Preparation of small size palladium nanoparticles by picosecond laser ablation and control of metal concentration in the colloid.

We assessed a method for the preparation of small, highly stable and unprotected Pd nanoparticles by picosecond laser ablation in 2-propanol. The nanoparticles can be extracted from 2-propanol by centrifugation and redispersed in water, where a strongly negative ζ-potential assures long term stability. The proposed procedure permits reduction of particle size down to 1.6nm and optimization of the Pd(0):Pd(II) ratio which, in the best cases, was of the order of 6:1. The increase of this ratio with ablation times has been correlated to the high temperature conversion of PdO to metallic Pd by a simple theoretical model. A study of the relationship between colloid absorption at 400nm and Pd concentration permitted the role of PdO in the determination of the UV-vis spectra to be clarified and the limits of the Mie theory for the evaluation of colloid concentration to be established. The absorption at 400nm can be used as a fast method to estimate the Pd content in the colloids, provided that a calibration of the ablation process is preliminarily performed.

Chiral/ring closed vs. achiral/open chain triazine-based organogelators: induction and amplification of supramolecular chirality in organic gels.

The purpose of this study is to compare the gelling behavior of two molecules: a chiral compound and its achiral counterpart. The chiral partner is characterized by a rigid, chiral pyrrolidine nucleus, while the achiral one contains a flexible diethanolamine moiety. The chiral compound is an already known good organogelator, but also the achiral compound shows remarkable gelling properties. Very interestingly, a small fraction of the chiral compound induces chirality and strong CD effects in its aggregates with the achiral one. The observed chirality amplification corresponds to a peculiar sergeant-and-soldier effect. Molecular modelling and CD calculations suggested a model for the supramolecular assembly of hetero-aggregates that fits the experimental data.

[Magnetic resonance with an endorectal coil and a fast spin echo sequence in the staging of prostatic carcinoma. The correlation with histopathological data]. / Risonanza Magnetica con bobina endorettale e sequenza Fast Spin Echo nella stadiazione del carcinoma prostatico. Correlazione con i dati istopatologici.

INTRODUCTION: We investigated the accuracy of endorectal coil Magnetic Resonance Imaging (MRI) and Fast Spin Echo (FSE) technique in staging prostate cancer. MATERIAL AND METHODS: MRI was performed in 70 patients with biopsy proved prostatic cancer. A total of 33 patients subsequently underwent radical prostatectomy. T2-weighted FSE sequences (TR 3400-4100, TE 120, Echo train length 13) were acquired in all patients. Axial, sagittal and coronal 4-5 mm images were obtained with 13-14 cm field of view and 256 x 256 matrix. Additional T1-weighted spin echo images were acquired in 9 patients. Lesion staging on MR images was performed according to the American Urological System. MR data were compared with the pathologic findings of whole-mount sections of the surgical specimens. RESULTS: Overall accuracy for endorectal coil MR imaging was 60%; ten cases were underestimated and 3 cases were overestimated. The sensitivity and the specificity of endorectal coil MRI in diagnosing capsular penetration were 77% and 81%, respectively. Seminal vesicle invasion was detected with 87% sensitivity and 96% specificity. CONCLUSIONS: Endorectal coil MRI provides a more accurate preoperative local staging.

[Evaluation of total and inflated lung volumes by a quantitative study using computerized tomography in patients with acute noncardiogenic pulmonary edema (ARDS)]. / Valutazione dei volumi polmonari totali e aereati mediante lo studio quantitativo con tomografia computerizzata nei pazienti con edema polmonare acuto non cardiogeno (ARDS).

Our study was aimed at developing a method to assess lung volumes and relative percentages of well-inflated lung parenchyma in Adult Respiratory Distress Syndrome (ARDS) patients by processing conventional CT examinations of the lung and at investigating the prognostic value of CT findings. Fourteen patients (5 women and 9 men, age range: 35-79 years) admitted to the intensive care unit January, 1992, to June, 1994, because of severe ARDS, and with lung injury scores exceeding 2.5, were submitted to CT. A homologous group of 14 patients matched for sex and age and with normal lungs was examined as a control group to investigate the accuracy of our method. Two examinations were obtained in 7 of 14 ARDS patients; the trend of lung volumes and of the relative rates of well-inflated parenchyma could thus be calculated. During the examination, we maintained in all ARDS patients the same ventilatory pattern used in the intensive care unit. Consequently, in 18/21 examinations scans and respiratory phases were not correlated. In the control group no statistically significant differences were observed between the scans obtained with (inspiratory apnea) and without coordination with the respiratory phase. As for lung volumes, our results in normal subjects showed a good correlation with normal spirometric data. In ARDS patients lung volumes, although reduced, did not correlate with prognosis. As for the percentage of well-inflated parenchyma in ARDS patients, we observed a good correlation with prognosis in the patients submitted to two examinations and, in all patients, a good correlation with D(A-a)O2 index (p < 0.05), PaO2/FiO2 index (p < 0.005) and with the rate of arteriovenous shunt (p < 0.001). In conclusion, our results show that CT of the lung is a reliable and repeatable method for the functional assessment of the lung in ARDS patients.

[Magnetic resonance with endorectal coil in the locoregional staging of rectal carcinoma]. / La risonanza magnetica con bobina endorettale nella stadiazione loco-regionale del carcinoma del retto.

The accurate locoregional staging of rectal cancer is important in choosing and planning therapy. The diagnostic contribution of endorectal ultrasonography and of Computed Tomography is well known because both methods have been widely used in the last ten years. More recently, Magnetic Resonance Imaging (MRI) has been introduced in the preoperative staging of rectal cancer: most interestingly, in the last three years endorectal surface coils have become available as a clinical device. February through November, 1994, twenty patients affected with rectal carcinoma were examined with endorectal MRI. In order to assess their accuracy, MR staging results were compared with pathologic findings. MRI was performed with an 0.5 T system equipped with an endorectal surface coil. In all cases T2-weighted turbo spin-echo sequences were performed on axial and sagittal or coronal planes. Rectal wall layers were reliably demonstrated in all patients. The comparison with pathologic findings showed 78.9% MR accuracy in assessing tumor infiltration depth. In addition, the study of perirectal lymph nodes showed 83.2% MR sensitivity and 53.8% MR specificity. The high resolution images obtained using endorectal surface coils and the well-known panoramic capabilities of this method reveal MR potentials in rectal carcinoma staging.

[CT-guided thoracic biopsy. Personal experience with DBNH Haaga 20 G needles]. / Biopsia toracica TC-guidata. Esperienza personale con ago tipo DBNH 20 G.

CT-guided fine-needle biopsy of the chest is nowadays a conventional diagnostic procedure, which can be furtherly improved so as to increase its diagnostic sensitivity and to reduce complications. We studied a series of possible improvements over a 2-year period (1990-1992). In our radiology department 164 CT-guided biopsies were performed in 130 men and 34 women. DBNH Haaga 20-G (15 cm) needles (Cook, Denmark) were used. This kind of needle is a coaxial cutting-edge needle used for simultaneous cytological and histological sampling. Exams were performed with a Philip Tomoscanner CX-S (scanning time: 2.8 seconds). Of 164 tissue samples, 153 (93.4%) were adequate for histological diagnosis. As for suspected neoplastic disease, our results demonstrated 108 true positives, 27 true negatives, 18 false negatives and no false positive. Sensitivity, specificity and diagnostic accuracy were 85.7%, 100% and 88.2%, respectively. In 24 cases there were minor complications--i.e., 5 cases of parenchymal hemorrhage and 19 cases of minor pneumothorax. In one case only there was major pneumothorax which required surgical drainage. On the basis of our experience, we suggest the use of such coaxial catheters as the DBNH Haaga type for the collection of both histological and cytological material because this needle reduces the need for repeated invasive and potentially dangerous maneuvers.

[Ultrasonography in the diagnosis of chronic inflammatory intestinal disease]. / L'ecotomografia nella diagnosi della malattia infiammatoria cronica intestinale.

The accuracy of ultrasonography (US) in diagnosing active inflammatory bowel disease (IBD) is assessed on the basis of a randomized prospective study of 61 patients. Twenty-six of the patients were affected with Crohn's disease (CD) and 12 with ulcerative colitis, while the remaining 23 patients were control subjects with no specific chronic IBD. The US signs considered as significant for active CD and UC were: --visualization of a typical target image, that is a hyperechoic center corresponding to luminal bowel content, surrounded by a hypoechoic ring corresponding to loop walls; --at least 2 of the following: solid abdominal mass, distended loops, luminal narrowing, reduced peristalsis, stiff loops, and accumulation of fluid between the loops. US sensitivity and specificity for CD were 77% and 95.6%, respectively. As for UC, no significant results were obtained. In our experience, US is a reliable method for detecting alterations and, especially, complications typical of CD in its active phase. Considering the young age of the patients affected with CD and the number of exams they must undergo, US is considered as a useful tool in disease follow-up.