bluuebunny/crossref_metadata_2025 huggingface dataset:
Patient-Specific 3D Finite-Element Analysis of Miniscrew Implants During Orthodontic Treatment
Authors: Ammar Hussein H. , Mucino Victor H. , Ngan Peter , Crout Richard J. , Mukdadi Osama M.
Published: June 2010

Miniscrew implants have seen increasing clinical use as orthodontic anchorage devices with demonstrated stability. The focus of this study is to develop and simulate operative factors, such as load magnitudes and anchor locations to achieve desired motions in a patient-specific 3D model undergoing orthodontic treatment with miniscrew implant anchorage. A CT scan of a patient skull was imported into Mimics software (Materialise, 12.1). Segmentation operations were performed on the images to isolate the mandible, filter out noise, then reconstruct a smooth 3D model. A model of the left canine was reconstructed with the PDL modeled as a thin solid layer. A miniscrew was modeled with dimensions based on a clinical implant (BMK OAS-T1207) then inserted into the posterior mandible. All components were volumetrically meshed and optimized in Mimics software. Elements comprising the mandible bone and teeth were assigned a material based on their gray value ranges in HU from the original scan, and meshes were exported into ANSYS software. All materials were defined as linear and isotropic. A nonlinear PDL was also defined for comparison. For transverse forces applied on the miniscrew, maximum stresses increased linearly with loading and appeared at the neck or first thread and in the cortical bone. A distal tipping force was applied on the canine, and maximum stresses appeared in the tooth at the crown and apex and in the bone at the compression surface. Under maximum loading, stresses in bone were sufficient for resorption. The nonlinear PDL exhibited lower stresses and deflections than the linear model due to increasing stiffness. Numerous stress concentrations were seen in all models. Results of this study demonstrate the potential of patient-specific 3D reconstruction from CT scans and finite-element simulation as a versatile and effective pre-operative planning tool for orthodontists.
Strain-Influenced Degradation of Native Collagenous Tissue in a Very-Low Volume, Environmentally-Controlled Bioreactor
Authors: Zareian Ramin , Saeidi Nima , Ruberti Jeffrey W.
Published: June 2010

We have hypothesized that collagenous matrix is an intrinsically smart biomaterial which resists enzymatic attack when under tensile strain. Testing this hypothesis requires the ability expose native tissue to low volumes of enzyme (due to their expense) while tracking mechanical response. In this study, we have developed an environmentally-controlled, mechanochemical bioreactor which permits load/strain tracking and direct observation of degrading tissue (polarization pictures) in a very small volume chamber (∼ 500 ul). In the device, the chamber “reaction volume” is formed between two layers of inert immiscible fluids. The device permitted exposure of the native tissue strips (∼6.0 mm × 0.7 mm × 13.5 mm) to small volumes of enzyme solution while it tracked the degradation-induced stress relaxation (to 0.01N accuracy) and provided direct observation of the tissue polarization signal. As expected in this small series, tissue with the higher (4% and 8%) strain degraded much more slowly compared to the lower (2%) strain. The new method successfully tracked collagen degradation (at high resolution) induced by a small volume of enzyme. The ability to perform these tests will permit the use of more expensive and physiologically relevant MMPs.
A High Throughput Microfluidic Thermal Reactor
Authors: Chen P.-C. , Park D. S. , You B. H. , Kim N. , Park T. , Nikitopoulos D. E. , Soper S. A. , Murphy M. C.
Published: June 2010

A high throughput microfluidic system including a 96 continuous flow (CF) thermal reactors and a multi-zone thermal control system was designed and fabricated. An infrared camera (IR) was used to analyze and verify the uniformity of the temperature distribution. Temperature variations from the nominal values were ±2°C in the denaturation zone and ±1°C in the renaturation and extension zones. Six different DNA fragments, with lengths ranging from 99 bp to 997 bp, were obtained from a λ-DNA template, each with a distinct renaturation temperature. As an initial demonstration of the biochemical performance of the polymerase chain reaction (PCR) reactor arrays, a column device comprised of eight 25-cycle CFPCRs was used to amplify identical PCR cocktails for each DNA fragment simultaneously at a flow velocity of 2 mm/s. All but the 997 bp were successfully amplified. Yields for the 99 bp fragment varied from 15%–36% of the amplicon on block thermal cycler. In a second experiment, a row device composed of six 25-cycle CFPCRs was used to successfully, simultaneously amplify cocktails for all six DNA fragment lengths at a flow velocity of 1 mm/s in parallel. Each device in the row had a distinct renaturation temperature to match the DNA fragment length. The parallel thermal arrays can be used in modular systems including both PCR for amplification and, for example, ligase detection reaction (LDR) for mutation detection.
Dynamic Mechanical Response of Renal Cortex Under Compression: Strain-Rate Effect
Authors: Pervin Farhana , Chen Weinong W. , Weerasooriya Tusit
Published: June 2010

The body armor can protect the soldiers from penetrating and blunt injury during the war, but its prevention standard lacks the biomedical validity. To improve the protection gear and prevention strategies, we need valid input data in mathematical modeling at different impact loading conditions. Our aim is to provide the valid data for the computer modeling and simulation based on the injury levels. Dynamic mechanical behaviors of kidney tissues are needed as input data for the impact modeling of penetrating injury. Moreover, the knowledge of mechanical responses of kidney tissues is important for diagnosis, surgical simulation and training purposes. This work investigates the impact of strain rate effect of kidney tissue under compression. The dynamic response of kidney tissues is studied using Split Hopkinson pressure bar (SHPB) technique. We have modified the classical SHPB technique to characterize the mechanical behavior of kidney tissues at high strain-rate ranging from 1000 s−1 to 3000 s−1 by incorporating quratz-crystal technique and hollow transmission bar. We have also studied the quasi-static response of kidney tissues at three different strain-rates of 0.01 s−1, 0.1 s−1 and 1 s−1 as well as the intermediate strain rate at two different strain rates of 10 s−1 and 100s−1. The experiment results indicate the non-linear stress-strain response of materials. The kidney tissue stiffens evidently with increasing strain-rate.
In Vivo Measurements of Change in Viscoelasticity of Arterial Wall During the Flow-Mediated Dilation
Authors: Kanai Hiroshi , Hasegawa Hideyuki , Ikeshita Kazuki
Published: June 2010

The present paper introduces in vivo measurements of viscoelasticity of arterial wall developed in our laboratory. The endothelial dysfunction is considered to be an earliest stage of atherosclerosis. Moreover, it was reported that the smooth muscle, which constructs the media of the artery, changes its characteristics due to atherosclerosis. Therefore, it is essential to develop an in vivo measurement method to assess the regional endothelial function and mechanical property (viscoelasticity) of the arterial wall. To evaluate the endothelial function, there is a conventional technique for measuring the transient change in the diameter of the brachial artery caused by flow mediated dilation (FMD) after the release of avascularization. However, this method does not directly evaluate the viscoelasticity of the intima-media region of the arterial wall. In the present paper, therefore, we proposed a method for simultaneous measurement of waveforms of the radial strain and blood pressure at the radial artery, and we developed its measurement system. From in vivo experiments, the viscoelasticity parameters of the arterial wall were estimated from the measured stress-strain relationship (hysteresis loop) using the least-square method and their transient changes after the release of avascularization were revealed. For healthy young persons, the slope of the hysteresis loop decreased due to the FMD, which corresponds to decrease in the elastic modulus. At the same time, the area of the loop increased after recirculation, which corresponds to the increase of the ratio of the loss modulus (viscosity) to the elastic modulus when the Voigt model is assumed. These results show a potential of the proposed method for thorough analysis of the transient change in viscoelasticity due to FMD.
Ablation of the Kinase NDR1 Predisposes Mice to the Development of T Cell Lymphoma
Authors: Cornils Hauke , Stegert Mario R. , Hergovich Alexander , Hynx Debby , Schmitz Debora , Dirnhofer Stephan , Hemmings Brian A.
Published: June 2010

The kinase NDR1 functions as a haploinsufficient tumor suppressor by ensuring proper apoptotic responses.
Taking AIM at Adipocytes
Authors: Foley John F.
Published: June 2010

The macrophage-derived protein AIM is taken up by adipocytes and induces a reduction in adipose tissue mass.
Seeing EPO
Authors: Ray L. Bryan
Published: June 2010

Modeling and experiments help explain responsiveness of red blood cell precursors to very large changes in a proliferative signal.
Analysis of Matrix-Dependent Cell Migration with a Barrier Migration Assay
Authors: Kroening Sven , Goppelt-Struebe Margarete
Published: June 2010

Removable plastic barriers allow quantification of cell migration without damaging either the surface proteins or the cells.
Experimental Murine Scedosporiosis: Histopathology and Azole Treatment
Authors: Rodríguez M. Mar , Pastor F. Javier , Salas Valentina , Calvo Enrique , Mayayo Emilio , Guarro Josep
Published: June 2010

The histopathology of clinical isolates of
Scedosporium apiospermum
,
Scedosporium boydii
, and
Scedosporium aurantiacum
in immunosuppressed mice was evaluated. The organs most affected were the brain, kidneys, and spleen.
S. aurantiacum
produced more tissue damage than the other two species. Amphotericin B (AMB) was ineffective in the treatment of murine infections caused by such isolates, and posaconazole and voriconazole showed efficacy that correlated with the
in vitro
susceptibility data.
Extended-Spectrum Cephalosporinase in
Acinetobacter baumannii
Authors: Rodríguez-Martínez José-Manuel , Nordmann Patrice , Ronco Esthel , Poirel Laurent
Published: June 2010

An AmpC-type β-lactamase conferring high-level resistance to expanded-spectrum cephalosporins and monobactams was characterized from an
Acinetobacter baumannii
clinical isolate. This class C β-lactamase (named ADC-33) possessed a Pro210Arg substitution together with a duplication of an Ala residue at position 215 (inside the Ω-loop) compared to a reference AmpC cephalosporinase from
A. baumannii
. ADC-33 hydrolyzed ceftazidime, cefepime, and aztreonam at high levels, which allows the classification of this enzyme as an extended-spectrum AmpC (ESAC). Site-directed mutagenesis confirmed the role of both substitutions in its ESAC property.
Baseline Genotypic and Phenotypic Susceptibilities of HIV-1 Group O to Enfuvirtide
Authors: Depatureaux Agnès , Charpentier Charlotte , Collin Gilles , Leoz Marie , Descamps Diane , Vessière Aurélia , Damond Florence , Rousset Dominique , Brun-Vézinet Françoise , Plantier Jean-Christophe
Published: June 2010

We assessed the natural genotypic and phenotypic susceptibilities to enfuvirtide of 171 HIV group O (HIV-O) samples and 29 strains, respectively. The N42D resistance-associated mutation in the gp41 region was detected in 98% of cases. The phenotypic assay showed a wide range of baseline susceptibilities, with 50% inhibitory concentrations (IC50s) from 4 to 5,000 nM, a range similar to that reported for HIV-1 group M. Thus, despite the natural genotypic resistance conferred by the N42D signature mutation, HIV-O variants appear to be phenotypically susceptible. Enfuvirtide could therefore potentially be used in antiretroviral treatments for HIV-O-infected patients.
Therapeutic Drug Monitoring of Posaconazole in Hematology Patients: Experience with a New High-Performance Liquid Chromatography-Based Method
Authors: Neubauer Werner Christian , Engelhardt Monika , König Armin , Hieke Stefanie , Jung Manfred , Bertz Hartmut , Kümmerer Klaus
Published: June 2010

Parallel administration of the proton pump inhibitor (PPI) esomeprazole has been shown to decrease oral bioavailability of posaconazole in healthy volunteers. We prospectively analyzed serum samples (
n
= 59) obtained from hematology patients (
n
= 27) under posaconazole prophylaxis. Patients treated concomitantly with pantoprazole had significantly lower posaconazole levels than patients without PPI treatment (median levels of 630 μg/liter versus 1,125 μg/liter, respectively). These results suggest that drug monitoring is relevant when posaconazole and pantoprazole are administered concomitantly.
Absence of Association between Piperaquine
In Vitro
Responses and Polymorphisms in the
pfcrt
,
pfmdr1
,
pfmrp
, and
pfnhe
Genes in
Plasmodium falciparum
Authors: Briolant Sébastien , Henry Maud , Oeuvray Claude , Amalvict Rémy , Baret Eric , Didillon Eric , Rogier Christophe , Pradines Bruno
Published: June 2010

We have analyzed the profiles of 23 of
Plasmodium falciparum
strains for their
in vitro
chemosusceptibilities to piperaquine (PPQ), dihydroartemisinin (DHA), chloroquine, monodesethylamodiaquine, quinine, mefloquine, lumefantrine, atovaquone, pyrimethamine, and doxycycline (DOX) in association with polymorphisms in genes involved in quinoline resistance (
Plasmodium falciparum crt
[
pfcrt
],
pfmdr1
,
pfmrp
, and
pfnhe
). The 50% inhibitory concentrations (IC
50
s) for PPQ ranged from 29 to 98 nM (geometric mean = 57.8 nM, 95% confidence interval [CI] = 51 to 65) and from 0.4 to 5.8 nM for DHA (geometric mean = 1.8 nM, 95% CI = 1.4 to 2.3). We found a significant positive correlation between the responses to PPQ and DHA (
r
2
= 0.17;
P
= 0.0495) and between the responses to PPQ and DOX (
r
2
= 0.41;
P
= 0.001). We did not find a significant association between the PPQ IC
50
(0.0525 <
P
< 0.9247) or the DHA IC
50
(0.0138 <
P
< 0.9018) and polymorphisms in the
pfcrt
,
pfmdr1
,
pfmrp
, and
pfnhe-1
genes. There was an absence of cross-resistance with quinolines, and the IC
50
s for PPQ and DHA were found to be unrelated to mutations in the
pfcrt
,
pfmdr1
,
pfmrp
, and
pfnhe-1
transport protein genes, which are involved in quinoline antimalarial drug resistance. These results confirm the interest in and the efficacy of the combination of PPQ and DHA for areas in which parasites are resistant to chloroquine or other quinolines.
Foreign Travel Is a Major Risk Factor for Colonization with
Escherichia coli
Producing CTX-M-Type Extended-Spectrum β-Lactamases: a Prospective Study with Swedish Volunteers
Authors: Tängdén Thomas , Cars Otto , Melhus Åsa , Löwdin Elisabeth
Published: June 2010

Foreign travel has been suggested to be a risk factor for the acquisition of extended-spectrum beta-lactamase (ESBL)-producing
Enterobacteriaceae
. To our knowledge, this has not previously been demonstrated in a prospective study. Healthy volunteers traveling outside Northern Europe were enrolled. Rectal swabs and data on potential travel-associated risk factors were collected before and after traveling. A total of 105 volunteers were enrolled. Four of them did not complete the study, and one participant carried ESBL-producing
Escherichia coli
before travel. Twenty-four of 100 participants with negative pretravel samples were colonized with ESBL-producing
Escherichia coli
after the trip. All strains produced CTX-M enzymes, mostly CTX-M-15, and some coproduced TEM or SHV enzymes. Coresistance to several antibiotic subclasses was common. Travel to India was associated with the highest risk for the acquisition of ESBLs (88%;
n
= 7). Gastroenteritis during the trip was an additional risk factor (
P
= 0.003). Five of 21 volunteers who completed the follow-up after 6 months had persistent colonization with ESBLs. This is the first prospective study demonstrating that international travel is a major risk factor for colonization with ESBL-producing
Enterobacteriaceae
. Considering the high acquisition rate of 24%, it is obvious that global efforts are needed to meet the emergence and spread of CTX-M enzymes and other antimicrobial resistances.
Using Population Pharmacokinetics To Determine Gentamicin Dosing during Extended Daily Diafiltration in Critically Ill Patients with Acute Kidney Injury
Authors: Roberts Jason A. , Field Jonathan , Visser Adam , Whitbread Rosemary , Tallot Mandy , Lipman Jeffrey , Kirkpatrick Carl M. J.
Published: June 2010

The objective of the present prospective pharmacokinetic study was to describe the variability of plasma gentamicin concentrations in critically ill patients with acute kidney injury (AKI) necessitating extended daily diafiltration (EDD-f) using a population pharmacokinetic model and to subsequently perform Monte Carlo dosing simulations to determine which dose regimen achieves the pharmacodynamic targets the most consistently. We collected data from 28 gentamicin doses in 14 critically ill adult patients with AKI requiring EDD-f and therapeutic gentamicin. Serial plasma samples were collected. A population pharmacokinetic model was used to describe the pharmacokinetics of gentamicin and perform Monte Carlo simulations with doses of between 3 mg/kg of body weight and 7 mg/kg and at various time points before commencement of EDD-f to evaluate the optimal dosing regimen for achieving pharmacodynamic targets. A two-compartment pharmacokinetic model adequately described the gentamicin clearance while patients were on and off EDD-f. The plasma half-life of gentamicin during EDD-f was 13.8 h, whereas it was 153.4 h without EDD-f. Monte Carlo simulations suggest that dosing with 6 mg/kg every 48 h either 30 min or 1 h before the commencement of EDD-f results in 100% attainment of the target maximum concentration drug in plasma (<10 mg/liter) and sufficient attainment of the target area under the concentration-time curve from 0 to 24 h (AUC
0-24
; 70 to 120 mg·h/liter). None of the simulated dosing regimens satisfactorily achieved the targets of the minimum concentrations of drug in plasma (<1.0 mg/liter) at 24 h. In conclusion, dosing of gentamicin 30 min to 1 h before the commencement of an EDD-f treatment enables attainment of target peak concentrations for maximal therapeutic effect while enhancing drug clearance to minimize toxicity. Redosing in many patients should occur after 48 h, and we recommend the use of therapeutic drug monitoring to guide dosing to optimize achievement of the AUC
0-24
targets.
Affinity of the New Cephalosporin CXA-101 to Penicillin-Binding Proteins ofPseudomonas aeruginosa
Authors: Moyá Bartolomé , Zamorano Laura , Juan Carlos , Ge Yigong , Oliver Antonio
Published: June 2010

CXA-101, previously designated FR264205, is a new antipseudomonal cephalosporin. The objective of this study was to determine the penicillin-binding protein (PBP) inhibition profile of CXA-101 compared to that of ceftazidime (PBP3 inhibitor) and imipenem (PBP2 inhibitor). Killing kinetics, the induction of AmpC expression, and associated changes on cell morphology were also investigated. The MICs for CXA-101, ceftazidime, and imipenem were 0.5, 1, and 1 μg/ml, respectively. Killing curves revealed that CXA-101 shows a concentration-independent bactericidal activity, with concentrations of 1× the MIC (0.5 μg/ml) producing a >3-log reduction in bacterial load after 8 h of incubation. Live-dead staining showed that concentrations of CXA-101 as low as 0.5× the MIC stopped bacterial septation and induced an intense filamentation, which is consistent with the documented high affinity of PBP3. CXA-101 was found to be a potent PBP3 inhibitor and showed affinities ≥2-fold higher than those of ceftazidime for all of the essential PBPs (1b, 1c, 2, and 3). Compared to imipenem, in addition to the obvious inverse PBP2/PBP3 affinities, CXA-101 showed a significantly higher affinity for PBP1b but a lower affinity for PBP1c. Furthermore, CXA-101, like ceftazidime and in contrast to imipenem, was found to be a very weak inducer of AmpC expression, consistent with the low PBP4 affinity documented.
T-2307 Shows Efficacy in a Murine Model of
Candida glabrata
Infection despite
In Vitro
Trailing Growth Phenomena
Authors: Yamada Eio , Nishikawa Hiroshi , Nomura Nobuhiko , Mitsuyama Junichi
Published: June 2010

T-2307, a novel arylamidine, has been shown to exhibit broad-spectrum
in vitro
and
in vivo
antifungal activities against clinically significant pathogens. In our preliminary studies,
Candida glabrata
exhibited significant trailing growth (partial inhibition of growth over an extended range of antifungal concentrations) in the presence of T-2307 when it was tested using the Clinical and Laboratory Standards Institute (CLSI) guidelines with 0.2% glucose and 48 h of incubation, making reading of the MIC difficult. In the present study, we attempted to attenuate trailing growth to avoid misreading of the MIC. On the basis of the hypothesis that T-2307 may inhibit the mitochondrial functions of cells, the carbon source or the glucose concentration in the medium was changed. The trailing growth of
C. glabrata
ATCC 90030 in the presence of T-2307 was attenuated as the concentration of glucose in the medium decreased to 0.1% or lower, and trailing growth was completely inhibited when glycerol was used. A susceptibility test using Alamar blue was performed to facilitate reading of the MIC without changing the composition of the medium and provided a clear MIC endpoint at 24 h. To investigate if T-2307 shows efficacy against trailing isolates
in vivo
, we evaluated the efficacy of T-2307 in a murine model of disseminated candidiasis caused by
C. glabrata
. T-2307 at 0.05 mg/kg of body weight/day significantly decreased the viable count in the kidneys compared to that for the control group (
P
< 0.05). It would be better to test the susceptibility of
C. glabrata
to T-2307 using modified media or Alamar blue to avoid misreading of the MIC due to the significant trailing growth.
Aerosol Therapy with Colistin Methanesulfonate: a Biopharmaceutical Issue Illustrated in Rats
Authors: Marchand Sandrine , Gobin Patrice , Brillault Julien , Baptista Sara , Adier Christophe , Olivier Jean-Christophe , Mimoz Olivier , Couet William
Published: June 2010

The aim of this study was to evaluate the biopharmaceutical behavior of colistin methanesulfonate (CMS) with special focus on colistin presystemic formation after CMS nebulization in rats. CMS was administered (15 mg·kg
−1
of body weight) either intravenously for systemic pharmacokinetic studies (
n
= 6) or as an intratracheal nebulization for systemic pharmacokinetic studies (
n
= 5) or for CMS and colistin concentration measurements in epithelial lining fluid (ELF) at 30, 120, and 240 min after nebulization (
n
= 14). CMS and colistin concentrations were determined by a new liquid chromatography (LC)-tandem mass spectrometry (MS/MS) assay. Pharmacokinetic parameters were estimated by noncompartmental analysis. CMS and colistin pharmacokinetic data were consistent with previously published values when comparisons were possible. The fraction of the CMS dose converted systematically into colistin after intravenous CMS administration was estimated to be 12.5% on average. After CMS nebulization it was estimated that about two-thirds of the dose was directly absorbed within the systemic circulation, whereas one-third was first converted into active colistin, which was eventually absorbed. As a consequence, the colistin area under curve (AUC) reflecting systemic availability was about 4-fold greater after CMS intratracheal nebulization (607 ± 240 μg·min·ml
−1
) than after CMS intravenous administration (160 ± 20 μg·min·ml
−1
). CMS concentrations in ELF at 30 min and 120 min postnebulization were very high (in the order of several mg/ml) due to the limited volume of ELF but were considerably reduced at 240 min. Although lower (15% ± 5% at 120 min) in relative terms, colistin concentrations in ELF could be high enough for being active against microorganisms following CMS nebulization.
Stereoselective Phosphorylation of Cyclopropavir by pUL97 and Competitive Inhibition by Maribavir
Authors: Gentry Brian G. , Kamil Jeremy P. , Coen Donald M. , Zemlicka Jiri , Drach John C.
Published: June 2010

Human cytomegalovirus (HCMV) is a widespread pathogen that can cause severe disease in immunologically immature and immunocompromised individuals. Cyclopropavir (CPV) is a guanine nucleoside analog active against human and murine cytomegaloviruses in cell culture and efficacious in mice by oral administration. Previous studies established that the mechanism of action of CPV involves inhibition of viral DNA synthesis. Based upon this action and the structural similarity of CPV to ganciclovir (GCV), we hypothesized that CPV must be phosphorylated to a triphosphate to inhibit HCMV DNA synthesis and that pUL97 is the enzyme responsible for the initial phosphorylation of CPV to a monophosphate (CPV-MP). We found that purified pUL97 phosphorylated CPV 45-fold more extensively than GCV, a known pUL97 substrate and the current standard of treatment for HCMV infections. Kinetic studies with CPV as the substrate for pUL97 demonstrated a

K
m

of 1,750 ± 210 μM. Introduction of 1.0 or 10 nM maribavir, a known pUL97 inhibitor, and subsequent Lineweaver-Burk analysis demonstrated competitive inhibition of CPV phosphorylation, with a

K
i

of 3.0 ± 0.3 nM. Incubation of CPV with pUL97 combined with GMP kinase [known to preferentially phosphorylate the (+)-enantiomer of CPV-MP] established that pUL97 stereoselectively phosphorylates CPV to its (+)-monophosphate. These results elucidate the mechanism of CPV phosphorylation and help explain its selective antiviral action.
Generic Vancomycin Products FailIn Vivodespite Being Pharmaceutical Equivalents of the Innovator
Authors: Vesga Omar , Agudelo Maria , Salazar Beatriz E. , Rodriguez Carlos A. , Zuluaga Andres F.
Published: June 2010

Generic versions of intravenous antibiotics are not required to demonstrate therapeutic equivalence with the innovator because therapeutic equivalence is assumed from pharmaceutical equivalence. To test such assumptions, we studied three generic versions of vancomycin in simultaneous experiments with the innovator and determined the concentration and potency of the active pharmaceutical ingredient by microbiological assay, single-dose pharmacokinetics in infected mice, antibacterial effect by broth microdilution and time-kill curves (TKC), and pharmacodynamics against two wild-type strains ofStaphylococcus aureusby using the neutropenic mouse thigh infection model. The main outcome measure was the comparison of magnitudes and patterns ofin vivoefficacy between generic products and the innovator. Except for one product exhibiting slightly greater concentration, vancomycin generics were undistinguishable from the innovator based on concentration and potency, protein binding,in vitroantibacterial effect determined by minimal inhibitory or bactericidal concentrations and TKC, and serum pharmacokinetics. Despite such similarities, all generic products failedin vivoto killS. aureus, while the innovator displayed the expected bactericidal efficacy: maximum antibacterial effect (Emax) (95% confidence interval [CI]) was 2.04 (1.89 to 2.19), 2.59 (2.21 to 2.98), and 3.48 (2.92 to 4.04) versus 5.65 (5.52 to 5.78) log10CFU/g for three generics and the innovator product, respectively (P< 0.0001, any comparison). Nonlinear regression analysis suggests that generic versions of vancomycin contain inhibitory and stimulatory principles within their formulations that cause agonistic-antagonistic actions responsible forin vivofailure. In conclusion, pharmaceutical equivalence does not imply therapeutic equivalence for vancomycin.
Contribution of BlaA and BlaB β-Lactamases to Antibiotic Susceptibility of
Yersinia enterocolitica
Biovar 1B
Authors: Bent Zachary W. , Young Glenn M.
Published: June 2010

Highly pathogenic
Yersinia enterocolitica
biovar 1B produces two distinct β-lactamases, BlaA and BlaB. Mutants of a representative biovar 1B isolate were constructed and evaluated to determine the extent of limitation of susceptibility to broad-spectrum β-lactam antibiotics by BlaA and BlaB. The results demonstrated that BlaA, a class A enzyme, plays a significant role in limiting susceptibility to penicillins and cephalosporins. The contribution of BlaB, a class C enzyme, was less profound and was limited primarily to cephalosporin susceptibility.
Translocation of
Porphyromonas gingivalis
Gingipain Adhesin Peptide A44 to Host Mitochondria Prevents Apoptosis
Authors: Boisvert Heike , Duncan Margaret J.
Published: June 2010

Porphyromonas gingivalis
, a Gram-negative oral anaerobe, is associated with periodontal diseases that, in some form, affect up to 80% of the U.S. population. The organism is highly proteolytic, and noncatalytic adhesin domains of the major proteases, gingipains, are involved in bacterium-host interactions. Recently, we showed that gingipain adhesin peptide A44 hijacks the host's clathrin-dependent endocytosis system, allowing the peptide and whole bacteria to be internalized by epithelial cells. In the present study, we found by cell fractionation assays and confocal microscopy that peptide A44 translocated to host mitochondria. Cell viability assays and quantitative real-time PCR showed that the peptide interacted with the cell death machinery by triggering upregulation of antiapoptotic factors
bcl-2
and
bcl-XL
and prevented staurosporine-induced apoptosis for up to 12 h. We confirmed these findings with Western blot analyses of caspase-9 activation in time course experiments with staurosporine. Finally, we verified a similar antiapoptotic effect for
P. gingivalis
, showing for the first time that the organism manipulated mitochondrial functions during the first hours of infection, thus resisting host cell clearance by apoptosis of infected cells. This mechanism may enable the bacteria to persist in the protected cellular environment until the next step in pathogenesis, progression or resolution of infection.
Role of PknB Kinase in Antibiotic Resistance and Virulence in Community-Acquired Methicillin-Resistant
Staphylococcus aureus
Strain USA300
Authors: Tamber Sandeep , Schwartzman Joseph , Cheung Ambrose L.
Published: June 2010

The regulation of cellular processes by eukaryote-like serine/threonine kinases is widespread in bacteria. In the last 2 years, several studies have examined the role of serine/threonine kinases in
Staphylococcus aureus
on cell wall metabolism, autolysis, and virulence, mostly in
S. aureus
laboratory isolates in the 8325-4 lineage. In this study, we showed that the
pknB
gene (also called
stk1
) of methicillin-resistant
S. aureus
(MRSA) strain COL and the community-acquired MRSA (CA-MRSA) strain USA300 is involved in cell wall metabolism, with the
pknB
mutant exhibiting enhanced sensitivity to β-lactam antibiotics but not to other classes of antibiotics, including aminoglycosides, ciprofloxacin, bactrim, and other types of cell wall-active agents (e.g., vancomycin and bacitracin). Additionally, the
pknB
mutant of USA300 was found to be more resistant to Triton X-100-induced autolysis and also to lysis by lysostaphin. We also showed that
pknB
is a positive regulator of
sigB
activity, resulting in compromise in its response to heat and oxidative stresses. In association with reduced
sigB
activity, the expression levels of RNAII and RNAIII of
agr
and the downstream effector
hla
are upregulated while
spa
expression is downmodulated in the
pknB
mutant compared to the level in the parent. Consistent with an enhanced
agr
response
in vitro
, virulence studies of the
pknB
mutant of USA300 in a murine cutaneous model of infection showed that the mutant was more virulent than the parental strain. Collectively, our results have linked the
pknB
gene in CA-MRSA to antibiotic resistance,
sigB
activity, and virulence and have highlighted important differences in
pknB
phenotypes (virulence and
sigB
activity) between laboratory isolates and the prototypic CA-MRSA strain USA300.
Acidobasic equilibria in 9-(3’-pyridyl)-2,6,7-trihydroxy-3H-xanthene-3-one solutions in the presence of surfactants
Authors: Kult Karel , Vrbský Jaromír
Published: June 2010

The effects of cationic tenside Septonex and the non-ionic tenside polyvinylpyrrolidone on the acidobasic and spectral properties of 3-pyridylfluorone have been studied. Data for the dependence A = f(pH*) were used to calculate protonization constants and molar absorption coefficients of the various acidobasic forms of 3-pyridylfluorone in solution with c(Septonex) = 5 mmol 1-1 or ρ(polyvinylpyrrolidone) = 1 g l-1 in 10% (v/v) methanol adjusted by sodium chloride to an ionic strength I 0.2. The results are compared with protonization constants of the reagent in solutions of the same ionic strength and methanol concentrations but without a surfactant. The effects of the tensides on the shape of absorption spectra of the various acidobasic forms of the reagent are also discussed.
A new adhesive protein mediating the interaction between mesenchymal cells and elastin fibers: Elastonectin
Authors: Robert Ladislas , Hornebeck William
Published: June 2010

An inducible adhesive protein was demonstrated in smooth muscle cells and fibroblasts which mediate the adhesion of mesenchymal cells to elastic fibers. It is proposed to designate it elastonectin. This protein plays probably an important role in the morphogenesis of elastic tissue and its degradation is probably involved in the formation of the atherosclerotic plaque.
Aminoalkylidene and aminoalkyl derivatives of 6,11-dihydrodibenzo[b,e]thiepin-2- and -9-carbonitrile and 4,10-dihydrothieno[2,3-c]-1-benzothiepin-6-carbonitrile; Antidepressants with a new activity profile
Authors: Šindelář Karel , Holubek Jiří , Matoušová Oluše , Svátek Emil , Valchář Martin , Dlabač Antonín , Dlohožková Nataša , Hrubantová Marta , Protiva Miroslav
Published: June 2010

Starting from the bromo ketones VIIc, XIII, and XXIV and proceeding via the alcohols VIIIc, IXc, XIV, XVII, and XXVI, the olefinic compounds IIc (+ VI), Xc (+XI), XVc and XIXc(+XXc), and the saturated compound XVIc were prepared. The pairs of geometrical isomers were separated by crystallization of salts and the individual compounds Iic, Xc, XVc, XVIc, XIXc, and XXc were transformed by treatment with cuprous cyanide in hexamethylphosphoric triamide to the corresponding cyano compounds IIb, Xb, XVb, XVIb, XIXb, and XXb. Compound IIb was synthesized also from the ketone VIIc via the cyano ketone VIIb and the cyano carbinol VIIIb. The secondary amine IIIb was prepared from IIc by partial demethylation with ethyl chloroformate, the following hydrolysis to IIIc, protection of NH group with butyrolactone, the following treatment with cuprous cyanide, and deprotection by mild hydrolysis. The title compounds, which are the cyano analogues of antidepressants of the prothiadene series, showed in pharmacological and biochemical tests properties of potential antidepressants and more or less selective inhibitors of the 5-hydroxytryptamine uptake in the rat brain; at the same time they are rather strong central cholinolytics.
Synthesis of (2-(phenylthio)phenyl)acetamidines and related amidoximes as potential antidepressants
Authors: Šindelář Karel , Šedivý Zdeněk , Hrubantová Marta , Valchář Martin , Metyšová Jiřina , Protiva Miroslav
Published: June 2010

Reactions of ethyl(2-(phenylthio)phenyl)acetimidate (X) hydrochloride with ammonia and the corresponding amines resulted in amidines V-X. Heating (2-(phenylthio)phenyl)acetonitrile with 2-aminoethylammonium toluene-4-sulfonate led to the 2-imidazoline XI. Reactions of (2-(phenylthio)phenyl)acetonitrile and the lower homologue with hydroxylamine gave the amidoximes XIII and XV; XIII was oxidized to the sulfoxide XIV. Compounds VII, XI, and XIII showed some antireserpine activity which indicates thymoleptic and antidepressant potentiality. On the other hand, none of the compounds tested did show any noteworthy affinity to the [3H]imipramine and [3H]desipramine binding sites in the rat hypothalamus.
Sequential oligopeptides containing lysene: Synthesis, circular dichroism, conformation and complexes with DNA
Authors: Votavová Hana , Pírková Jana , Gut Vladimír , Bláha Karel
Published: June 2010

Oligomeric (Lys-Ala-Ala)1-5 and (Lys-Leu-Ala)1-4 were synthesized by fragment condensation in solution, (Lys-Ala-Ala)10Ape was obtained by stepwise synthesis from the tripeptide monomer on a polymeric carrier. Conformation of the compounds in water, aqueous methanol and trifluoroethanol was studied by CD spectroscopy. The dimer and trimer in both the structural series show no signs of α-helix formation. The higher oligopeptides exist in random conformation in aqueous solutions, whereas in the presence of alcohols they are partly in the α-helical conformation, depending on the chain length and the character and concentration of the alcohol. However, the ability of α-helix formation is substantially lower even for the studied decamer than for polytripeptides of DP ~30 and higher. According to the CD spectra, the conformational changes resulting from interaction of the oligopeptides with DNA are generally small for both components. The changes of DNA structure may be interpreted as winding of the double helix. The oligopeptide conformation is very little affected by the complexation and is invariably random, contrary to that of the corresponding polypeptides which in complexes with DNA are at least partially α-helical.
Properties of supported rhodium catalysts for steam dealkylation of toluene
Authors: Zun Ro Yong , Davidová Helena , Polednová Jaroslava , Jirátová Květa , Schneider Petr
Published: June 2010

The effect of modification of γ-aluminia support by Cr2O3 on physical and catalytical properties of supported rhodium catalysts was investigated. Various techniques were used for characterization of catalysts: porosimetry, diffusion and permeation measurements, determination of surface OH groups, temperature-programmed reduction and catalytic behaviour in steam dealkylation of toluene. Using the transport parameters determined for pelleted catalysts the effect of internal diffusion on the reaction was predicted and compared with experiments.
Polarographic study of the mixed complexes of Cd(II) with oxalate and malonate ions
Authors: Rodríguez-Placeres Cesar , Ruiz-Cabrera Graciliano , Alloza Ana , Arévalo Agustin
Published: June 2010

The coordinated mixed Cd(II)-oxalate-malonate system has been polarographically studied in aqueous medium. The ionic strength has been maintained constant at μ = 1.0 mol l-1 by using NaClO4. The overall stability constants, determined by using the Schaap and McMasters method, for the coordinated species [Cd(ox)(mal)]2-, [Cd(ox)(mal)2]4- and [Cd(ox)2(mal)]4- are respectively β11 = 1.3 . 104 l2 mol-2, β12 = 5.0 . 104 l3 mol-3 and β21 = 8.7 . 104 l3 mol-3. The various coordination equilibria are discussed on the basis of statistical aspects.
Hydroxyethyliminodiacetic acid in the isotachophoretic separation of alkali cations
Authors: Valášková Iva , Zelenský Imrich , Zelenská Viera , Komarnicki Alexander , Kaniansky Dušan
Published: June 2010

N-hydroxyethyliminodiacetic acid (HIDA) has been used for the optimization of the isotachophoretic separation of alkali and alkaline earth metal cations. The required separation effect appears at the leading-electrolyte pH = 6-7. The separation of K+, Na+, Li+, Ba2+, Sr2+, Ca2+, and Mg2+ has been achieved using HIDA as the complexing co-counterion. In the dependence on the leading-electrolyte pH and on the HIDA concentration in it various migration sequences can be achieved in the isotachophoretic steady-state. Alkali metal cations present in the model mixtures were determined in the concentration range (1-125) . 10-5 mol l-1 with the relative standard deviation that was in most cases less than 1%. Detection limits for individual ions (for the injected sample volume of 25μl) were within the limits of (6.4-18). 10-6mol l-1. The separation of the alkali metals in mineral and drinking water and in the lyophilized blood demonstrate the practical use of the agent under study in the ITP analysis
Chelating equilibria of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and 4-(2-pyridylazo)resorcinol with La(III) ions
Authors: Gladilovich Dimitrii Borisovich , Kubáň Vlastimil , Havel Josef
Published: June 2010

2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol (BrPADAP) with lanthanum(III) ions in 50% (v/v) aqueous ethanol or 30-50% (v/v) aqueous dimethylformamide (DMF) forms unprotonated chelates ML and ML2 characterized by a double absorption band with maxima at 550 and 570 nm. The ML2 species is rather unstable, hydrolyzing readily to the M(OH)L chelate, which exhibits an absorption maximum at 570 nm. The molar absorptivities of the ML, ML2, and M(OH)L species, lying in the regions of 5.3-6.5, 7.0-7.2, and 6.5-7.2 m2 mmol-1, respectively, depend on the kind and fraction of the organic component in the solvent. The conditional equilibrium constants (-log βpqr = 3.3-4.0, 12.2-12.5, and 7.8-8.2, respectively) decrease with increasing fraction of the organic solvent; in systems with high proportions of ethanol orDMF, the formation of higher species is greatly suppressed. 4-(2-Pyridylazo)resorcinol (PAR) with La(III) in acid aqueous solutions forms the MLH and ML species with absorption maxima at 490 and 506 nm, respectively ( ε = 1.2 and 2.5 m2 mmol-1, respectively) and with conditional equilibrium constants –log βpqr = -3.4 and 3.5, respectively. In alkaline solutions with excess PAR, the ML2 species with the absorption maximum at 509 mn (ε = 4.6 m2 mmol-1) and conditional equilibrium constant –log βpqr = 8.1 is formed. This chelate hydrolyses readily forming the M(OH)L species and other hydrolysis products. The ML2 species of the two reagents, forming in ammoniacal buffer at pH 9.0 – 9.5 (PAR) and 8.2 – 8.4 (BrPADAP), can be used for a sensitive (ε = 3.8 and 6.1 m2 mmol-1, respectively) post-column derivatization of lanthanoids after their separation by IEC or HPLC or for their FIA determination.
Multicomponent determination by flow injection analysis using PU 4021 diode array detector. A direct determination of lanthanoids
Authors: Kubáň Vlastimil , Doležel Petr
Published: June 2010

Flow injection analysis (FIA) using a multichannel UV-VIS diode array detector enables several components with sufficiently separate absorption bands to be determined simultaneously. The effects of the basic parameters of the FIA apparatus (geometry, flow rates, etc.), error of measurement of the analytical signal, mutual interactions between the components to be determined, and the data handling procedure on the accuracy and precision of the calculated concentrations of the components are demonstrated on a model case of binary and ternary mixtures of Cu(II), Ni(II), Co(II), and U(VI). The majority and minority components can be determined with relative errors of 1-3% and 2-20%, respectively, over the concentration region of 2 to 200 mmol l-1 at concentration ratios from 1:1 to 50:1. The method has been applied to a simultaneous determination of Pr(III), Sm(III), and Nd(III) in oxidic concentrates of rare earths over the region of 1 – 20 mg ml-1 at concentration ratios down to 1:10 with relative errors not exceeding 5%.
The coordination compounds of nickel with glycine and with an N-N ligand
Authors: Březina František , Šindelář Zdeněk , Kameníček Jiří , Lasovský Jan
Published: June 2010

The compounds [Ni(Gly)2N-N].nH2O (n = 1, 2; Gly = glycine anion; N-N – ethylenediamine 1,10-phenanthroline, α,α’-bipyridyl) and K[Ni(Gly)3].3H2O were prepared. On the basis of their magnetochemical and spectral properties, the compounds obtained can be characterized as octahedral nickel(II) complexes. Cyclic voltammetry was employed to study the redox properties of selected compounds and possible electrochemical and chemical oxidation were studied. The results obtained permitted comparison with the properties of nickel(II) complexes with dipeptides or tripeptides as ligands.
13C and 119Sn NMR evidence of the presence and extent of σ-π conjugation in some benzyltin compounds and their complexes
Authors: Holeček Jaroslav , Lyčka Antonín , Handlíř Karel , Nádvorník Milan
Published: June 2010

The 13C and 119Sn NMR spectroscopy has been used to study the compounds types (C6H5CH2)4-nSn(CH3)n and (C6H5CH2)4-nSnCln (n = 0 - 3) in media of non-coordinating (deuteriochloroform) and coordinating (hexadeuteriomethyl sulphoxide) solvents. The analysis of the NMR data has confirmed the presence and established the relative extent of participation of the σ-π conjugative connection of the polarized σ(Sn-C) bond with the adjacent π electronic system of the aromatic ring in the Sn-CH2-C6H5 grouping. The extent of σ-π conjugation decreases with decreasing number of methyl groups in the compounds (C6H5CH2)4-nSn(CH3)n and with increasing number of chlorine atoms in the compounds (C6H5CH2)4-nSnCln and with increasing coordination number of the central tin atom in the complexes of the compounds (C6H5CH2)4-nSnCln.x(C2H3)2SO.
17O and 13C NMR spectra of some geminal diacetates
Authors: Lyčka Antonín , Jirman Josef , Holeček Jaroslav
Published: June 2010

The 17O and 13C NMR spectra of eight geminal diacetates RCH(O(CO)CH3)2 derived from simple aldehydes have been measured. In contrast to the dicarboxylates R1R2E(O(CO)R3)2, where E = Si, Ge, or Sn, whose 17O NMR spectra only contain a single signal, and, on the other hand, in accordance with organic carboxylic esters, the 17O NMR spectra of the compound group studied always exhibit two well-resolved signals with the chemical shifts δ(17O) in the regions of 183-219 ppm and 369-381 ppm for the oxygen atoms in the groups C-O and C=O, respectively.
Synthesis and cyclization of some N-oxides of 2-pyridylhydrazones of mesoxalic acid derivatives
Authors: Slouka Jan , Bekárek Vojtěch
Published: June 2010

Coupling of diazotized 2-aminopyridine-1-oxide with ethyl cyanoacetylcarbamate, cyanoacetamide, malononitrile, and 2-benzimidazolylacetonitrile in an acid medium afforded N-oxides of the corresponding 2-pyridylhydrazones Ia-Id, which also exist in the N-hydroxyazine tautomeric forms IIa-IId as confirmed by IR spectroscopy. Hydrazone Ia was thermally cyclized to give 2-(pyridine-1-oxide-2-yl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (IIIa) which was converted into the corresponding thioamide IIIb, acid IIIc, and amidoxime IIId.
Synthesis of juvabione analogues
Authors: Mane Ramchandra B. , Desai Uday V. , Hebbalkar Geeta D.
Published: June 2010

Alkylation of various β-ketoesters IIIa - d with bis(p-methoxycarbonylphenyl)bromomethane (II) and bis(p-chlorophenyl)bromomethane (VI) followed by cleavage of ethoxycarbonyl group or hydrolysis and esterification gave methoxycarbonylphenyl and chlorophenyl analogues of ar-juvabione, respectively. Condensation of bis(p-methoxycarbonylphenyl)methanol (IX) with isovaleryl and trichloroacetyl chloride gave isovalerate X and trichloroacetate XI, respectively, while the condensation of bis(p-chlorophenyl)methanol (XII) with isovaleryl chloride and citronellyl bromide yielded isovalerate XIII and citronellyl ether XIV, respectively. The methoxycarbonylation of aryl-alkyl ketones XVa - d with oxalyl chloride and treatment with methanol furnished various ar-juvabione analogues XVIa - d. The compounds Vb, Vc, Vd, XVIb, and XVIc showed high activity against Dysdercus koenigii at 1μg concentration.
On the geometry of d-orbitals: W (001) surface
Authors: Pick Štěpán
Published: June 2010

Low-order moment analysis of the W (001) surface reconstruction leads to the following conclusions: 1) The d-orbitals participate in the reconstruction-induced surface-surface coupling, the effect being most pronounced for the x2 - y2 orbital. 2) A non-negligible surface-bulk coupling exists and it is due to the (x - y) z orbital. An additional mechanism favouring the zig-zag mode is suggested.