0.9 to 14.8. Moxifloxacin at 6.5, 26, and 42 mg/kg reduced the bacterial log CFU per milliliter in abscess fluid (percentage of that in a sterile animal) by 4.2 +/- 2.2 (20%), 5.8 +/- 0.4 (100%), and 5.4 +/- 0.4 (100%), respectively, over the dosing period. Levofloxacin at 5.5, 22, and 32 mg/kg reduced the log CFU per milliliter in abscess fluid (percentage of that in a sterile animal) by 2.8 +/- 0.7 (20%), 5.1 +/- 1.3 (80%), and 4.6 +/- 1.3 (60%), respectively. Moxifloxacin has a greater bactericidal rate as determined by regression of log CFU versus time data. The AUC/MIC and peak/MIC ratios correlated with the efficacy of both drugs (P < 0.05). Resistance to either drug did not develop with any of the doses as assessed by a change in the MIC. In conclusion, data derived from this study show that moxifloxacin and levofloxacin exhibit rapid bactericidal activity against S. pneumoniae in vivo, and moxifloxacin exhibits enhanced bactericidal activity compared to levofloxacin, with AUC/MIC and peak/MIC ratios correlated with antimicrobial efficacy for both drugs. The development of fluoroquinolone-resistant S. pneumoniae was not observed with either drug in this model.

Observation of a (6)(LambdaLambda)He double hypernucleus.

A double-hyperfragment event has been found in a hybrid-emulsion experiment. It is identified uniquely as the sequential decay of ( 6)(LambdaLambda)He emitted from a Xi(-) hyperon nuclear capture at rest. The mass of ( 6)(LambdaLambda)He and the Lambda-Lambda interaction energy DeltaB(LambdaLambda) have been measured for the first time devoid of the ambiguities due to the possibilities of excited states. The value of DeltaB(LambdaLambda) is 1.01+/-0.20(+0.18)(-0.11) MeV. This demonstrates that the Lambda-Lambda interaction is weakly attractive.