Michele Bello

Inhibition of Hepatocellular Carcinomas in vitro and Hepatic Metastases in vivo in Mice by the Histone Deacetylase Inhibitor HA-But

Purpose: The purpose is to evaluate the CD44-mediated cellular targeting of HA-But, a hyaluronic acid esterified with butyric acid (But) residues, to hepatocellular carcinoma cell lines in vitro and to hepatic tumor metastases in vivo. Experimental Design: In vitro, the CD44-dependent cytotoxicity in two human hepatocellular carcinoma cell lines (HepB3 and HepG2) with high and low CD44 expression was investigated; in vivo, the effect on liver metastases originating from intrasplenic implants of Lewis lung carcinoma (LL3) or B16-F10 melanoma in mice was compared with the pharmacokinetics of organ and tissue distribution using different routes of administration. Results: HepB3 and HepG2 cell lines showed different expression of CD44 (78 and 18%, respectively), which resulted in a CD44-dependent HA-But inhibitory effect as demonstrated also by the uptake analysis performed using radiolabeled HA-But (99mTc-HA-But). Pharmacokinetic studies showed different rates of 99mTc-HA-But distribution according to the route of administration (i.v., i.p., or s.c.): very fast (a few minutes) after i.v. treatment, with substantial accumulation in the liver and spleen; relatively slow after i.p. or s.c. treatment, with marked persistence of the drug at the site of injection. The effect of s.c. and i.p. treatment with HA-But on liver metastases originating from intrasplenic implants of LL3 carcinoma or B16-F10 melanoma (both CD44-positive: 68 and 87%, respectively), resulted in 87 and 100% metastases-free animals, respectively (regardless of the route of administration), and a significant prolongation of the life expectancy compared with control groups. Conclusions: HA-But tends to concentrate in the liver and spleen and appears to be a promising new drug for the treatment of intrahepatic tumor lesions.

Performance measurements of a high-spatial-resolution YAP camera

Physical properties of a position-sensitive camera for the analysis of biodistributions of gamma- and beta-emitting radiopharmaceuticals in small animals have been studied, in order to achieve optimal operating conditions. The camera consisted of a highly segmented yttrium-aluminate perovskite (YAP) scintillator, coupled to a position-sensitive photomultiplier. The energy resolution, the detection efficiency, the spatial resolution, the spatial linearity and the count-rate linearity of the YAP camera have been determined. Images related to initial activity levels and successive biodistribution evolution in mice organs are presented as an illustration of the camera performance.

Measuring the imaged-object distance with a stationary high-spatial-resolution scintillation camera.

A method to measure the detector-to-object distance from the images obtained with stationary high-spatial-resolution gamma-ray cameras for in vivo studies has been developed. It exploits the shift of the imaged object in the image plane, obtained at a certain tilt of the parallel-hole collimator. A linear dependence of the image displacement on the distance to the object has been measured using a high-spatial-resolution scintillation camera employing an yttrium-aluminium perovskite (YAP) scintillator. It is shown that the modified YAP camera can be used to obtain three-dimensional information without moving the camera or the object. The method could be applied in scintimammography and radioguided surgery, in lymphoscintigraphy, as well as in the analysis of the biodistribution of radiopharmaceuticals.

In-house cyclotron production of high-purity Tc-99m and Tc-99m radiopharmaceuticals

In the last years, the technology for producing the important medical radionuclide technetium-99m by cyclotrons has become sufficiently mature to justify its introduction as an alternative source of the starting precursor [99mTc][TcO4]- ubiquitously employed for the production of 99mTc-radiopharmaceuticals in hospitals. These technologies make use almost exclusively of the nuclear reaction 100Mo(p,2n)99mTc that allows direct production of Tc-99m. In this study, it is conjectured that this alternative production route will not replace the current supply chain based on the distribution of 99Mo/99mTc generators, but could become a convenient emergency source of Tc-99m only for in-house hospitals equipped with a conventional, low-energy, medical cyclotron. On this ground, an outline of the essential steps that should be implemented for setting up a hospital radiopharmacy aimed at the occasional production of Tc-99m by a small cyclotron is discussed. These include (1) target production, (2) irradiation conditions, (3) separation/purification procedures, (4) terminal sterilization, (5) quality control, and (6) Mo-100 recovery. To address these issues, a comprehensive technology for cyclotron-production of Tc-99m, developed at the Legnaro National Laboratories of the Italian National Institute of Nuclear Physics (LNL-INFN), will be used as a reference example.

Positioning accuracy and precision of a three-degrees-of-freedom manipulator guided by tilting-collimator scintillation camera

In our previous studies we have considered a possible use of a manipulator for biomedical applications guided by the so-called tilting-collimator (TC) scintillation gamma-ray camera. The imaged gamma-ray emitting object is localized exploiting our patented method to determine the camera-to-object distance using a TC camera (patent No RM 2006 A 000216, UIBM Roma). Thus the three coordinates of the object are obtained without moving either the camera or the object.

Localizing the Imaged-Object Position by a Stationary Position-Sensitive Scintillation Camera Using Tilted-Collimator Technique

A method to measure the detector-to-object distance from the images obtained with a stationary high-spatial-resolution gamma-ray camera for in-vivo small-object studies has been developed. It exploits the shift of the imaged object in the image plane, obtained for tilted positions of a parallel-hole collimator. In this way three-dimensional information about the object position can be obtained without moving either the camera or the object. The effectiveness of the method has already been tested for point-like gamma-ray emitting objects in our previous studies. In the present work we show the results of series of measurements conducted for three-dimensional small-size objects. Gamma-ray images from cavities filled with a solution of 99mTc at different depth position in tissue equivalent phantoms have been analyzed. A linear dependence of the image displacement on the object distance has been measured, using a scintillation camera employing an yttrium-aluminum perovskite (YAP) scintillator. A prototype of a computer-guided manipulator, designed for on-line operations such as e.g. needle biopsy, is presented. The instrument design and the preliminary results are discussed.

Radioisotopic purity and imaging properties of cyclotron-produced 99mTc using direct 100Mo(p,2n) reaction

Evaluation of the radioisotopic purity of technetium-99m (99mTc) produced in GBq amounts by proton bombardment of enriched molibdenum-100 (100Mo) metallic targets at low proton energies (i.e. within 15-20 MeV) is conducted. This energy range was chosen since it is easily achievable by many conventional medical cyclotrons already available in the nuclear medicine departments of hospitals. The main motivation for such a study is in the framework of the research activities at the international level that have been conducted over the last few years to develop alternative production routes for the most widespread radioisotope used in medical imaging. The analysis of technetium isotopes and isomeric states (9xTc) present in the pertechnetate saline Na99mTcO4 solutions, obtained after the extraction/purification procedure, reveals radionuclidic purity levels basically in compliance with the limits recently issued by European Pharmacopoeia 9.3 (2018 Sodium pertechnetate (99mTc) injection 4801-3). Moreover, the impact of 9xTc contaminant nuclides on the final image quality is thoroughly evaluated, analyzing the emitted high-energy gamma rays and their influence on the image quality. The spatial resolution of images from cyclotron-produced 99mTc acquired with a mini-gamma camera was determined and compared with that obtained using technetium-99m solutions eluted from standard 99Mo/99mTc generators. The effect of the increased image background contribution due to Compton-scattered higher-energy gamma rays (E γ   >  200 keV), which could cause image-contrast deterioration, was also studied. It is concluded that, due to the high radionuclidic purity of cyclotron-produced 99mTc using 100Mo(p,2n)99mTc reaction at a proton beam energy in the range 15.7-19.4 MeV, the resulting image properties are well comparable with those from the generator-eluted 99mTc.

Electronic setup for fluorescence emission measurements and long-time constant-temperature maintenance of Single-Walled Carbon Nano-Tubes in water solutions

Abstract In our previous research we have observed that the fluorescence emission from water solutions of Single-Walled Carbon Nano-Tubes (SWCNT), excited by a laser with a wavelength of 830nm, diminishes with the time. We have already proved that such a fading is a function of the storage time and the storage temperature. In order to study the emission of the SWCNT as a function of these two parameters we have designed and realized a special measurement compartment with a cuvette holder where the SWCNT solutions can be measured and stored at a fixed constant temperature for periods of time as long as several weeks. To maintain the measurement setup under a constant temperature we have designed special experimental setup based on two Peltier cells with electronic temperature control.

Feasibility tests of a dual modality system for imaging using gamma rays and NIR light

We are developing a dual system for small-animal imaging in multimodality studies, which consists of a highspatial resolution gamma-camera and a scanner for Near-Infra-Red (NIR) light. The gamma-camera is assembled from a position-sensitive photomultiplier and a scintillation-crystal with parallel-hole collimator. On the other hand, the NIR imaging is designed for near-object scanning, and features two operational modes: Transmission and Fluorescence. In the Transmission mode, the NIR light, coming from five different wavelength LEDs, crosses the sample and is subsequently measured by an array sensor. In the Fluorescence mode, the emission from nanoparticles, such as singlewalled carbon nanotubes (SWCNTs) administered in the imaged object, is excited using the laser. The gamma-camera energy and spatial resolutions have been measured. This latter has been assessed by using specially-designed phantoms like capillary tubes or volumes with cavities filled with a radioactive solution. The NIR-scanner spatial r...

Performance Analysis of Multi-Wavelength Transmission Scanner for Polarized NIR Light

A system for small-object imaging, comprising a multiple-wavelength scanner for Near Infra-Red (NIR) light is under development in the Laboratory of Radiopharmaceuticals and Molecular Imaging (LRMI) at the National Laboratories of Legnaro, INFN, Italy. The System performs scanning of biological objects using NIR light in the interval of 900nm − 1700nm. The scanned region is a rectangular with dimensions of 50mm × 80mm and is performed by consecutive positioning of InGaAs linear image sensor sliding close to the scanned object. The scanning is carried out in two different modes. The first mode is performed in transmitted linearly polarized NIR light using a set of five light emitting diodes with fixed wavelengths. The process of scanning is realized by a consecutive positioning of the NIR sensor and signal acquisition at the corresponding position. In the second scanning mode the fluorescence emission of nanoparticles such as single-walled carbon nanotubes (SWCNTs), administered in the imaged object, is excited by NIR lasers with different wavelengths. Spatial resolution of the system for transmitted linearly polarized NIR at five fixed wavelengths has been determined. Polarimetric measurements of some optically active sugars such as fructose and lactose were conducted at some fixed wavelengths in the range of 900–1200nm. The system sensitivity with respect to the concentrations of these agents has been estimated.