Implementation of angular response function modeling in SPECT simulations with GATE

Among Monte Carlo simulation codes in medical imaging, the GATE simulation platform is widely used today given its flexibility and accuracy, despite long run times, which in SPECT simulations are mostly spent in tracking photons through the collimators. In this work, a tabulated model of the collimator/detector response was implemented within the GATE framework to significantly reduce the simulation times in SPECT. This implementation uses the angular response function (ARF) model. The performance of the implemented ARF approach has been compared to standard SPECT GATE simulations in terms of the ARF tables' accuracy, overall SPECT system performance and run times. Considering the simulation of the Siemens Symbia T SPECT system using high-energy collimators, differences of less than 1% were measured between the ARF-based and the standard GATE-based simulations, while considering the same noise level in the projections, acceleration factors of up to 180 were obtained when simulating a planar 364 keV source seen with the same SPECT system. The ARF-based and the standard GATE simulation results also agreed very well when considering a four-head SPECT simulation of a realistic Jaszczak phantom filled with iodine-131, with a resulting acceleration factor of 100. In conclusion, the implementation of an ARF-based model of collimator/detector response for SPECT simulations within GATE significantly reduces the simulation run times without compromising accuracy.

Control of postharvest decay on cherry tomatoes by marine yeast Rhodosporidium paludigenum and calcium chloride

AIMS

In this study, the potential of calcium chloride (CaCl(2)) application to improve the efficacy of the marine antagonist Rhodosporidium paludigenum in controlling postharvest diseases of cherry tomatoes was assessed.

METHODS AND RESULTS

CaCl(2) alone was found not to have any direct influence on the population growth of R. paludigenum in NYDB cultures or in cherry tomato wounds. However, the combined treatments with 1 x 10(8) cells ml(-1)R. paludigenum and CaCl(2) at the concentration from 0.5 to 2% showed high activities to reduce black rot caused by Alternaria alternata in cherry tomato wounds, significantly higher than those of R. paludigenum or CaCl(2) alone. Meanwhile, 0.5% CaCl(2) in combination with 1 x 10(8) cells ml(-1)R. paludigenum greatly inhibited the natural decay of cherry tomatoes in 21 days' storage at 25 degrees C.

CONCLUSIONS

The combination of R. paludigenum and CaCl(2) enhances the inhibition of black rot and natural decay of postharvest cherry tomatoes. The results from this study provide a new way to improve the efficiency of R. paludigenum in maintaining the quality of postharvest fruits and vegetables.

SIGNIFICANCE AND IMPACT OF THE STUDY

The marine yeast R. paludigenum combined with CaCl(2) has greatly potential use as an alternative to chemical fungicides in inhibiting postharvest decay on cherry tomatoes.

Clinical and economic impact of infusion reactions in patients with colorectal cancer treated with cetuximab

Background: Systemic agents in cancer treatment were often associated with possible infusion reactions (IRs). This study estimated the incidence of IRs requiring medical intervention and assessed the clinical and economic impacts of IRs in patients with colorectal cancer (CRC) treated with cetuximab.

Patients and methods: Details on patients with CRC receiving cetuximab in 2004–2006 were extracted from a large USA administrative claims database. IRs were identified based on the occurrence of outpatient treatment, emergency room (ER) visit, and/or hospitalization for hypersensitivity and allergic reactions. Multivariate regressions were used to examine potential risk factors and quantify the economic impact of IRs.

Results: A total of 1122 CRC patients receiving cetuximab were identified. The incidence of IRs requiring medical intervention was 8.4%. Sixty-eight percent of the patients had treatment disruptions and 34% discontinued cetuximab treatment. Mean adjusted costs were $13 863 for cetuximab administrations with an IR requiring ER visit or hospitalization and $6280 for those with an IR requiring outpatient treatment, compared with $4555 for those without an IR.

Conclusions: The incidence rate of cetuximab-related IRs requiring medical intervention in clinical practice was found to be higher than rates reported in the product label and clinical trials. The clinical and economic impacts of these IRs are substantial.

Managing water resources for sustainable development: the case of integrated river basin management in China

The emerging water crisis in China shows that the current institutional frameworks and policies with regard to water resources management are incapable of achieving an effective and satisfactory situation that includes Integrated River Basin Management (IRBM). This paper analyses this framework and related policies, examines their deficiencies in relation to all water stress problems and explores alternatives focusing on river basins. Water resources management reforms in modern China are reviewed and the main problems involved in transforming the current river management system into an IRBM-based system are analysed. The Huai River basin is used as an example of current river basin management, with quantitative data serving to show the scale and scope of the problems in the country as a whole. The institutional reforms required are discussed and a conceptual institutional framework is proposed to facilitate the implementation of IRBM in China. In particular, the roles, power and responsibilities of River Basin Commissions (RBCs) should be legally strengthened; the functions of supervising, decision-making and execution should be separated; and cross-sectoral legislation, institutional coordination and public participation at all levels should be promoted.

Evaluating adherence to medication in children and adolescents with HIV

OBJECTIVE

The study was aimed to evaluate the relationship between pharmacy supply, self-reported treatment adherence and HIV viral load in HIV-infected children.

METHODS

A retrospective (52 weeks) cohort study was conducted through the review of the existing databases. Pharmacy supply was classified as "home delivery" when the medications were delivered home and as "in pharmacy pick-up" when they were picked up at the pharmacy. Adherence was assessed through retrospective (3 days recall) self-report. Fisher's exact model, univariate and multivariate logistic regression analyses were used.

SETTINGS

The study collected data on 140 HIV-infected children (<18 years). Adherence, pharmacy supply information and HIV viral loads were obtained from clinical and research databases.

PATIENTS

The data from 127 HIV-infected children (60 boys and 67 girls; mean age 9.9 years) were collected.

MAIN OUTCOME MEASURES

Complete adherence (100%) was reported in only 24% of patients. With 40% of patients being rarely or never completely adherent, 64% of children achieved undetectable viral loads during the study period.

RESULTS

No association between pharmacy supply and self-reported adherence was found (p = 0.605). Self-reported adherence (p = 0.0328) and age (p = 0.025) were the significant predictors of reaching undetectable viral loads. Adolescents (>13 years) were significantly less likely to reach undetectable viral loads than children under 13 years (odds ratio 0.38; 95% CI 0.16 to 0.89).

CONCLUSION

In our study, pharmacy supply was not associated with self-reported adherence. Most importantly, adherence and age were significant predictors of reaching undetectable viral loads.

Factors affecting human supragingival biofilm composition. I. Plaque mass

BACKGROUND AND OBJECTIVE

Little is known about the factors that affect the microbial composition of supragingival biofilms. This study was designed to examine the relationship between total DNA probe counts of supragingival biofilm samples, clinical parameters and supragingival biofilm composition.

MATERIAL AND METHODS

Supragingival plaque samples were taken from 187 systemically healthy adult subjects (n = 4745 samples). All samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The relationship between total DNA probe counts and microbial composition was examined by subsetting the data into 10 groups based on 10 percentile increments of the total DNA probe counts. Differences among groups in terms of species counts and proportions were sought, as well as relationships of total plaque DNA probe count and clinical parameters.

RESULTS

There was a wide distribution in mean total DNA probe counts among the 187 subjects. With increasing total plaque levels there was a change in the proportions of individual species and microbial complexes. 'Small plaques' were characterized by high proportions of species in the yellow, orange, purple and 'other' complexes; plaques of moderate mass were characterized by high proportions of Actinomyces and purple complex species, while 'large plaques' exhibited increased proportions of green and orange complex species. Measures of gingival inflammation, pocket depth and recession were significantly positively associated with total DNA probe counts. Increased plaque numbers were related to increased pocket depth irrespective of presence or absence of gingival inflammation.

CONCLUSION

The proportions of individual species and microbial complexes in supragingival biofilms are influenced by the total numbers of organisms in the biofilm.

Comparison of intra-coronary cell transplantation after myocardial infarction: Autologous skeletal myoblasts versus bone marrow mesenchymal stem cells

Cell transplantation promises restoration of cardiac function after myocardial infarction (MI). Comparison of intracoronary cell transplantation with skeletal myoblasts (SMs) versus bone marrow mesenchymal stem cells (BM-MSCs) was carried out in rabbits with MI induced by ligation of the left anterior descending artery. The infarction-affected artery was injected with SMs, BM-MSCs or cell-free medium (control) 24 h post-infarction (n = 15 per group). At baseline, there were no differences in cardiac parameters between the groups. At 4 weeks post-transplantation, left ventricular ejection fraction significantly improved and left ventricular end-diastolic diameter was significantly decreased in the cell-treated groups compared with pre-transplantation and the control group. Engrafted cells were found in all of the cell-treated rabbits. The cell-treated animals had significantly higher numbers of neovessels compared with the control. No significant difference was seen between the SM and BM-MSC groups. In conclusion, intra-coronary transplantation of SMs and BM-MSCs induced neoangiogenesis with comparable enhancements of cardiac performance and reduced cardiac remodelling in a rabbit MI model.

Further evaluation of 11C-PD153035 as a molecular imaging probe for the assessment of the epidermal growth factor receptor status in non-small cell lung cancer patients

3590

Background: Epidermal growth factor receptor (EGFR) plays a key role in tumorgenosis and is therefore an important target for new therapeutic and prognostic strategies. Our pilot study has demonstrated that 11C-PD153035, a highly EGFR selective tracer for positron emission tomography (PET), accumulated in tumor mass of non-small cell lung cancer (NSCLC) and the tracer uptake correlated with EGFR expression. Here, we further evaluate correlation between the intensity of 11C-PD153035 uptake and EGFR protein expression level and gene mutation. Methods: Fourteen patients (45–71y, mean 59.2±9.2 y, Male: Female = 8:6, squamous carcinoma: adenocarcinoma = 9:5) with pathologically proved NSCLC were examined with PET using 11C-PD153035 one week before surgery. Radioactivity concentrations, derived from regions of interest (ROI), were analyzed mathematically to maximum standardized uptake value (SUVmax). The EGFR protein expression of surgical specimen was utilized by immunohistochemistry (IHC) with a three-tier system intensity scored and Western Blot assay. The EGFR genetic alterations in exon 19 and 21 were examined by direct sequencing of polymerase chain reaction (PCR) products. Results: 11C-PD153035 uptake was observed in 9 out of 14 NSCLC patients (mean SUV 3.94±1.06, range 0.8–5.9) and the biodistribution study further demonstrated accumulation of radioactivity in the tumor mass. The SUVmax of 11C-PD153035 molecular images did not correlate with tumor size and injection dose of the tracer. A closely correlation between SUVmax and EGFR protein expression as determined by IHC (r = 0.84, p = 0.005) was observed but not with the protein expression level of Western Blot analysis (r = 0.442, p = 0.114), as well as EGFR exon 19 (r = -0.078, p = 0.790) or exon 21 (r = 0.118, p = 0.689) gene mutation. With ROC analysis according to IHC intensity, the cut-off value of SUVmax was 2.45. Conclusions: PET with 11C-PD153035 might therefore be used to visualize EGFR pattern on tumor in NSCLC patients and for individualized planning of therapeutic strategies with EGFR targeted drugs, especially small-molecule TKIs (gefitinib and erlotinib) which targeting the intracellular EGFR tyrosine kinase domain as PD153035.

No significant financial relationships to disclose.

Brain metastases (BM) in breast (BC) and lung cancer (LC) patients

e12029

Background: Most BM arise from BC or LC. Few studies compare their attributes and distribution, though BC BM have been reported to more often involve the cerebellum. Methods: Brain scanning was for clinical evidence of BM. Contrast-enhanced computer-automated tomograms (CT) or magnetic resonance images (MRI) of brains of all BC and LC patients irradiated for BM between 1996 and 2008 were reviewed. BC epidermoid growth factor receptor2 (HER-2) expression was determined. Results: Data was from 63 BC and 59 LC patients; 58% of the BC and 55% of the LC patients had MRIs. MRIs showed more cerebellar BM (p = 0.047). Primary to BM diagnosis intervals were shorter for LC than for BC patients (p = 0.001), but LC BM were more edematous (0.019). BC patients had more cerebellar BM (p = 0.004) than LC patients, and more BM in the cerebellum only (p = 0.017). LC patient gender and small cell histology did not correlate with cerebellar BM. Both cerebrums and cerebellums of BC patients had more BM than those with LC (p = 0.020; 0.013). Cerebellar BMs were more frequent in brains with more cerebral BM (p = 0.0020). Amongst BC over-expressing HER-2 was a trend to more cerebellar BM (p = 0.072). Conclusions: LC BM, which elicit more edema, produce symptoms earlier than BC BM. There are larger numbers of BC BM, perhaps due to BC's longer disease course and responsiveness to therapy. BC causes more cerebellar mets than LC, often without cerebral BM. This may be due both to the larger number of BC BM, and a predilection for the cerebellum. Periodic brain MRI, more sensitive than CT to posterior fossa lesions, may be indicated in some BC patients, and early radiation may control multiple small BM.

No significant financial relationships to disclose.

A strategy for clinical guidance using PD biomarkers revealed from human primary (HuPrime) tumors transplanted in nude mice

e14612

Background: Most anticancer drug candidates, currently in clinical trials, have clear targets in molecular and cellular systems. However, such molecular targets are not always affected (or not correlated with efficacious endpoints) when the candidate is evaluated in a clinical setting. There is an urgent need to develop better biological tools and models to ease the transition between in vitro and in vivo, and between preclinical and clinical settings. Activation of tyrosine kinases in tumor cells has been recognized as key driving force in malignancy; therefore inhibitors of tyrosine kinases (TKI) have often shown efficacy in preclinical in vivo models and beneficial responses in clinical trials. An increasing number of TKI has been approved as anticancer drugs in selected cancer types. Methods: We have developed a unique platform combining our novel HuPrime™ xenograft models with our PD biomarker technologies. This platform is used to better understand the efficacy of novel drug candidates and generate information critical to maximize the chance of a successful clinical development. To illustrate the usefulness of our platform, we have applied it to understand the pharmacodynamic changes (at the molecular level) which are associated with the activity of sunitinib and sorafenib in our sensitive esophageal HuPrime models. Tumor tissues from sensitive esophageal HuPrime models treated with single dose of the respective drugs (and a vehicle control) have been collected at time-points 4, 8, 16, and 24 hour. Results: We have successfully applied immunohistochemistry (IHC) assays on many molecules covering most pathways including proliferation, apoptotic, necrotic, and cell cycle regulation, G2M phase arrest, DNA damage response, etc. Additional markers including angiogenesis can also be included for certain therapeutic compounds. These tissues have been analyzed with our platform and we have uncovered key molecular events which correlate with the efficacy and potency of the drugs. Conclusions: The PD biomarkers validated in this approach have potential for clinical application and patient stratification.

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Thyroid hormone beta receptor activation has additive cholesterol lowering activity in combination with atorvastatin in rabbits, dogs and monkeys

BACKGROUND AND PURPOSE

Thyroid hormone receptor (TR) agonists are in clinical trials for the treatment of hypercholesterolaemia. As statins are the standard of clinical care, any new therapies must have adjunctive activity, when given in combination with statins. As already known for the statins, the cholesterol lowering effect of TR activation involves increased expression of the low-density lipoprotein receptor. Using animal models, we tested whether TR activation would have additive cholesterol lowering activity in the presence of effective doses of a statin.

EXPERIMENTAL APPROACH

We evaluated the activity of a liver-targeted prodrug, MB07811, of a novel TH receptor beta agonist, MB07344, as monotherapy and in combination with atorvastatin in rabbits, dogs and monkeys.

KEY RESULTS

In rabbits, MB07344 (i.v.) decreased total plasma cholesterol (TPC) comparable to that achieved with a maximally effective dose of atorvastatin (p.o.). The addition of MB07344 to atorvastatin resulted in a further decrease in TPC. Similarly, the addition of MB07811 (p.o.) to atorvastatin treatment decreased TPC beyond the level achieved with either agent as monotherapy. In dogs and monkeys, atorvastatin and MB07811 were administered as monotherapy or in combination. Consistent with the rabbit studies, the combination treatment caused a greater decrease in TPC than either MB07811 or atorvastatin administered as monotherapy.

CONCLUSIONS AND IMPLICATIONS

We conclude that the effects of MB07811 and atorvastatin in lowering cholesterol are additive in animals. These results would encourage and support the demonstration of similarly improved efficacy of combination versus monotherapy with such agents in the clinic.

The inhibitory effect of human embryonic germ cells on ovarian cancer

Cancer cells share numerous characteristics with pluripotent stem cells which develop normally, contributing to the tumor cell plasticity. So we investigated the effect of human embryonic germ cells (hEGCs) on SKOV3 cells. We examined the efficacy of hEGCs through coculturing SKOV3 with hEGCs, detecting tunel apoptosis and caspase-9 activity by immunocytochemistry, and measuring the expression of AKT by real-time PCR and western blot. Further a xenograft model in SCID mouse to examine the effect of hEGCs on SKOV3 in vivo was used. Our results showed that there was a 1.5-fold growth reduction for SKOV3 in the coculture group. HEGCs induced apoptosis via caspase-9 activation and AKT downregulation in SKOV3. This tumor cell inhibition was demonstrated also in the used animal tumor model. Taken together, our observations demonstrated that the hEGCs could inhibit the growth of SKOV3 by inducing apoptosis by inhibiting AKT pathway. Key words: embryonic germ cells; ovarian cancer; apoptosis.

Interactions between stem cells and their niche in the Drosophila ovary

The Drosophila ovary contains at least three types of active stem cells, namely, germ-line stem cells (GSCs), escort stem cells (ESCs), and follicular stem cells (FSCs), which work together to efficiently assemble egg chambers. Among the three stem cell types, the GSC is among the first shown to be controlled by the niche due to its easy identification and welldefined surrounding cells. We have shown that the niche controls GSC self-renewal, anchorage, aging, and competition, and the GSC also signals back to the niche for its maintenance. The FSC is an attractive model for studying epithelial stem cell regulation and signal integration because we have shown that it resembles mammalian epithelial stem cells and requires multiple signaling pathways for its self-renewal. In this chapter, we have highlighted the findings of our studies on interactions between Drosophila ovarian stem cells and their niches during normal development and aging and on stem cell competition for niche occupancy. We further discuss their implications in general stem cell biology and future directions in this exciting area.

Factors affecting human supragingival biofilm composition. II. Tooth position

BACKGROUND AND OBJECTIVE

Little is known regarding the factors that affect the microbial composition of supragingival biofilms. This study was designed to test the hypothesis that tooth location affects the microbial composition of supragingival plaque beyond the effect due to plaque mass as reflected by total DNA probe count.

MATERIAL AND METHODS

Supragingival plaque samples were taken from the mesiobuccal aspect of each tooth in 187 subjects (n = 4745 samples). All samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. Significance of differences in mean species counts and proportions were determined among tooth surfaces and six tooth type categories: molars, bicuspids, incisors/canines in the mandible and maxilla separately using the Kruskal-Wallis test. Stepwise multiple linear regression was employed to examine the relationship between species proportions and total DNA probe count, tooth location, periodontal and smoking status, age and sex.

RESULTS

All species differed significantly among tooth types and among the six tooth categories. Higher plaque levels were seen on molars and lower incisors. Some differences observed between tooth types could be partly explained by the level of plaque. Teeth with high plaque mass exhibited high levels of Capnocytophaga gingivalis, Actinomyces naeslundii genospecies 2, Campylobacter rectus and Campylobacter showae. However, certain species, such as Veillonella parvula and Streptococcus sanguinis, differed significantly at different tooth locations despite similarities in plaque mass. Twenty of the test species exhibited a significant association with tooth location after adjusting for total DNA probe count and subject level factors.

CONCLUSION

While plaque mass was associated with differences in proportions of many species in supragingival biofilms, tooth location also was strongly associated with species proportions in both univariate and multivariate analyses.