Multi-site study of diffusion metric variability: effects of site, vendor, field strength, and echo time on regions-of-interest and histogram-bin analyses

It is now common for magnetic-resonance-imaging (MRI) based multi-site trials to include diffusion-weighted imaging (DWI) as part of the protocol. It is also common for these sites to possess MR scanners of different manufacturers, different software and hardware, and different software licenses. These differences mean that scanners may not be able to acquire data with the same number of gradient amplitude values and number of available gradient directions. Variability can also occur in achievable b-values and minimum echo times. The challenge of a multi-site study then, is to create a common protocol by understanding and then minimizing the effects of scanner variability and identifying reliable and accurate diffusion metrics. This study describes the effect of site, scanner vendor, field strength, and TE on two diffusion metrics: the first moment of the diffusion tensor field (mean diffusivity, MD), and the fractional anisotropy (FA) using two common analyses (region-of-interest and mean-bin value of whole brain histograms). The goal of the study was to identify sources of variability in diffusion-sensitized imaging and their influence on commonly reported metrics. The results demonstrate that the site, vendor, field strength, and echo time all contribute to variability in FA and MD, though to different extent. We conclude that characterization of the variability of DTI metrics due to site, vendor, field strength, and echo time is a worthwhile step in the construction of multi-center trials.

Multi-site Study of Diffusion Metric Variability: Characterizing the Effects of Site, Vendor, Field Strength, and Echo Time using the Histogram Distance

MRI-based multi-site trials now routinely include some form of diffusion-weighted imaging (DWI) in their protocol. These studies can include data originating from scanners built by different vendors, each with their own set of unique protocol restrictions, including restrictions on the number of available gradient directions, whether an externally-generated list of gradient directions can be used, and restrictions on the echo time (TE). One challenge of multi-site studies is to create a common imaging protocol that will result in a reliable and accurate set of diffusion metrics. The present study describes the effect of site, scanner vendor, field strength, and TE on two common metrics: the first moment of the diffusion tensor field (mean diffusivity, MD), and the fractional anisotropy (FA). We have shown in earlier work that ROI metrics and the mean of MD and FA histograms are not sufficiently sensitive for use in site characterization. Here we use the distance between whole brain histograms of FA and MD to investigate within- and between-site effects. We concluded that the variability of DTI metrics due to site, vendor, field strength, and echo time could influence the results in multi-center trials and that histogram distance is sensitive metrics for each of these variables.

Abstract P5-04-09: Copper chaperons as novel targets for therapy in triple-negative breast cancer (TNBC)

Background: Copper metabolism is frequently dysregulated in cancer and promotes tumorigenesis. Copper chelation was shown to delay tumor development, attenuate tumor growth, block angiogenesis and inhibit metastases in preclinical breast cancer models. Copper depletion with tetrathiomolybdate (TM) in on-going phase II study for breast cancer patients at high risk for relapse resulted in significant improvement in progression-free survival, especially in patients with TNBC. We hypothesized that targeting ATOX-1 and CCS, copper chaperons that are major regulators of copper trafficking, with novel selective inhibitor may disrupt cellular copper transport and suppress TNBC cell growth, block angiogenic activity, and enhance cytotoxicity of available chemotherapy.

Methods:We measured ATOX-1 and CCS protein expression using western blot in a panel of breast cancer cell lines including TNBC cell lines with basal-like (BL) and claudin-low (CL) subtypes. We compared potency and efficacy of ATOX-1/CCS inhibitor to induce cytotoxicity in MDA-MB231, MDA-MB436, MDA-MB468 and primary normal mammary HMECs. We evaluated ability of the inhibitor to disrupt tubulogenesis of endothelial cells. To determine if blocking copper transport can enhance sensitivity of TNBC to chemotherapy we used novel ATOX-1/CCS inhibitor in combination with Cisplatin to treat TNBC in a schedule-dependent manner.

Results: ATOX-1 protein expression was elevated in all tested TNBC cell lines compared to normal HMEC (1.7±0.2 and 2.1± 0.3 folds higher in BL and CL cells, respectively). Upregulated CCS protein expression was also observed in majority of tested cell lines compared to HMEC (2.8±0.6 and 1.2±0.1 times higher in BL and CL cells, respectively). Treatment of MDA-MB231, MDA-MB436, MDA-MB468 with the inhibitor resulted in reduced cell proliferation. IC50 doses for 72h treatment with single agent were: 0.23±0.02uM (MDA-MB468), 0.29±0.03uM (MDA-MB231) and 0.35±0.02uM (MDA-MB436). Additional cytotoxicity was observed in TNBC when ATOX-1/CCS inhibitor was applied in combination with Cisplatin. Interestingly, sequential treatment resulted in synergistic effect (CI< 1). Treatment with the inhibitor reduced growth of HMECs and HuVECs in vitro, and inhibited angiogenesis in tube formation assay with HuVECs.

Conclusions: Targeting copper trafficking by selective inhibition of chaperons ATOX-1 and CCS is promising and could potentially serve as a therapeutic approach to overcome resistance to chemotherapy in TNBC. In vivo studies investigating efficacy and biological activity of the novel compound in a xenograft model are ongoing and will help to elucidate molecular mechanisms of action, and further estimate potential clinical relevance of this approach.

Citation Format: Karginova O, Song A, Wang J, Luo C, Jiang H, He C, Olopade OI. Copper chaperons as novel targets for therapy in triple-negative breast cancer (TNBC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-04-09.

Carotid stenosis and cognitive impairment amongst older Chinese adults living in a rural area: a population-based study

BACKGROUND AND PURPOSE

The possible association between carotid stenosis and cognitive impairment in the Chinese population has been rarely investigated. The association between the severity of carotid stenosis and cognitive impairment amongst older Chinese people living in a rural area was assessed.

METHODS

This cross-sectional study included 1375 participants (age ≥60 years) from the Confucius Hometown Aging Project in Shandong. In 2010-2011, data were collected through interviews and clinical examinations. Carotid stenosis was assessed using ultrasonography. Cognitive impairment was defined according to the education-specific cutoff scores of the Mini-Mental State Examination. Data were analyzed using multinomial logistic models.

RESULTS

The overall prevalence was 7.0% for moderate carotid stenosis, 2.0% for severe stenosis and 6.0% for cognitive impairment. The multi-adjusted odds ratio of cognitive impairment was 1.43 (95% confidence interval 0.63-3.22) for moderate carotid stenosis and 3.75 (1.24-11.40) for severe carotid stenosis (P(trend) = 0.023). Similar results were obtained in people without a history of cerebrovascular disease.

CONCLUSIONS

Severe carotid stenosis, even asymptomatic, is associated with cognitive impairment independent of atherosclerotic risk factors and disorders amongst older Chinese people.

Evaluation of an antigen-capture EIA for the diagnosis of hepatitis E virus infection

An enzyme immunoassay (EIA) has been developed for hepatitis E virus (HEV) antigen (HEV-Ag) detection and marketed in China. This study aimed to evaluate the sensitivity of the assay and assess the value of HEV-Ag detection in the diagnosis of HEV infection in comparison with HEV RNA detection. Using serial dilutions of a genotype 4 HEV strain, significant correlation was found between the EIA (S/CO) and HEV RNA (IU/mL) concentration in the range 10(3.5) to 10(0.5) IU/mL HEV RNA, the Pearson correlation coefficient r approached 0.97. The EIA detection limit was 54.6 IU/mL, compared to 24 IU/mL for HEV RNA using real-time RT-PCR. In clinical samples from hepatitis E patients, the HEV-Ag and HEV RNA positivity rates were 55.6% (65/117) and 60.7% (71/117) in sera and 76.7% (56/73) and 84.9% (62/73) in stools, and the concordance of these two markers was 77.8% in sera and 80.8% in stools. In serum samples, the HEV-Ag positivity rate and the concordance between HEV-Ag and HEV RNA were inversely proportional to the presence of anti-HEV antibody. The presence of anti-HEV IgG could reduce the S/CO of the HEV-Ag EIA. These results reveal a significant correlation between the detection of HEV-Ag and HEV RNA. The sensitivity of the HEV-Ag EIA was lower than real-time RT-PCR but could be higher than conventional nested RT-PCR. Therefore, the detection of HEV-Ag in serum and faeces is valuable for the diagnosis and prognosis of HEV infection in developing regions where real-time RT-PCR is not available.

Effects of conservatively treated diseased cementum with or without EMD on in vitro cementoblast differentiation and in vivo cementum-like tissue formation of human periodontal ligament cells

OBJECTIVES

The present study aimed to evaluate the effects of conservatively treated diseased cementum on in vitro cementoblast differentiation and in vivo cementum-like tissue formation of human periodontal ligament cells (hPDLCs), and observe differential effects of enamel matrix derivative (EMD) on in vivo cementum formation by hPDLCs.

MATERIALS AND METHODS

Forty-eight cementum slices and 48 dentin slices were prepared from periodontitis compromised teeth, and hPDLCs were inoculated on to all root slices. Twenty-four co-cultured root slices of each group were used for mRNA expression of cementum attachment protein and CEMP1. With application of EMD, 24 co-cultured root slices (divided into groups C, D, C+E, D+E) were transplanted subcutaneously into nude mice. All root fragments were reviewed by histological analysis and immunohistochemical staining for bone sialoprotein.

RESULTS

mRNA expressions of cementum attachment protein and cementum protein - 1 from hPDLCs on cementum slices were statistically higher than those of dentin slices. Seven specimens of group C and 10 specimens of group C+E revealed a layer of cementum-like tissue (NFC) on surfaces of pre-existing cementum. NFC was thicker in group C+E than in group C. All NFCs were positively stained for bone sialoprotein, however, there was no NFC formation on dentin slices.

CONCLUSION

Conservatively treated diseased cementum promoted in vitro cementoblast differentiation and in vivo cementum-like tissue formation by hPDLCs, and the in vivo effect was enhanced by the presence of EMD.

Neutralizing antibodies against AAV2, AAV5 and AAV8 in healthy and HIV-1-infected subjects in China: implications for gene therapy using AAV vectors

Adeno-associated viruses (AAV) have attracted attention as potential vectors for gene therapy and vaccines against several diseases, including HIV-1 infection. However, the presence of neutralizing antibodies (NAbs) after natural AAV infections inhibits their transfection in re-exposed subjects. To identify candidate AAV vectors for therapeutic or prophylactic HIV vaccines, NAbs against AAV2, AAV5 and AAV8 were screened in the sera of healthy individuals in China and 10 developed countries and an HIV-1-infected Chinese population. Seroprevalence was higher for AAV2 (96.6%) and AAV8 (82.0%) than for AAV5 (40.2%) in normal Chinese subjects. Among individuals seropositive for AAV5, >80% had low NAb titers (<1:90). The prevalence and titers of NAbs against the three AAVs were significantly higher in China than in developed countries (P<0.01). The prevalence of NAbs against AAV5 did not differ significantly between healthy and HIV-1-infected Chinese subjects (P=0.39). Co-occurrence of NAbs against AAV2, AAV5, and AAV8 was observed in the healthy population, and 15, 41, and 41% of individuals were AAV2(+), AAV2(+)/AAV8(+), and AAV2(+)/AAV5(+)/AAV8(+), respectively. Therefore, AAV5 exposure is low in healthy and HIV-1-infected populations Chinese individuals, and vectors based on AAV5 may be appropriate for human gene therapy or vaccines.

Isolation and characterisation of Chrysanthemum crassum SOS1, encoding a putative plasma membrane Na(+) /H(+) antiporter

A full-length cDNA homologue of SOS1 (salt overly sensitive 1) was isolated from the salinity-tolerant species Chrysanthemum crassum and found to encode a Na(+) /H(+) antiporter, using degenerate PCR and RACE-PCR. The 3752-bp sequence comprised a 3438 bp open reading frame, encoding a 127-kDa protein with 12 transmembrane domains within its N terminal portion, and a hydrophilic cytoplasmic tail in its C-terminal portion. CcSOS1 appears to be a plasma membrane protein, and shares ∼62% identity at the peptide level with its Arabidopsis thaliana homologue. Expression of CcSOS1 in the roots of C. crassum was sensitive to salinity stress, while in the leaves CcSOS1 was down-regulated in the presence of abscisic acid. CcSOS1 transcript abundance was reduced in both roots and leaves of plants exposed to low temperature, while it was increased in leaves (but not in roots) after drought stress. CcSOS1 expression was not regulated in the presence of CaCl2 . A heterologous complementation assay in yeast suggested that CcSOS1 directs Na(+) efflux, mimicking the function of the endogenous NHA1 protein. Thus CcSOS1 appears to encode a salinity-inducible plasma membrane Na(+) /H(+) antiporter. This gene may be useful in transgenic approaches to improving the salinity tolerance of related ornamental species.