Positron emission tomography (PET) is an emerging clinical imaging technique that is facing the challenges of expansion in a period of imminent health care contraction and reform. Although PET began ...showing utility in clinical medicine in the mid-1980s 1, its proliferation into mainstream medical practice has not matched that of other new imaging technologies such as MR imaging. Many factors have contributed to this, including the changing health care economy, the high cost of PET, the length of time it takes to develop a PET facility, and its inherent complexity. In part because of the proliferation of the use of other technologies and the general explosion of costs, insurance carriers are now holding diagnostic techniques, including PET, to stricter standards of efficacy. New techniques must show improvement in long-term outcome of patients, a difficult task for diagnostic tools. In addition to these issues, PET is an expensive technology that requires highly trained multidisciplinary personnel. Questions have also been raised about the most appropriate mechanism for regulation of PET isotope preparation, leading to speculation about future regulatory requirements. The current pioneers of PET must meet these challenges in order for it to become a routine imaging technique. Because of its clinical value, PET will probably survive despite the challenges. For many reasons, though, not every hospital should necessarily develop PET services. Conversely, many hospitals without this technology should consider acquiring PET. The purpose of this article is to identify the financial, operational, and clinical challenges facing PET centers today, describe potential organizational configurations that may enable PET to survive in an antitechnology environment, and delineate which institutions should consider this new technology.
1-μm spectroscopy of normal OB stars Conti, Peter S.; Howarth, Ian D.
Monthly notices of the Royal Astronomical Society,
01/1999, Volume:
302, Issue:
1
Journal Article
Peer reviewed
We have obtained spectra of 70 normal OB stars in the near-IR I (1μm) band. The strongest features are those due to lines of the hydrogen Paschen series and neutral and ionized helium, which are, for ...the most part, in absorption. The information content in this spectral range is sufficient for only a rough classification of hot stars into ‘early O’, ‘late O’ and ‘B’ types. Curiously, the leading He i triplet line, He i λ1.0830 μm, is usually not detectable, although in a few stars it is in emission; its behaviour generally correlates with the leading helium singlet line, He i λ 2.058 μm. These two features appear to be present in emission only in stars with extremes of mass loss or wind extension.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The effects of UV light on hydrophilic polymers used as drug release modulators in matrix-tablets are evaluated. Three different polymers were chosen for this study: hydroxypropylmethyl cellulose ...(HPMC), polyethylene oxide (PEO) and polyvinyl alcohol (PVA). Diltiazem hydrocloride, a well-known photostable molecule, was chosen as model drug. When matrix tablets prepared with PEO or with HPMC of higher viscosity grade were exposed to UV irradiation, displacements of the drug release profiles were observed compared to the dissolution profile of the non-irradiated samples. In the case of PVA tablets, the exposure to UV light did not modify the dissolution profile of the matrices. The polymers that showed to be affected by UV irradiation, were then subjected to viscosity measurements. The rheological analysis indicates that viscosities of solutions prepared with irradiated PEO were much lower compared to the solution prepared with non-irradiated polymer. The same results, but less evident, were found for HPMC.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We hypothesized that the glucose metabolism of prostate cancer is modulated by androgen. We performed in vivo biodistribution and imaging studies of F-18 fluorodeoxyglucose (FDG) accumulation in ...androgen-sensitive (CWR-22) and androgen-independent (PC-3) human prostate cancer xenografts implanted in castrated and noncastrated male athymic mice. The growth pattern of the CWR-22 tumor was best approximated by an exponential function (tumor size in mm3 = 14.913 e(0.1086 x days), R2 = .96, n = 5). The growth pattern of the PC-3 tumor was best approximated by a quadratic function (tumor size in mm3 = 0.3511 x days2 + 49.418 x day - 753.33, R2 = .96, n = 3). The FDG accumulation in the CWR-22 tumor implanted in the castrated mice was significantly lower, by an average of 55%, in comparison to that implanted in the noncastrated host (1.27 vs. 2.83, respectively, p < .05). The 3-week maximal standardized uptake value (SUVmax) was 0.99 +/- 0.43 (mean +/- SD) for CWR-22 and 1.21 +/- 0.32 for PC-3, respectively. The 5-week SUVmax was 1.22 +/- 0.08 for CWR-22 and 1.35 +/- 0.17 for PC-3, respectively. The background muscle SUVmax was 0.53 +/- 0.11. Glucose metabolism was higher in the PC-3 tumor than in the CWR-22 tumor at both the 3-week (by 18%) and the 5-week (by 9.6%) micro-PET imaging sessions. Our results support the notions that FDG PET may be useful in the imaging evaluation of response to androgen ablation therapy and in the early prediction of hormone refractoriness in men with metastatic prostate cancer.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
495.
Site qualification in multicenter clinical trials McEwan, Alexander Sandy J B; Graham, Michael M; Conti, Peter S
The Journal of nuclear medicine (1978),
08/2009, Volume:
50, Issue:
8
Journal Article
Peer reviewed
Speaking at the workshop, Bernard Fine, MD, PhD, from Genentech, noted that the high rates of failure at every stage of the clinical trials process point to a critical need to improve evaluation ...procedures in earlystage drug evaluation, with the goal of reducing the number of pivotal phase 3 trials that fail.
Peptides, proteins, and nucleotides or DNA fragments are the new generation of drugs. They are becoming attractive owing to the fast development of biotechnology. The admnistration of such molecules, ...however, may be a problem as sensitivity to temperature, instability at some physiological pH values, short plasma half-life, and high molecular dimension, which hinders the diffusive transport, make, at the moment, parenteral route the only possible way of administration of such molecules. Controlled drug delivery that comprises the development of new administration routes could be the answer to the problems for administration of biotechnological molecules. The rational of drug delivery is to change the pharmacokinetic and pharmacodynamic of drugs by controlling their absorption and distribution. Rate and time of drug release at absorption site could be programmed using a so called delivery system. Different technologies, such as chemical (pro-drugs), biological, polymers, lipids (liposomes, LDL), have been proposed to obtain controlled drug release. Also the use of new administration routes is part of controlled drug delivery. In fact, it could increase the drug absorption and reduce the effects of the active ingredient in those districts not interested in the therapy. Drug delivery systems allowing for an effective release in vivo of new biotechnological molecules, such as recombinant antiidiotypic antibodies with antibiotic activity, devoted to the treatment of pulmonary (tuberculosis and pneumocystosis) and mucosal (candidiasis) diseases are discussed under that perspective.
Using spectroscopic parallax, the heliocentric and Galactocentric distances of nearly all of the 157 known Wolf-Rayet stars in the Galaxy were determined. Their distribution both within and ...perpendicular to the Galactic plane was investigated. The overall distribution within the plane reveals spiral features which are in accord with other determinations of Galactic structure. In addition, it was found that the Galactocentric location of Wolf-Rayet stars is dependent on Wolf-Rayet subtype, with late WC stars strongly confined to regions within the solar circle. However, there is only a marginal variation in the WC/WN number ratio with distance from the Galactic center. The distribution of Wolf-Rayet stars in the direction perpendicular to the plane reveals that these objects are closely confined to, but distributed asymmetrically about, the Galactic plane; the verical scale height of the distribution is about 45 pc. It is found that the sun is located about 15 pc above the plane defined by these extreme Population I objects. (Author)
The genetic basis of tolerance to abiotic stresses, i.e. the major constraints to maize production, is poorly understood. The utilization of molecular markers and genomics platforms offer ...unprecedented opportunities to identify, select and clone genes influencing tolerance to abiotic stresses, mainly a quantitative trait. The dissection of the genetic basis of quantitative traits into their single components, the so-called QTLs (Quantitative Trait Loci), provides a more direct access to valuable genetic diversity for important physiological processes that regulate the adaptive response of maize to abiotic stresses. This, in turn, enables us to utilize marker-assisted selection (MAS) for enhancing maize performance and/or producing isogenic lines at target QTLs. A large number of QTLs have been described to influence yield in maize exposed to abiotic stresses, particularly drought and chilling. The results of these studies are herein summarized. Despite the impressive list of QTLs so far described and the recent advances in high throughput profiling, the overall impact of MAS and other applications of genomics on the release of maize hybrids more tolerant to abiotic stresses has been negligible. Improving tolerance to abiotic stresses through marker technologies will require a deeper integration between MAS, conventional breeding methodologies and other interdisciplinary approaches. In the future, the cloning of major QTLs affecting tolerance to abiotic stresses coupled with other genomics platforms will offer additional opportunities for a more effective exploitation of the allelic richness present in maize germplasm collections
La base genetica della tolleranza agli stress abiotici, cioè ai limiti principali alla produzione del mais, è scarsamente conosciuta. L'utilizzazione di marcatori molecolari e di piattaforme di genomica offre opportunità senza precedenti per identificare, selezionare e clonare geni che influenzano la tolleranza agli stress abiotici, carattere prevalentemente quantitativo. La scissione della base genetica dei caratteri quantitativi nei loro singoli componenti, i cosiddetti QTL (Quantitative Trait Loci, loci di caratteri quantitativi), fornisce un accesso più diretto alla preziosa diversità genetica relativa a importanti processi fisiologici che regolano la risposta adattativa del mais agli stress abiotici. Questo, a sua volta, ci consente di utilizzare la selezione assistita da marcatori (MAS) per migliorare la performance del mais e/o produrre linee isogeniche a target QTL. E' stato descritto un largo numero di QTL che influenzano la resa nel mais esposto a stress abiotici, in particolare siccità e freddo. I risultati di questi studi sono sintetizzati in questo contributo. Nonostante la lista imponente di QTL finora descritti e i progressi recenti nel profiling ad alta produttività, l'impatto complessivo della MAS e delle altre applicazioni della genomica sulla produzione di ibridi di mais più tolleranti agli stress abiotici è stato finora trascurabile. Il miglioramento della tolleranza agli stress abiotici mediante le tecnologie dei marcatori richiederà un'integrazione più profonda fra MAS, metodi di miglioramento convenzionali e altri approcci disciplinari. In futuro, la clonazione dei QTL principali che influenzano la tolleranza agli stress abiotici abbinata ad altre piattaforme di genomica offrirà opportunità aggiuntive per uno sfruttamento più efficace della ricchezza allelica presente nelle collezioni di germoplasma di mais.
Summit participants in the Instrumentation and Animal Models breakout sessions focused on identifying common themes in development and practice, challenges that can be identified now or are likely to ...arise in the near future, and recommended strategies for preparing to meet these challenges in ways that continue to support the performance of high-quality scientific research in molecular imaging. At the same time, continued development depends on concerted action by researchers, academics, industry, and funding agencies to encourage agreement on and adoption of standards and harmonization in all aspects of animal imaging, including but not limited to animal handling, training, instrumentation, scanner software, image data, image analysis, methods of distribution, protocols, practice, and reporting.
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