Purpose: To study, with computational models, the utility of power modulation to reduce tissue temperature heterogeneity for variable nanoparticle distributions in magnetic nanoparticle hyperthermia.
Methods: Tumour and surrounding tissue were modeled by elliptical two- and three-dimensional computational phantoms having six different nanoparticle distributions. Nanoparticles were modeled as point heat sources having amplitude-dependent loss power. The total number of nanoparticles was fixed, and their spatial distribution and heat output were varied. Heat transfer was computed by solving the Pennes’ bioheat equation using finite element methods (FEM) with temperature-dependent blood perfusion. Local temperature was regulated using a proportional-integral-derivative (PID) controller. Tissue temperature, thermal dose and tissue damage were calculated. The required minimum thermal dose delivered to the tumor was kept constant, and heating power was adjusted for comparison of both the heating methods.
Results: Modulated power heating produced lower and more homogeneous temperature distributions than did constant power heating for all studied nanoparticle distributions. For a concentrated nanoparticle distribution, located off-center within the tumor, the maximum temperatures inside the tumor were 16% lower for modulated power heating when compared to constant power heating. This resulted in less damage to surrounding normal tissue. Modulated power heating reached target thermal doses up to nine-fold more rapidly when compared to constant power heating.
Conclusions: Controlling the temperature at the tumor-healthy tissue boundary by modulating the heating power of magnetic nanoparticles demonstrably compensates for a variable nanoparticle distribution to deliver effective treatment. 相似文献
Metabolomics may reveal novel insights into the etiology of prostate cancer, for which few risk factors are established. We investigated the association between patterns in baseline plasma metabolite profile and subsequent prostate cancer risk, using data from 3,057 matched case–control sets from the European Prospective Investigation into Cancer and Nutrition (EPIC). We measured 119 metabolite concentrations in plasma samples, collected on average 9.4 years before diagnosis, by mass spectrometry (AbsoluteIDQ p180 Kit, Biocrates Life Sciences AG). Metabolite patterns were identified using treelet transform, a statistical method for identification of groups of correlated metabolites. Associations of metabolite patterns with prostate cancer risk (OR1SD) were estimated by conditional logistic regression. Supplementary analyses were conducted for metabolite patterns derived using principal component analysis and for individual metabolites. Men with metabolite profiles characterized by higher concentrations of either phosphatidylcholines or hydroxysphingomyelins (OR1SD = 0.77, 95% confidence interval 0.66–0.89), acylcarnitines C18:1 and C18:2, glutamate, ornithine and taurine (OR1SD = 0.72, 0.57–0.90), or lysophosphatidylcholines (OR1SD = 0.81, 0.69–0.95) had lower risk of advanced stage prostate cancer at diagnosis, with no evidence of heterogeneity by follow-up time. Similar associations were observed for the two former patterns with aggressive disease risk (the more aggressive subset of advanced stage), while the latter pattern was inversely related to risk of prostate cancer death (OR1SD = 0.77, 0.61–0.96). No associations were observed for prostate cancer overall or less aggressive tumor subtypes. In conclusion, metabolite patterns may be related to lower risk of more aggressive prostate tumors and prostate cancer death, and might be relevant to etiology of advanced stage prostate cancer. 相似文献
OBJECTIVE: The more atherogenic lipid profile seen in peritoneal dialysis (PD) patients cannot fully explain the increased incidence of atherosclerosis in this population. Oxidative modification of low-density lipoproteins (LDL) is considered to play a central role in the atherogenic process, whereas high-density lipoprotein (HDL) protects LDL from oxidation. On the other hand, it has been suggested that the LDL and HDL of PD patients are more resistant to oxidation than those of control subjects, while PD-HDL equally protects LDL from oxidation compared to control-HDL. Two HDL-associated enzymes have been shown to protect both LDL and HDL from oxidation: paraoxonase (PON1) and HDL-associated platelet-activating factor acetylhydrolase (HDL-PAF-AH). Furthermore, low PON1 activity and high total plasma PAF-AH concentration, which represents mainly the LDL-associated enzyme, have been shown to be independent risk factors for coronary artery events in the general population. However, there are limited data regarding possible alterations of these enzymes in PD patients. The aim of our study was to examine the possible alterations of PON1 and PAF-AH activities in patients undergoing PD. DESIGN: A cross-sectional study. SETTING: A university medical center. PARTICIPANTS: 56 PD patients of Caucasian origin and 86 matched controls were studied. MEASUREMENTS: In all subjects, serum PON1 activity toward paraoxon (paraoxonase) and phenylacetate (arylesterase), as well as total serum and HDL-PAF-AH activities were measured; PON1 genetic polymorphisms known to influence PON1 activity (Q192R and M55L) were determined. RESULTS: The PD patients exhibited significantly increased serum PON1 (paraoxonase) and PON1 (arylesterase) activities compared to controls, regardless of the PON1 polymorphisms or the levels of HDL cholesterol. Additionally, PD patients had significantly elevated activities of total serum PAF-AH and HDL-PAF-AH, independently of the levels of LDL or HDL cholesterol. The ratio of HDL-PAF-AH/ total PAF-AH, which has recently been suggested to be a potential marker of atherogenicity, was decreased in these patients compared to controls. Moreover, no difference in the prevalence of PON1 polymorphisms between PD patients and controls was found. CONCLUSION: The elevated activities of PON1 and HDL-PAF-AH could explain the increased resistance of PD-HDL to oxidation; the higher activity of total PAF-AH and the decreased HDL-PAF-AH/ total PAF-AH ratio could contribute to the increased incidence of atherosclerosis in these patients. 相似文献
Auditory event-related potentials (AERP) were elicited in 47 patients with relapsing-remitting (RR) multiple sclerosis (MS) and 24 age-matched controls. MS patients had significantly prolonged N2 and P3 latencies as well as low P3 amplitude compared with controls. Seven of them exceeded 3 standard deviations from the control mean values. The observed N2 and P3 alterations are associated with the patients' disability status as it is defined by the Kurtzke expanded disability status scale (EDSS), but are not related to the duration of the disease. A possible cognitive decline as reflected in the observed AERP components alterations in MS patients is subsequently discussed. 相似文献
In a phase II study, 21 patients with MDS (RAEB, RAEBt, CMML and RA and RAS with severe cytopenia) were randomized to be treated with 3 courses of GM-CSF (3 micrograms/kg/day s.c.) alone (11 patients) or in combination with AraC (20 mg/m2/d s.c.) (10 patients) for 14-d periods, interrupted by 14-d rest periods. Eight patients discontinued the treatment. In the GM-CSF group a marked increase in WBC and neutrophil counts during each course of treatment administration were seen in most patients. Platelet counts decreased in 14 of 24 courses of treatment in the GM-CSF plus AraC group but in none of the GM-CSF group. Although the changes in the circulating blood cells were transient and the counts tended to return to the pretreatment levels during the rest periods, some more durable effects were seen. In 3/6 patients of the GM-CSF group who completed the designed treatment, both WBC and neutrophils remained elevated above the pretreatment levels throughout the 3-month period of treatment, while in one of them thrombocytopenia improved considerably. In the GM-CSF plus AraC group, 4 out of the 7 patients who completed the treatment showed an improvement of neutropenia as well as anaemia. In these 4 patients the BM percentage of blasts was also decreased. In conclusion, the results of this study indicate that GM-CSF given intermittently improves leukopenia in some patients with MDS. In addition, the administration of GM-CSF seems to prevent granulocytopenia of concurrent AraC treatment and may be of benefit in the treatment of these diseases. 相似文献
The essential oils from 9 populations of MENTHA LONGIFOLIA (L.) L., ssp. LONGIFOLIA and ssp. PETIOLATA (Boiss.) Kokkini, growing wild in Greece, were investigated by means of GLC and GLC-MS. Piperitone oxide has been found as the main component in the essential oils of both subspecies while carvone only in some individuals of ssp. PETIOLATA (chemotype 2). 相似文献