Predicted binding rate of new cephalosporin antibiotics by a 3D-QSAR method: a new approach

Abstract  

Antibiotics are chemotherapeutic agents with activity against microorganisms, for example bacteria, fungi, or protozoa, used for the treatment of many types of diseases. Binding of antibiotics to serum proteins in human plasma is a major determinant of their pharmacodynamic and pharmacokinetic behavior and, consequently, can affect their systemic distribution in the body. Here, the predicted binding rates of ceftazidime and 13 other pharmacological agents classified as antibiotics to plasma proteins (percentage fraction bound; PFB) were evaluated by use of 3D-QSAR models. We attempted to establish the contribution of hydrogen bond donor/acceptor and hydrophobic properties supplied by electrostatic fields to the PFB. Significant cross-validated correlation q ² (0.5–0.7) and the fitted correlation r ² (0.7–0.97) coefficients revealed that these models have reasonable power to predict the design 19 new antibiotics using ceftazidime as template, these compounds being our suggestion for further studies.     

Deposition of biopolymer thin films by matrix assisted pulsed laser evaporation

We report on the successful deposition of high quality type I fibrilar collagen thin films by Matrix assisted pulsed laser evaporation (MAPLE). Thin films deposition was performed in a N₂ ambient (20 Pa) using a KrF* laser source (=248 nm,20 ns) operated at a repetition rate of 3 Hz, the incident laser energy at a value within the range (20-35)mJ , and the laser spot area was (3.5-18.5)±0.1 mm². The collagen films were deposited on double face polished 100 single crystalline Si wafers and characterized by Fourier transform infrared spectroscopy, atomic force microscopy and high-resolution transmission electron microscopy. We demonstrate that our thin films are composed of collagen, with no impurities and the roughness can be controlled by the deposition conditions. PACS 52.38.Mf; 82.35.Pq; 83.80.Lz     

Investigation of lifetimes in dipole bands of 141Eu

Lifetimes have been measured for dipole bands in ¹⁴¹Eu using DSAM. The deduced B(M1) and B(E2) values as well as B(M1)/B(E2) ratios are compared with calculations in the framework of the TAC (Tilted Axis Cranking) and SPAC (Shears mechanism with Principal Axis Cranking) models. The dipole bands can be interpreted as magnetic rotational bands.Received: 6 April 2004, Revised: 14 May 2004, Published online: 13 July 2004PACS: 21.10.-k Properties of nuclei; nuclear energy levels - 21.10.Re Collective levels - 21.10.Tg Lifetimes - 27.60. + j      

Delayed crossing in the \pi h_{9/2} 1/2-[541] band of 173 Lu

High-spin states in the odd-proton nucleus ¹⁷³Lu have been populated in a ¹⁷⁰Er(⁷Li,4n) reaction and the emitted -radiation was detected with the GASP array. The favoured and unfavoured sequences of the band have been considerably extended. The favoured sequence does not show any indication of a band crossing up to a rotational frequency of 0.45 MeV. This is the largest crossing frequency ever observed for 1/2^- [541] bands of odd-proton nuclei with and . Previous Cranked Shell Model (CSM) calculations underestimate the crossing frequency by 100 keV.Received: 19 May 2003, Published online: 11 November 2003PACS: 21.10.-k Properties of nuclei; nuclear energy levels - 21.10.Re Collective levels - 23.20.Lv transitions and level energies - 27.70. + q      

Structural and optical characterization of undoped, doped, and clustered ZnO thin films obtained by PLD for gas sensing applications

The synthesis by pulsed laser deposition technique of zinc oxide thin films suitable for gas sensing applications is herein reported. The ZnO targets were irradiated by an UV KrF^* (λ = 248 nm, τ_FWHM ∼7 ns) excimer laser source, operated at 2.8 J/cm² incident fluence value, whilst the substrates consisted of SiO₂(0 0 1) wafers heated at 150 °C during the thin films growth process. The experiments were performed in an oxygen dynamic pressure of 10 Pa. Structural and optical properties of the thin films were investigated. The obtained results have demonstrated that the films are c-axis oriented. Their average transmission in the visible-infrared spectral region was found to be about 85%. The equivalent refractive indexes and extinction coefficients were very close to those of the tabulated reference values. Doping with 0.5% Au and coating with 100 pulses of Au clusters caused but a very slight decrease (with a few percent) of both transmission and refractive index values. The coatings with the most appropriate optical properties as waveguides have been selected and their behavior was tested for butane sensing.     

Polycaprolactone biopolymer thin films obtained by matrix assisted pulsed laser evaporation

We report the successful deposition of polycaprolactone polymer by MAPLE using a KrF* excimer laser (λ = 248 nm, τ = 7 ns). According to FTIR spectra the deposited films have similar chemical structure to the dropcast material. The fluence plays a key role in optimizing the performances of MAPLE-synthesized polycaprolactone structures. We demonstrated that MAPLE allows for controlling the morphology of films to the level required in targeted drug delivery of pharmacologic agents.     

Matrix assisted pulsed laser evaporation of poly(d,l-lactide) thin films for controlled-release drug systems

We report the successful deposition of the porous polymer poly(d,l-lactide) by matrix assisted pulsed laser evaporation (MAPLE) using a KrF* excimer laser (248 nm, τ = 7 ns) operated at 2 Hz repetition rate. The chemical structure of the starting materials was preserved in the resulting thin films. Fluence played a key role in optimizing our depositions of the polymer. We demonstrated MAPLE was able to improve current approaches to grow high quality thin films of poly(d,l-lactide), including a porosity control highly required in targeted drug delivery.     

Thermal fields in laser–multi-layer structures interaction

In the present paper, we are dealing with the thermal fields for laser–periodic multilayer structures interaction. Our point of view is originally that we consider any order transverse laser beams, like heating sources. We consider that the laser beam acts in IR (Nd:YAG or CO₂ laser beam) and it is in one transverse mode or in only a few decoupled modes. In order to solve this problem, we will use the Green function method. Specific results are presented for a laser beam (Nd:YAG laser) operating in the mode TEM₀₁ and a two-layer structure.     

Structural characterization of AlN films synthesized by pulsed laser deposition

We obtained AlN thin films by pulsed laser deposition (PLD) from a polycrystalline AlN target using a pulsed KrF* excimer laser source (248 nm, 25 ns, intensity of ∼4 × 10⁸ W/cm², repetition rate 3 Hz, 10 J/cm² laser fluence). The target-Si substrate distance was 5 cm. Films were grown either in vacuum (10⁻⁴ Pa residual pressure) or in nitrogen at a dynamic pressure of 0.1 and 10 Pa, using a total of 20,000 subsequent pulses. The films structure was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and spectral ellipsometry (SE). Our TEM and XRD studies showed a strong dependence of the film structure on the nitrogen content in the ambient gas. The films deposited in vacuum exhibited a high quality polycrystalline structure with a hexagonal phase. The crystallite growth proceeds along the c-axis, perpendicular to the substrate surface, resulting in a columnar and strongly textured structure. The films grown at low nitrogen pressure (0.1 Pa) were amorphous as seen by TEM and XRD, but SE data analysis revealed ∼1.7 vol.% crystallites embedded in the amorphous AlN matrix. Increasing the nitrogen pressure to 10 Pa promotes the formation of cubic (≤10 nm) crystallites as seen by TEM but their density was still low to be detected by XRD. SE data analysis confirmed the results obtained from the TEM and XRD observations.     

MAPLE deposition of Mn(III) metalloporphyrin thin films: Structural, topographical and electrochemical investigations

We report the deposition by MAPLE of metallized nanostructured (5,10,15,20-tetraphenyl)porphinato manganese(III) chloride thin films onto gold screen-printed electrodes, or 〈1 1 1〉 Si substrates. The deposited nanostructures were characterized by atomic force microscopy and exhibited globular structures with average diameters decreasing with laser fluence. Raman spectroscopy showed that no major decomposition appeared. We have investigated the Mn(III)-metalloporphyrin thin films by cyclic voltammetry in order to evaluate the potential bio/chemosensing activity on dopamine neurotransmitter analyte. We have found that the manganese(III)-porphyrin is appropriate as a single mediator for dopamine sensing in the specific case of gold screen-printed electrodes.