Peter S. Conti

With the advent of a new generation of PET scanners that have introduced whole-body PET to the clinical setting, there is now more interest in developing protocols for the evaluation of both intracranial and somatic cancers. The value of PET in clinical oncology has been demonstrated with studies in a variety of cancers including colorectal carcinomas, lung tumors, head and neck tumors, primary and metastatic brain tumors, breast carcinoma, lymphoma, melanoma, bone cancers, and other soft-tissue cancers. A summary of current clinical applications of PET in oncology is presented with special attention to colorectal, lung, and intracranial neoplasms since the majority of clinical trials have focused on these cancers. A variety of radiopharmaceuticals are described that are currently included in clinical tumor-imaging protocols, including metabolic substrates such as fluorine-18-fluorodeoxyglucose and carbon-11-methionine, and analogs of chemotherapeutic agents such as fluorine-18-fluorouracil and fluoroestradiol. An attempt is also made to include examples of clinical trials that demonstrate response to therapeutic intervention. The increasing number of oncologic PET studies reflects the growing interest in functional imaging in oncology.

Noninvasive visualization of cell adhesion molecule alpha(v)beta(3) integrin expression in vivo has been well studied by using the radionuclide imaging modalities in various preclinical tumor models. A literature survey indicated no previous use of cyanine dyes as contrast agents for in vivo optical detection of tumor integrin. Herein, we report the integrin receptor specificity of novel peptide-dye conjugate arginine-glycine-aspartic acid (RGD)-Cy5.5 as a contrast agent in vitro, in vivo, and ex vivo. The RGD-Cy5.5 exhibited intermediate affinity for alpha(v)beta(3) integrin (IC(50) = 58.1 +/- 5.6 nmol/L). The conjugate led to elevated cell-associated fluorescence on integrin-expressing tumor cells and endothelial cells and produced minimal cell fluorescence when coincubated with c(RGDyK). In vivo imaging with a prototype three-dimensional small-animal imaging system visualized subcutaneous U87MG glioblastoma xenograft with a broad range of concentrations of fluorescent probe administered via the tail vein. The intermediate dose (0.5 nmol) produces better tumor contrast than high dose (3 nmol) and low dose (0.1 nmol) during 30 minutes to 24 hours postinjection, because of partial self-inhibition of receptor-specific tumor uptake at high dose and the presence of significant amount of background fluorescence at low dose, respectively. The tumor contrast was also dependent on the mouse viewing angles. Tumor uptake of RGD-Cy5.5 was blocked by unlabeled c(RGDyK). This study suggests that the combination of the specificity of RGD peptide/integrin interaction with near-infrared fluorescence detection may be applied to noninvasive imaging of integrin expression and monitoring anti-integrin treatment efficacy providing near real-time measurements.

We present 2 μm (K band) spectra of 180 well-studied, optically visible, luminous stars. Most of the stars are of OB spectral type, but we have also included a number of Oe and Be stars, OBN and OBC stars, cool hypergiant stars, and high-mass X-ray binary stars. Our aim in studying normal OB stars is to develop an empirical relationship between 2 μm spectral features of these massive stars and their stellar temperature and luminosity. We find the system of lines between 2.0 and 2.2 μm is particularly good for differentiating the early- and mid-O type stars. In the late-O and early-B stars, differentiation becomes more difficult, as the features show only moderate changes. We have developed a spectral classification system for the K band to be used to estimate effective temperatures of 0 and early-B stars. We demonstrate that K-band spectroscopy is superior in estimating the temperature of hot, luminous stars than the traditional methods of using infrared or even optical photometric colors alone. The only requirements are that adequate resolution (R &gt; 1000) and signal-to-noise (S/N ∼70) be achieved. With our classification system, stars behind large amounts of visible extinction, such as in young, heavily reddened H II regions throughout our Galaxy, may be identified and studied for the first time through 2 μm spectroscopy. <P />Emission lines are commonly seen in the K-band spectra of supergiant stars, however, the OBN super-giants, which have a higher ratio of some processed materials at their surface, may be more likely to show line emission, especially the He I singlet transition at 2.058 μm. This has led us to propose an evolutionary scenario for some of the Galactic center He I emission-line stars, which evokes rotational mixing (Maeder 1987; Langer 1992) to explain both the strong line emission and high luminosity of these mysterious sources. <P />We have compared our spectroscopic database with the most recent stellar atmosphere models. We are encouraged by the good match between the model line profiles at 2 μm of Schaerer et al. (1996b) and those observed in OB stars. Finally, we include a thorough discussion of the observational and reduction methods employed to obtain the spectra shown in this atlas for the benefit of those wishing to obtain similar, classification-quality, near-infrared spectra.