Photo-activated raster scanning thermal imaging at sub-diffraction resolution

Active thermal imaging is a valuable tool for the nondestructive characterization of the morphological properties and the functional state of biological tissues and synthetic materials. However, state-of-the-art techniques do not typically combine the required high spatial resolution over extended fields of view with the quantification of temperature variations. Here, we demonstrate quantitative far-infrared photo-thermal imaging at sub-diffraction resolution over millimeter-sized fields of view. Our approach combines the sample absorption of modulated raster-scanned laser light with the automated localization of the laser-induced temperature variations imaged by a thermal camera. With temperature increments ∼0.5-5 °C, we achieve a six-time gain with respect to our 350-μm diffraction-limited resolution with proof-of-principle experiments on synthetic samples. We finally demonstrate the biological relevance of sub-diffraction thermal imaging by retrieving temperature-based super-resolution maps of the distribution of Prussian blue nanocubes across explanted murine skin biopsies.

μMAPPS: a novel phasor approach to second harmonic analysis for in vitro-in vivo investigation of collagen microstructure

Second Harmonic Generation (SHG) is a label-free imaging method used to monitor collagen organization in tissues. Due to its sensitivity to the incident polarization, it provides microstructural information otherwise unreachable by other intensity based imaging methods. We develop and test a Microscopic Multiparametric Analysis by Phasor projection of Polarization-dependent SHG (μMAPPS) that maps the features of the collagen architecture in tissues at the micrometer scale. μMAPPS retrieves pixel-by-pixel the collagen fibrils anisotropy and orientation by operating directly on two coupled phasor spaces, avoiding direct fitting of the polarization dependent SHG signal. We apply μMAPPS to fixed tissue sections and to the study of the collagen microscopic organization in tumors ex-vivo and in-vivo. We develop a clustering algorithm to automatically group pixels with similar microstructural features. μMAPPS can perform fast analyses of tissues and opens to future applications for in-situ diagnosis of pathologies and diseases that could assist histo-pathological evaluation.

Quinoline-3-carboxamide containing sulfones as liver X receptor (LXR) agonists with binding selectivity for LXRbeta and low blood-brain penetration

A series of quinoline-3-carboxamide containing sulfones was prepared and found to have good binding affinity for LXRbeta and moderate binding selectivity over LXRalpha. The 8-Cl quinoline analog 33 with a high TPSA score, displayed 34-fold binding selectivity for LXRbeta over LXRalpha (LXRbeta IC(50)=16nM), good activity for inducing ABCA1 gene expression in a THP macrophage cell line, desired weak potency in the LXRalpha Gal4 functional assay, and low blood-brain barrier penetration in rat.

Discovery and SAR of cinnolines/quinolines as liver X receptor (LXR) agonists with binding selectivity for LXRbeta

A series of cinnolines/quinolines was prepared and it was found that 4-phenyl-cinnoline/quinolines with either a 2',3' or 2',5'-disubstituted benzyloxy moiety or the 1-Me-7-indole methoxy moiety on the meta position of the 4-phenyl ring showed good binding selectivity for LXRbeta over LXRalpha. The LXRbeta binding selective modulators displayed good activity for inducing ABCA1 gene expression in J774 macrophage cell line and poor efficacy in the LXRalpha Gal4 functional assay. 26, 37 and 41 were examined for their ability to induce SREBP-1c gene expression in Huh-7 liver cell line and they were weak partial agonists.

Protonation and conformational dynamics of GFP mutants by two-photon excitation fluorescence correlation spectroscopy

GFP mutants are known to display fluorescence flickering, a process that occurs in a wide time range. Because serine 65, threonine 203, glutamate 222, and histidine 148 have been indicated as key residues in determining the GFP fluorescence photodynamics, we have focused here on the role of histidine 148 and glutamate 222 by studying the fluorescence dynamics of GFPmut2 (S65A, V68L, and S72A GFP) and its H148G (Mut2G) and E222Q (Mut2Q) mutants. Two relaxation components are found in the fluorescence autocorrelation functions of GFPmut2: a 10-100 micros pH-dependent component and a 100-500 micros laser-power-dependent component. The comparison of these three mutants shows that the mutation of histidine 148 to glycine induces a 3-fold increase in the protonation rate, thereby indicating that the protonation-deprotonation of the chromophore occurs via a proton exchange with the solution mediated by the histidine 148 residue. The power-dependent but pH-independent relaxation mode, which is not affected by the E222Q and H148G mutations, is due to an excited-state process that is probably related to conformational rearrangements of the chromophore after the photoexcitation, more than to the chromophore excited-state proton transfer.

Voltage regulation of fluorescence emission of single dyes bound to gold nanoparticles

An organic dye, SAMSA, bound to gold nanoparticles, displays random photoactivated fluorescence blinking whose rate depends on the size of the nanoparticles. We report experiments indicating that (1) the dye emission wavelength is red-shifted (10-30 nm) by applying an external low voltage (1-10 V) and that (2) the fluorescence emission of single dyes can be resonantly driven by tuning the alternating external bias frequency from 1 to 3 Hz, depending on the nanoparticle size. These properties appear highly valuable and promising for devising light emitting nanostructures.

Discovery of Phenyl Acetic Acid Substituted Quinolines as Novel Liver X Receptor Agonists for the Treatment of Atherosclerosis

A structure-based approach was used to optimize our new class of quinoline LXR modulators leading to phenyl acetic acid substituted quinolines 15 and 16. Both compounds displayed good binding affinity for LXRbeta and LXRalpha and were potent activators in LBD transactivation assays. The compounds also increased expression of ABCA1 and stimulated cholesterol efflux in THP-1 cells. Quinoline 16 showed good oral bioavailability and in vivo efficacy in a LDLr knockout mouse model for lesions.

Temporal myofascial flap in reconstructive surgery of the oral cavity

AIM

The temporal myofascial flap is a simple, rapid and reliable surgical method for immediate reconstruction of facial defects: indications in the light of modern anatomical knowledge and personal experience, with the accent on achieving an appropriate access route without damaging the facial nerve.

METHODS

Our series covers the period from January 1999 to December 2004, during which time myofascial flaps of temporal muscle were used for immediate reconstruction in 20 surgical oncological cases involving the face and neck.

RESULTS

Postoperative progress was regular; no lesions of the facial nerve were observed, nor any cases of flap necrosis, including partial. Epithelialisation could already be observed as early as 15 days postsurgery without skin grafting being employed.

CONCLUSIONS

Application of a Medpor prosthesis eliminates the only negative outcome from the aesthetic standpoint, related to harvesting the muscle from the fossa.

Treatment of lower lip cancer: an experience of 48 cases

The article reports results obtained in 48 cases of lower lip cancer. Tumor classified as T1 or T2, requiring a resection up to 60% of the lower lip, were treated with the stair-case technique. Nine patients were treated with the bilateral symmetrical stair-case technique since their lesions were located medially, while 23 were treated with the bilateral method using two asymmetrical flaps because their lesions were in paramedian position but larger than 2 cm. Ten patients required a unilateral flap. The cases classified as T3, in which the lesion required resection of more than 60% of the lip, were treated with the Bernard-Freeman-Fries technique.

Selective Fluorescence Recovery after Bleaching of Single E2GFP Proteins Induced by Two-Photon Excitation

We report the two-photon excitation and emission or a recently developed green fluorescent protein (GFP) mutant, E(2)GFP. Two main excitation bands are found at 780 and 870 nm. Blinking and irreversible and reversible bleaching were observed. Fluorescence blinking occurs in the millisecond range and has been ascribed to conversions between the neutral, anionic and dark zwitterionic states. Bleaching is observed after approximately 10 to 400 ms depending on the excitation power, and it is probably due to a conversion to a dark state. The striking feature of this GFP mutant is that the fluorescence can be recovered with very high efficiency only upon irradiation at 720 +/- 10 nm. This GFP mutant therefore seems promising as an almost permanent chromophore for two-photon excitation (TPE) microscopy or for applications in single-molecule memory arrays.

Rotational dynamics of curved DNA fragments studied by fluorescence polarization anisotropy

The rotational dynamics of short DNA fragments with or without intrinsic curvature were studied using time-resolved phase fluorimetry of intercalated ethidium with detection of the anisotropy. Parameters determined were the spinning diffusion coefficient of the DNA fragments about the long axis and the zero-time ethidium fluorescence anisotropy. We find a significant decrease in the spinning diffusion coefficient for all curved fragments compared to the straight controls. This decrease is likewise evident in rotational diffusion coefficients computed from DNA structures obtained by a curvature prediction program for these sequences. Using a hinged-cylinder model, we can identify the change in rotational diffusion coefficient with a permanent bend of 13-16 degrees per helix turn for the sequences studied. Moreover, for some of the curved fragments an increased flexibility has to be assumed in addition to the permanent bend in order to explain the data.

New insight on beta-lactoglobulin binding sites by 1-anilinonaphthalene-8-sulfonate fluorescence decay

The fluorescence time decay parameters of the beta-lactoglobulin-1-anilinonaphthalene-8-sulfonate complex have been investigated under physical and chemical perturbations (2 < pH < 8 and added electrolyte 0 < NaCl < 0.5 M) to obtain new insight on the nature of the protein binding interactions. A double exponential decay of the bound probe lifetime has been confirmed by the presence of a longer component, 11 to 14.5 ns, and a shorter component, 2.5 to 3.5 ns. The two lifetimes are ascribed to different binding modes associated also with different exposure to the solvent; in particular, the longer component is attributed to binding inside the hydrophobic beta barrel, while a "surface" site is suggested for the shorter component. A detailed analysis of the lifetime fractional intensities correlates the binding constants with ionic strength and supports the presence of electrostatic effects at both sites. A Debye-Hückel approach, applied to extrapolate the electrostatic free energy contribution vs. pH at vanishing ionic strength, gives interesting clues on the effective charge felt by the ANS ligands in the proximity of each site. In particular, binding is found to parallel the aspartate and glutamate titrations between pH 3 and pH 4.5; the "surface" site mainly responds to the presence of these local titrating charges while the "internal" site more closely follows the overall protein net charge.

[Synovial chondromatosis of the temporomandibular joint]

Synovial chondromatosis is an uncommon monoarticular proliferative disease of the synovium characterized by loose bodies developed in the synovial membrane. The literature is reviewed and two cases of synovial chondromatosis of the temporomandibular joint characterized by swelling, pain and limitation of mandibular movement are reported. Radiographic evidence of loose bodies may or may not be present. Computed tomography (CT) or magnetic resonance (MR) might be helpful in the diagnosis of synovial chondromatosis. The treatment of choice of synovial chondromatosis is surgical and the loose bodies should be removed by arthrotomy with examination of the joint cavity. In our patients, no recurrence had occurred according to other authors' experience.

Evidence of heterogeneous 1-anilinonaphthalene-8-sulfonate binding to beta-lactoglobulin from fluorescence spectroscopy

Steady-state and dynamic fluorescence titrations show that: (a) the complex between beta-lactoglobulin (BLG) and 1-anilinonaphthalene-8-sulfonate (ANS) displays a heterogeneous equilibrium with large changes in the binding strength vs. pH and ion concentration; and (b) the fluorescence response of bound ANS reveals two separate lifetimes that suggest two different sites (or binding modes). While steady-state fluorescence titrations yield effective values of the binding constant and of the bound ANS quantum efficiency, it is shown that, by combining steady-state fluorescence and lifetime decay of ANS, it is possible to give quantitative estimates of the association constants for each site. When heading from the acid (pH approximately 2) to the native state (pH approximately 6) the main result is a very large reduction of the effective binding constant. This and the results of titrations vs. ionic strength suggest that electrostatic interactions are a major contribution to ANS binding to BLG.

Conformation of short DNA fragments by modulated fluorescence polarization anisotropy

The technique of fluorescence polarization anisotropy (FPA) decay of intercalated ethidium has been used to study DNA conformation and dynamics, which are being recognized as primary determinants in transcription control and other cellular processes. Frequency modulated FPA when applied to two DNA molecules, a "straight" 50 base-pairs duplex fragment, and a bent fragment of similar length, has yielded different rotational diffusion coefficients for the two fragments. The data have been processed with an analytical model and with Brownian dynamics simulations, obtaining a good fit and a quantitative agreement between the two models. Both analyses have confirmed that one fragment can be described as a straight cylinder, while the other fragment is bent, with an angle estimated to be 45 degrees +/- 3 degrees. FPA has proved to be very powerful in determining simple conformations of short DNA duplexes and also particularly apt to probe the dynamical features of DNA fragments where conventional methods are either too cumbersome or fail to give quantitative results. In addition, the ligand no longer behaves ideally due to its complex structure and charge distribution. Thus for the protein the slope is no longer related simply to the net ligand charge, and the PB model gives a much larger slope than the LL model.(ABSTRACT TRUNCATED AT 400 WORDS)

Influence of ligands on the fluorescence polarisation anisotropy of ethidium bound to DNA

The decay of the fluorescence polarisation anisotropy (FPA) of the ethidium-DNA complex has been measured by multifrequency phase fluorometry, in order to study the perturbations induced by the presence of different ligands on the torsional dynamics of DNA, a moderately flexible polymer that undergoes bending (flexure of the helix axis) and torsional (twisting of base pairs) motions. Two probes have been used together with ethidium: an intercalator, chloroquine, and a minor groove binding dye: hoechst 33258. Chloroquine is found to substantially modify the DNA torsional dynamics both in linear and in circularly closed DNAs only at high binding ratios, in agreement with previous reports [Wu et al. Biochem. 27 (1988) 8128]. The effective elastic constant becomes approximately three times larger when the dye/base pairs binding ratio is higher than 0.14. The minor groove ligand hoechst 33258, on the other hand, greatly increases the effective elastic constant to the point that at dye/base pairs ratios larger than 0.5, the effective elastic constant becomes stiffer by several orders of magnitude, suggesting a progressive hindering of internal motions. The results reported here show that DNA torsions are more effectively influenced by groove-binding molecules than by intercalators and it is expected that the large perturbation of the former ligand may be useful when describing the change in the dynamical properties induced by DNA binding proteins. FPA in the frequency domain, the technique adopted throughout this work, has proved to be very sensitive to changes of the elastic constant that describes DNA torsional dynamics. Several computer simulations performed in order to predict the FPA time decay of intercalated ethidium have led to good agreement with the observed results.

DNA torsional dynamics by multifrequency phase fluorometry

The time decay of the fluorescence polarization anisotropy of calf thymus DNA-ethidium complexes is obtained from measurements with sine-modulated excitation employing the so-called multifrequency phase fluorometry. A torsional dynamics model developed by J. M. Schurr [(1984) Chemical Physics, Vol. 84, pp. 71-96] and translated into the frequency domain is found here to describe accurately DNA-ethidium fluorescence data collected under modulated excitation. At a low dye/DNA ratio (1:400) the value of the DNA torsional constant (alpha = 4.63 +/- 0.2 10(-12) dyne cm) fitting the data agrees very well with the known values of alpha. When the measurements are extended to a higher ethidium/DNA ratio, energy transfer effects between intercalated dyes are observed. A theoretical prediction of the donor and acceptor dye contributions to the fluorescence polarization anisotropy is made here, taking into account also dye-dye distance distributions.

The pectoralis major myocutaneous flap. Experience in 100 consecutive cases

The authors have made a study of 100 consecutive cases in whom a pectoralis major myocutaneous flap was employed for reconstruction after surgical ablation of advanced malignant tumours in the head and neck. The results obtained show that primary healing took place in 74% of cases with a relatively low incidence of complications. The authors therefore confirm the reliability of the pectoralis major myocutaneous flap, which, owing to its rich blood supply, offers the possibility of providing large cutaneous islands, and its proximity to the site of ablation provides a simple and reliable method which may be used in the majority of cases of immediate or delayed reconstruction of the cervico-maxillo-facial area.

Total glossectomy without laryngectomy

When cancer of the tongue reaches a large size (T3, T4) it is almost impossible to treat it successfully with radiotherapy. The only therapeutic possibility in such cases is, therefore, total glossectomy. This may be effected without laryngectomy and with immediate reconstruction using musculo-cutaneous flaps. Such an operation allows total removal of the tumour and is followed by an acceptable though impaired functional result. Eight cases subjected to total glossectomy without laryngectomy are presented and aspects of ablative and reconstructive surgery are discussed. A report is made of postoperative complications and of functional rehabilitation: mastication is certainly impaired. However, swallowing is regained rapidly and phonation, although altered, is still comprehensible. An acceptable quality of life and good possibilities for a return to a working life result.

Temporary intranasal prosthesis for a surgical defect of septum and columella

A temporary intranasal prosthesis for the treatment of a surgical defect of the septum and columella after resection for a neoplasm has been described. The prosthesis is applied as soon as possible after surgery, which will limit complications during healing. Silicone elastomer is used because its softness does not produce decubitus ulcer, and it will accurately fit the surgical defect. The prosthesis can be relined easily during the postoperative period.

[Hearing changes in patients with cleft lip and palate: clinico-statistical contribution]

The otological complications which may occur in subjects with cleft lip and palate due to middle ear and tubal impairment related to velopharyngeal musculature are discussed. Three groups of patients aged 3-15 years have been submitted to clinical examination, audiometry and impedance measurement. In 2/3 of cases there was hearing impairment between 20-40 dB and 72% out of children younger than 8 years a pathological tymponometric curve was observed. These results confirm the positive relationship between cleft palate and hearing impairment and suggest that these children must be followed-up very carefully in oder to prevent middle ear and tubal alterations.