A better understanding of the growth kinetics of malignant tumors is of paramount importance for the development of more successful treatment strategies. Given the lack of clinical data at non-symptomatic stages, it has been conjectured, that in most solid malignant human tumors two or three decades elapse between the first carcinogenic stimulus and the clinical emergence of the neoplasm (Tubiana, 1986). Since a tumor is clinically detectable with conventional diagnostic tools at approximately 1 cm 3 in volume, representing a population of about 1 billion cells, some 30 cell doublings from the progenitory cancer cell must occur in order to reach this 'diagnostic' stage.Assuming typical volume doubling times of about 100 days, this scenario corresponds to a preclinical time of roughly 8 years . In the next 10 volume doublings up to about 10 3 cm 3 in size (which is reportedly lethal in primary breast cancer by Retsky, 1997), the clinical history of the tumor passes through a microscopic, avascular growth phase, followed by angiogenesis, necessary to sustain a macroscopic size (Folkman, 1971).Continuous tumor progression leads then eventually to local tissue invasion and metastasis, depending on the particular cancer type.A recent paper from West et al (2001) shows that, regardless of the different masses and development times, mammals, birds, fish and molluscs all share a common growth pattern.Provided that masses and growth times for the different organisms are properly rescaled, the same universal exponential curve fits their ontogenetic growth data. The authors explain this phenomenon with basic cellular mechanisms (West et al, 2002), assuming a common fractal pattern in the vascularization of the investigated taxa. In our case, m 0 and M are the initial and final masses of the tumor, and a is a parameter expected to be related to the tumor's characteristics (e.g., its ability to metastasize or invade, or its affinity for nutrients uptake). Since the definition of the parameters is non-trivial, a multistep fitting procedure is adopted for their determination. M are allowed to respectively decrease and increase, and y 0 and α reestimated until a best-fit (consistent with the available biological infomation) is obtained.For our analysis, we have used available data from the literature, spanning in vitro experiments (multicellular tumor spheroids (Chignola et al, 2000, Nirmala et al, 2001) as well as in vivo data (both, from animal models (Steel, 1977;Cividalli et al, 2002) and patients (Norton, 1988; Yorke et al, 1993). The results are presented in Figures 1, 2 and 3, respectively, and plotted against equation [2]. The data fit the universal growth curve very well. Table 1 presents an estimate of the relevant parameters and, further supporting our claim, shows very high R 2 correlation coefficients between actual and fitted data.In the following, we will briefly discuss possible implications of our conjecture that tumor growth also follows a universal law. proposed that, upon reaching a certain " critical" vo...

Objectives To investigate three-dimensional (3D) power

No abstract

Magnetic Nanoparticles (MNPs) are of great interest in biomedicine, due to their wide range of applications. During recent years, one of the most challenging goals is the development of new strategies to finely tune the unique properties of MNPs, in order to improve their effectiveness in the biomedical field. This review provides an up-to-date overview of the methods of synthesis and functionalization of MNPs focusing on Iron Oxide Nanoparticles (IONPs). Firstly, synthesis strategies for fabricating IONPs of different composition, sizes, shapes, and structures are outlined. We describe the close link between physicochemical properties and magnetic characterization, essential to developing innovative and powerful magnetic-driven nanocarriers. In conclusion, we provide a complete background of IONPs functionalization, safety, and applications for the treatment of Central Nervous System disorders.

Ultrasound-activated decafluoropentane/chitosan nanodroplets effectively release oxygen to the skin.

Perfluoropentane (PFP)-based oxygen-loaded nanobubbles (OLNBs) were previously proposed as adjuvant therapeutic tools for pathologies of different etiology sharing hypoxia as a common feature, including cancer, infection, and autoimmunity. Here we introduce a new platform of oxygen nanocarriers, based on 2H,3H-decafluoropentane (DFP) as core fluorocarbon. These new nanocarriers have been named oxygen-loaded nanodroplets (OLNDs) since DFP is liquid at body temperature, unlike gaseous PFP. Dextran-shelled OLNDs, available either in liquid or gel formulations, display spherical morphology, ~600 nm diameters, anionic charge, good oxygen carrying capacity, and no toxic effects on human keratinocytes after cell internalization. In vitro OLNDs result more effective in releasing oxygen to hypoxic environments than former OLNBs, as demonstrated by analysis through oxymetry. In vivo, OLNDs effectively enhance oxy-hemoglobin levels, as emerged from investigation by photoacoustic imaging. Interestingly, ultrasound (US) treatment further improves transdermal oxygen release from OLNDs. Taken together, these data suggest that US-activated, DFP-based OLNDs might be innovative, suitable and cost-effective devices to topically treat hypoxia-associated pathologies of the cutaneous tissues.

A classification in universality classes of broad categories of phenomenologies, belonging to physics and other disciplines, may be very useful for a cross fertilization among them and for the purpose of pattern recognition and interpretation of experimental data. We present here a simple scheme for the classification of nonlinear growth problems. The success of the scheme in predicting and characterizing the well known Gompertz, West, and logistic models, suggests to us the study of a hitherto unexplored class of nonlinear growth problems.

Compared with absent or reverse end-diastolic flow, the placentas from growth-restricted fetuses with positive end-diastolic flow showed a normal pattern of stem artery development, accompanied by increased capillary angiogenesis and terminal villous development. These features suggest an adaptive pathway for the placenta in the face of uteroplacental ischemia.