Variability of voriconazole plasma levels measured by new high-performance liquid chromatography and bioassay methods

Voriconazole (VRC) is a broad-spectrum antifungal triazole with nonlinear pharmacokinetics. The utility of measurement of voriconazole blood levels for optimizing therapy is a matter of debate. Available high-performance liquid chromatography (HPLC) and bioassay methods are technically complex, time-consuming, or have a narrow analytical range. Objectives of the present study were to develop new, simple analytical methods and to assess variability of voriconazole blood levels in patients with invasive mycoses. Acetonitrile precipitation, reverse-phase separation, and UV detection were used for HPLC. A voriconazole-hypersusceptible Candida albicans mutant lacking multidrug efflux transporters (cdr1Delta/cdr1Delta, cdr2Delta/cdr2Delta, flu1Delta/flu1Delta, and mdr1Delta/mdr1Delta) and calcineurin subunit A (cnaDelta/cnaDelta) was used for bioassay. Mean intra-/interrun accuracies over the VRC concentration range from 0.25 to 16 mg/liter were 93.7% +/- 5.0%/96.5% +/- 2.4% (HPLC) and 94.9% +/- 6.1%/94.7% +/- 3.3% (bioassay). Mean intra-/interrun coefficients of variation were 5.2% +/- 1.5%/5.4% +/- 0.9% and 6.5% +/- 2.5%/4.0% +/- 1.6% for HPLC and bioassay, respectively. The coefficient of concordance between HPLC and bioassay was 0.96. Sequential measurements in 10 patients with invasive mycoses showed important inter- and intraindividual variations of estimated voriconazole area under the concentration-time curve (AUC): median, 43.9 mg x h/liter (range, 12.9 to 71.1) on the first and 27.4 mg x h/liter (range, 2.9 to 93.1) on the last day of therapy. During therapy, AUC decreased in five patients, increased in three, and remained unchanged in two. A toxic encephalopathy probably related to the increase of the VRC AUC (from 71.1 to 93.1 mg x h/liter) was observed. The VRC AUC decreased (from 12.9 to 2.9 mg x h/liter) in a patient with persistent signs of invasive aspergillosis. These preliminary observations suggest that voriconazole over- or underexposure resulting from variability of blood levels might have clinical implications. Simple HPLC and bioassay methods offer new tools for monitoring voriconazole therapy.     

Hippocampus-specific fMRI group activation analysis using the continuous medial representation

We present a new shape-based approach for regional group activation analysis in fMRI studies. The method restricts anatomical normalization, spatial smoothing and random effects statistical analysis to the space inside and around a structure of interest. Normalization involves finding intersubject correspondences between manually outlined masks, and it leverages the continuous medial representation, which makes it possible to extend surface-based shape correspondences to the space inside and outside of structures. Our approach is an alternative to whole-brain normalization in cases where the latter may fail due to anatomical variability or pathology. It also provides an opportunity to analyze the shape and thickness of structures concurrently with functional activation. We apply the technique to the hippocampus and evaluate it using data from a visual scene encoding fMRI study, where activation in the hippocampus is expected. We produce detailed statistical maps of hippocampal activation, as well as maps comparing activation inside and outside of the hippocampus. We find that random effects statistics computed by the new approach are more significant than those produced using the Statistical Parametric Mapping framework (Friston, K.J., Holmes, A.P., Worsley, K.J., Poline, J.-P., Firth, C.D., Frackowiak, R.S.J. 1994, Statistical parametric maps in functional imaging: a general linear approach. Human Brain Mapping, 2(4): 189-210) at low levels of smoothing, suggesting that greater specificity can be achieved by the new method without a severe tradeoff in sensitivity.     

High prevalence of metallo-beta-lactamase and 16S rRNA methylase coproduction among imipenem-resistant Pseudomonas aeruginosa isolates in Brazil

Rates of metallo-β-lactamase and 16S rRNA methylase production were investigated in 51 imipenem-resistant Pseudomonas aeruginosa clinical isolates collected from hospitals in São Paulo, Brazil. Of them, 57% and 75% produced SPM-1 and RmtD, respectively. Of note, 51% produced both enzymes, suggesting that their coproduction is already common in this geographic area.Treatment of infections due to Pseudomonas aeruginosa is becoming increasingly complicated by its tendency to acquire resistance to multiple classes of antimicrobials (12). The agents typically used to treat these infections include antipseudomonal penicillins, cephalosporins, carbapenems, fluoroquinolones, and aminoglycosides. The production of metallo-β-lactamases (MBLs) contributes substantially to panresistant phenotypes in P. aeruginosa because they confer resistance to all classes of β-lactam antimicrobials except aztreonam (10). Various MBLs including IMP, VIM, SPM, and GIM types have been reported for P. aeruginosa (12). Of note, SPM-type MBLs have been found only in Brazil thus far (13).Methylation of 16S rRNA has emerged as a mechanism of high-level aminoglycoside resistance among gram-negative pathogens in recent years (3). Five such methylases, ArmA and RmtA through RmtD, have been reported to date. The most recently identified methylase is RmtD, which we reported previously for a panresistant P. aeruginosa strain isolated near São Paulo, Brazil (4). This enzyme confers high-level resistance to most aminoglycosides in clinical use. In this particular strain, the coproduction of RmtD and SPM-1 played a substantial role in the panresistant phenotype. The present study was conducted to determine the prevalence of coproduction of these enzymes among P. aeruginosa clinical isolates in Brazil.Nonrepetitive imipenem-resistant P. aeruginosa isolates from a total of 49 patients hospitalized at seven hospitals in the São Paulo area in 2005 and 2006 were collected. One patient had two isolates with different pulsed-field gel electrophoresis (PFGE) patterns, and another patient had two isolates with identical PFGE patterns but markedly different susceptibility patterns. Thus, 51 imipenem-resistant P. aeruginosa isolates were included in the study. Sites of the specimens were as follows: 28 from urine, 8 from blood, 7 secretions from various sites, 3 from cerebrospinal fluid, 2 from catheter tip, 1 from bronchoalveolar lavage fluid, 1 from ascitic fluid, and 1 from nasal swab.The MICs of imipenem, meropenem, aztreonam, amikacin, gentamicin, arbekacin, ciprofloxacin, and colistin were obtained using either the standard agar dilution method or Etest (AB Biodisk, Solna, Sweden) (2). The MICs of imipenem were 32 μg/ml or higher for all the isolates, verifying the high degree of resistance to this agent in this collection. For meropenem, MICs were 8 μg/ml or higher. When the phenotypic test using sodium mercaptoacetic acid was performed to detect MBL production (1), 29 of 51 isolates (57%) yielded a positive result.PFGE was performed with SpeI (New England Biolabs, Beverly, MA) as the restriction enzyme for the genomic DNA. Electrophoresis was performed with the CHEF III DR system (Bio-Rad, Hercules, CA). The pulses were increased linearly from 5.3 to 34.9 s for 24 h at 14°C. Seventeen pulsotypes were observed among the 51 isolates by PFGE. Eight of the pulsotypes comprising 32 isolates from six hospitals were possibly related to each other (“pulsotype A,” consisting of subtypes A1 through A8), whereas the other nine pulsotypes were unrelated (pulsotypes B through J) according to criteria described previously by Tenover et al. (Table ​(Table11 and Fig. ​Fig.1)1) (14). Pulsotype A was thus the most prevalent genotype in hospitals in this area.Open in a separate windowFIG. 1.PFGE patterns of the study isolates. The pulsotypes were aligned using Bionumerics software version 4.0 (Applied Maths, Sint-Martens-Latem, Belgium).

TABLE 1.

Characteristics of study isolates

Peroxide bond-dependent antiplasmodial specificity of artemisinin and OZ277 (RBx11160)

Using nonperoxidic analogs of artemisinin and OZ277 (RBx11160), the strong in vitro antiplasmodial activities of the latter two compounds were shown to be peroxide bond dependent. In contrast, the weak activities of artemisinin and OZ277 against six other protozoan parasites were peroxide bond independent. These data support the iron-dependent artemisinin alkylation hypothesis.     

Daily functioning of dyspnea, self-esteem and physical self in patients with moderate COPD before, during and after a first inpatient rehabilitation program

PURPOSE: Inpatient rehabilitation improves dyspnea and increases self-esteem between admission and discharge in patients with moderate chronic obstructive pulmonary disease (COPD). Some researchers nevertheless argue that the changes may be due to nursing effects and thus that scores will decrease quickly at home after discharge. This study assessed the change in dyspnea, self-esteem and physical self mean scores and stability in patients with moderate COPD during three consecutive four-week periods: at home, during an inpatient rehabilitation program, and again at home post-discharge. METHODS: Twenty-three consecutive patients [63.9 years (SD 6.6)] with moderate COPD [FEV1 = 55.8% (SD 13.2)] were included. The participants responded to the Physical Self Inventory and rated dyspnea using a visual analogue scale twice a day. Exercise tolerance was assessed with the six-minute walk test (6MWT) at admission and discharge. RESULTS: 6MWT performance improved between admission and discharge [452.3 m. (SD 74.0) vs. 503.3 m. (SD 80.4), p < 0.001]. Dyspnea ratings improved (p < 0.001), as did the self-esteem and physical self scores between the two home periods (p < 0.001). The group showed less instability (SD and range) in their assessments of physical self-worth at home post-discharge compared to pre-admission (p < 0.01). Before rehabilitation, the correlation coefficients between dyspnea, and self-esteem, the perceptions of physical condition and attractive body were all significant. After rehabilitation, the coefficients between dyspnea, and perceived physical condition, physical strength and sport competence were significant (p < 0.05). CONCLUSIONS: The results suggest that a first rehabilitation program increases the mean physical self scores in patients with moderate COPD and decreases their instability; the program also improves dyspnea. However, the impact of rehabilitation was greater on specific perceptions of physical abilities than on the global self-esteem. Randomized controlled trials are needed to confirm these changes, which were probably due to rehabilitation program.     

AT1 receptor antagonist Candesartan in selected cirrhotic patients: effect on portal pressure and liver fibrosis markers

BACKGROUND/AIMS: The renin-angiotensin system plays an important role in hepatic fibrogenesis and in portal hypertension. To examine the long-term effects of Candesartan cilexetil, an angiotensin type 1 (AT1) receptor blocker, on portal-systemic haemodynamics and on liver fibrosis. METHODS: Forty-seven compensated Child A and Child B (8) cirrhotic patients were randomly assigned to receive Candesartan cilexetil, 8 mg/d (N.24) and no treatment (N.23) for 1 year. Portal-systemic haemodynamic parameters, serological levels of procollagen (PIIINP), hyaluronic acid (HA) and transforming growth factor beta 1 (TGFbeta1) were assessed at baseline and after 12 months. RESULTS: No patients discontinued or decreased the drug. The hepatic venous pressure gradient (HVPG) decreased significantly in treated patients (-8.4%+/-2.4) with a reduction >20% in 25% of cases vs+5.6%+/-2.9 in the untreated group. HA plasma levels decreased significantly in Candesartan treated patients in whom HVPG diminished and rose in untreated patients in whom HVPG increased. CONCLUSIONS: In selected cirrhotic patients, pharmacological inhibition of the AT1 receptor is well tolerated and induced a mild reduction of portal pressure. This haemodynamic effect might be related to liver fibrogenesis activity.     

Low-grade systemic inflammation causes endothelial dysfunction in patients with Hashimoto's thyroiditis

OBJECTIVE: The objective of this study was to assess whether low-grade systemic inflammation might contribute to the pathogenesis of endothelial dysfunction in patients with subclinical hypothyroidism (sHT) and autoimmune thyroiditis. BACKGROUND: sHT patients are characterized by peripheral endothelial dysfunction and low-grade inflammation. METHODS: In 53 sHT and 45 healthy subjects, we studied the forearm blood flow (strain-gauge plethysmography) response to intrabrachial acetylcholine (Ach) (0.15-15 microg/min.dl) with and without local vascular COX inhibition by intrabrachial indomethacin (50 microg/min.dl) or nitric oxide synthase blockade by N-mono methyl arginine (L-NMMA) (100 microg/min.dl) or the antioxidant vitamin C (8 mg/min.dl). The protocol was repeated 2 h after systemic nonselective COX inhibition (100 mg indomethacin) or selective COX-2 blockade (200 mg celecoxib) oral administrations. RESULTS: sHT patients showed higher C-reactive protein and IL-6 values. In controls, vasodilation to Ach was blunted by L-NMMA and unchanged by vitamin C. In contrast, in sHT, the response to Ach, reduced in comparison with controls, was resistant to L-NMMA and normalized by vitamin C. In these patients, systemic but not local indomethacin normalized vasodilation to Ach and the inhibition of L-NMMA on Ach. Similar results were obtained with celecoxib. When retested after indomethacin administration, vitamin C no longer succeeded in improving vasodilation to Ach in sHT patients. Response to sodium nitroprusside was unchanged by indomethacin or celecoxib. CONCLUSIONS: In sHT patients, low-grade chronic inflammation causes endothelial dysfunction and impaired nitric oxide availability by a COX-2-dependent pathway leading to increased production of oxidative stress.