Stacked in-plane histology for quantitative validation of non-invasive imaging biomarkers: Application to an infiltrative brain tumour model.

BACKGROUND: While it is generally agreed that histopathology is the gold standard for assessing non-invasive imaging biomarkers, most validation has been by qualitative visual comparison. To date, the difficulties involved in accurately co-registering histology sections with imaging slices have prevented a voxel-by-voxel assessment of imaging modalities. By contrast with previous studies, which focus on improving the registration algorithms, we have taken the approach of improving the quality of the histological processing and analysis. NEW METHOD: To account for imaging slice orientation and thickness, multiple histology sections were cut in the MR imaging plane and averaged to produce stacked in-plane histology (SIH) maps. When combined with intensity sensitive staining this approach gives histopathology maps, which can be used as the gold standard to validate imaging biomarkers. RESULTS: We applied this pipeline to a patient-derived mouse model of glioblastoma multiforme (GBM). Increasing the number of stacked histology sections significantly increased SIH measured tumour volume. The SIH technique proposed here resulted in reduced variability of volume measurements and this allowed significant improvements in the quantitative volumetric assessment of multiple MRI modalities. Further, high quality registration enabled a voxel-wise comparison between MRI and histopathology maps. Previous approaches to the validation of imaging biomarkers with histology, have been either qualitative or of limited accuracy. Here we propose a pipeline that allows for a more accurate validation via co-registration with SIH maps, potentially allowing validation in a voxel-wise mode. CONCLUSION: This work demonstrates that methodically produced SIH maps facilitate the quantitative histopathologic assessment of imaging biomarkers.

Quantitative histopathologic assessment of perfusion MRI as a marker of glioblastoma cell infiltration in and beyond the peritumoral edema region.

BACKGROUND: Conventional MRI fails to detect regions of glioblastoma cell infiltration beyond the contrast-enhanced T1 solid tumor region, with infiltrating tumor cells often migrating along host blood vessels. PURPOSE: To quantitatively and qualitatively analyze the correlation between perfusion MRI signal and tumor cell density in order to assess whether local perfusion perturbation could provide a useful biomarker of glioblastoma cell infiltration. STUDY TYPE: Animal model. SUBJECTS: Mice bearing orthotopic glioblastoma xenografts generated from a patient-derived glioblastoma cell line. FIELD STRENGTH/SEQUENCES: 7T perfusion images acquired using a high signal-to-noise ratio (SNR) multiple boli arterial spin labeling sequence were compared with conventional MRI (T1 /T2 weighted, contrast-enhanced T1 , diffusion-weighted, and apparent diffusion coefficient). ASSESSMENT: Immunohistochemistry sections were stained for human leukocyte antigen (probing human-derived tumor cells). To achieve quantitative MRI-tissue comparison, multiple histological slices cut in the MRI plane were stacked to produce tumor cell density maps acting as a "ground truth." STATISTICAL TESTS: Sensitivity, specificity, accuracy, and Dice similarity indices were calculated and a two-tailed, paired t-test used for statistical analysis. RESULTS: High comparison test results (Dice 0.62-0.72, Accuracy 0.86-0.88, Sensitivity 0.51-0.7, and Specificity 0.92-0.97) indicate a good segmentation for all imaging modalities and highlight the quality of the MRI tissue assessment protocol. Perfusion imaging exhibits higher sensitivity (0.7) than conventional MRI (0.51-0.61). MRI/histology voxel-to-voxel comparison revealed a negative correlation between tumor cell infiltration and perfusion at the tumor margins (P = 0.0004). DATA CONCLUSION: These results demonstrate the ability of perfusion imaging to probe regions of low tumor cell infiltration while confirming the sensitivity limitations of conventional imaging modalities. The quantitative relationship between tumor cell density and perfusion identified in and beyond the edematous T2 hyperintensity region surrounding macroscopic tumor could be used to detect marginal tumor cell infiltration with greater accuracy. LEVEL OF EVIDENCE: 1 Technical stage: 2 J. Magn. Reson. Imaging 2019;50:529-540.

Computed tomographic appearance of canine thyroid tumours.

OBJECTIVES: To describe the computed tomography features of canine thyroid tumours. METHODS Retrospective study of records of dogs with a thyroid tumour and neck computed tomography. Neck computed tomographies were evaluated for tumour characteristics. Thoracic radiographs and computed tomographies were evaluated for lung nodules. RESULTS: Of 19 identified cases, 17 were carcinomas and 2 were adenomas; 12 had mineralisation, 16 had heterogeneous attenuation and 16 were unilateral. Tumours were located from the temporomandibular joint to C5. Sixteen had well-defined margins postcontrast. Tumours were ovoid and mean volume was 57·4 cm(3) . By computed tomography, eight had definitive or possible invasion into surrounding structures; all eight were histopathologically invasive carcinomas. Five histopathologically non-invasive tumours and two adenomas had no computed tomography invasion into surrounding structures. Four had complete palpable mobility (two adenomas and two histopathologically invasive carcinomas); one had computed tomography evidence of possible invasion. The sensitivity of palpable mass mobility to determine histopathological invasion was 71% with 0% specificity. The sensitivity of computed tomography invasion to determine histopathological invasion was 70% with 100% specificity. CLINICAL SIGNIFICANCE: Computed tomography scans revealed several common features. Palpable mass mobility was not definitive for lack of histopathological invasion. Computed tomography invasion was specific but not very sensitive for histopathological invasion.

False-negative MRI biomarkers of tumour response to targeted cancer therapeutics.

BACKGROUND: Non-invasive quantitative imaging biomarkers are essential for the evaluation of novel targeted therapeutics. Before deployment in clinical trials, such imaging biomarkers require qualification, typically through pre-clinical identification of imaging-pathology correlates. METHODS: First, in investigating imaging biomarkers of invasion, the response of orthotopic murine PC3 prostate xenografts to the Src inhibitor saracatinib was assessed using susceptibility contrast MRI. Second, the longitudinal response of chemically induced rat mammary adenocarcinomas to the VEGFR2 inhibitor vandetanib was monitored by intrinsic susceptibility MRI, to identify the time window of transient vascular normalisation. RESULTS: No significant differences in fractional blood volume (%), vessel calibre (µm), native T(1) (ms) or apparent water diffusion coefficient were determined, despite reduced expression of activated Fak and paxillin in the saracatinib cohort. Treatment with vandetanib elicited a 60% antitumour response (P<0.01), 80% inhibition in vessel density (P<0.05) and reduction in hypoxia (P<0.05). There was, however, no significant change in tumour baseline R(2)* (s(-1)) or carbogen-induced ΔR(2)* with treatment. CONCLUSION: Reporting negative imaging biomarker responses is important, to avoid the risk of clinical trials using the same biomarkers being undertaken with a false expectation of success, and the abandonment of promising new therapeutics based on a false-negative imaging biomarker response being mistaken for a true-negative.

Isotopic evidence for breastfeeding and possible adult dietary differences from Late/Sub-Roman Britain.

Historical documents indicate that breastfeeding and weaning practices have fluctuated in England through history. In order to obtain evidence for general breastfeeding patterns in Late/Sub-Roman Britain, stable carbon and nitrogen isotope values were measured in juvenile and adult skeletons (n = 87) from the cemetery of Queenford Farm, Dorchester-on-Thames, Oxfordshire. As the site contained few individuals between 0-1.5 years of age, it was not possible to determine the initial timing for the introduction of weaning foods. Between ages 2-4 years, the mean +/- SD delta(13)C results (-20.2 +/- 0.3 per thousand) are significantly more negative (t = -4.03, P < 0.001) compared to adult females (-19.7 +/- 0.3 per thousand). This is interpreted as evidence of a different diet being fed to children during weaning. After age 2, the delta(15)N values gradually decline, indicating complete cessation of breastfeeding by 3-4 years. Among adults, stature (males = 1.68 +/- 0.06 m; females = 1.58 +/- 0.07 m) and sexual dimorphism (106) were low, suggesting that the population was possibly under environmental stress. The delta(13)C results for adults are similar, but females show a small but statistically significantly (t = -2.86, P < 0.01) lower mean delta(15)N value (9.9 +/- 0.9 per thousand) compared to males (10.6 +/- 0.5 per thousand). These lower female delta(15)N values possibly reflect the different physiology of the sexes (pregnancy and/or lactation) or the reduced consumption of animal/fish protein by women, and this may have been influenced by individual preference, family needs, or societal values of the era.

Expression of erbB-4/HER-4 growth factor receptor isoforms in ovarian cancer.

Immunohistochemical expression of erbB4 protein was identified in 93% (49 of 53) of ovarian cancers using the HFR-1 antibody (targeted to the cytoplasmic domain of the erbB4 receptor) and in 89% (47 of 53) of ovarian cancers using the H4.77.16 antibody (targeted to the extracellular domain). Tumors of serous histology were more likely to express a higher level of erbB4 than endometrioid tumors, and for stage III serous tumors, long-term survival was associated with moderate to high coexpression of erbB4 and erbB2. Within ovarian cancer cell lines, high erbB4 expression was associated with cisplatin resistance. Using reverse transcription-PCR, the presence of multiple isoforms of erbB4 mRNA was identified in both ovarian primary tumors and cell lines. Splice variants in the juxtamembrane (JM-a and JM-d) and cytoplasmic (CT-a and CT-b) regions were identified in mRNA of both cell lines and primary tumors. The use of an anti-erbB4 blocking antibody suggested that erbB4 was not the mediator of the growth stimulatory effects of neuregulin in ovarian cancer cells and indeed could potentially antagonize this effect.

ASP1 (BACE2) cleaves the amyloid precursor protein at the beta-secretase site.

Sequential proteolytic processing of the Amyloid Precursor Protein (APP) by beta- and gamma-secretases generates the 4-kDa amyloid (A beta) peptide, a key component of the amyloid plaques seen in Alzheimer's disease (AD). We and others have recently reported the identification and characterisation of an aspartic proteinase, Asp2 (BACE), as beta-secretase. Here we describe the characterization of a second highly related aspartic proteinase, Asp1 as a second beta-secretase candidate. Asp1 is expressed in brain as detected at the mRNA level and at the protein level. Transient expression of Asp1 in APP-expressing cells results in an increase in the level of beta-secretase-derived soluble APP and the corresponding carboxy-terminal fragment. Paradoxically there is a decrease in the level of soluble A beta secreted from the cells. Asp1 colocalizes with APP in the Golgi/endoplasmic reticulum compartments of cultured cells. Asp1, when expressed as an Fc fusion protein (Asp1-Fc), has the N-terminal sequence ALEP..., indicating that it has lost the prodomain. Asp1-Fc exhibits beta-secretase activity by cleaving both wild-type and Swedish variant (KM/NL) APP peptides at the beta-secretase site.

Long-term outcome of depressed children: a follow-up study.

Nineteen subjects diagnosed as clinically depressed in childhood were followed up seven to eight years after first presentation. The group was highly symptomatic when originally seen, a large proportion presenting with physical complaints. The outcome at follow-up was variable, but 42 per cent still had moderate or severe disability. This small study emphasises the need for further detailed investigation of the long-term outcome of children with a depressive disorder.

Determination of urinary carbamylaspartate and dihydro-orotate in normal subjects and in patients with hereditary orotic aciduria.

An isotope dilution assay for urinary dihydro-orotic acid and carbamylaspartic acid (CAA) has been developed which has been shown to yield accurate measurements for these pyrimidine precurosrs. Dihydro-orotic acid could not be detected in 24-hour urine specimens from 10 normal adults and 7 normal children, or in specimens from 2 children with hereditary orotic aciduria Type I. Small amounts (approximately 10 mumole per 24 hours) of carbamylaspartic acid are excreted in normal urine, and there was a modest elevation in CAA excretion in the 2 patients with hereditary orotic aciduria.

A muscarone-binding material in electroplax and its relation to the acetylcholine receptor. II. Dialysis assay.

An equilibrium dialysis technique, applied to lyophilized particulate fractions of Torpedo electroplax, gave data consistent with a single kind of macromolecular binding of muscarone, with binding constant, 7 x 10(-7)M and an amount of 1 nmole per gram original electroplax. The effects on muscarone binding of 38 drugs suggested that muscarone binding reflected acetylcholine receptor activity. Of 18 enzyme preparations, only trypsin, chymotrypsin, and phospholipase C reduced binding activity, suggesting that a phospholipoprotein was binding. Partial "solubilization" of the binding protein was achieved, but the "solubilized" activity did not migrate on electrophoresis. Additional evidence was provided that acetylcholinesterase was not responsible for this muscarone binding.

A muscarone-binding material in electroplax and its relation to the acetylcholine receptor. I. Centrifugal assay.

A muscarone-binding material has been found in Torpedo electroplax. The material behaves in several ways as one would expect of the binding component of the acetylcholine receptor, especially in its high affinity for muscarone (approximate K = 7 x 10(-6)M), acetylcholine (approximate K = 1.1 x 10(-6)M), curare, and nicotine, and its insensitivity to noncholinergic agents; the reversibility of its muscarone binding; and its suitably small amount (about 1.8 nmole/gm). The material appears not to be acetylcholinesterase.

Psilocybin: reaction with a fraction of rat brain.

Psilocybin, a hallucinogen, formed a blue color with a subfraction of rat-brain mitochondria believed to contain nerve-ending particles. Color formation increased with pH, did not require oxygen, and involved a component that could not be solubilized. The effect was not shown by chemically related neuroactive compounds, such as bufotenine and serotonin, and was antagonized by only tyramine or ethylenediaminetetraacetic acid.