Relationships of body habitus and SUV indices with signal-to-noise ratio of hepatic (18)F-FDG PET

OBJECTIVE

Tissue accumulation of (18)F-FDG is quantified as standardised uptake value (SUV), which may be expressed as the voxel maximum (SUVmax) or mean (SUVmean). SUVmax/SUVmean may be a marker of hepatic steatosis, while the coefficient of variation (CV) of SUV may be a marker of hepatic fat distribution heterogeneity (HFDH). Alternatively, they may reflect low signal-to-noise ratio ('noise') in obese persons in whom hepatic steatosis is common. The study aim was to compare the impact of body size on noise versus SUV and CT density (CTD).

METHODS

Dynamic PET was performed (30×1min frames) following FDG injection in 60 patients undergoing routine PET/CT. Hepatic FDG clearance was measured using Patlak-Rutland graphical analysis with abdominal aorta as input. Noise was quantified as the standard deviation (SD) of the plot residuals (ignoring the first 2 frames), normalised to the intercept (NRMSD). SUVmax, SUVmean and CTD were measured from 60min whole body PET/CT. CV of SUV and SD of CTD were quantified in 28/60 patients using texture analysis.

RESULTS

NRMSD correlated with weight (r=0.49; p<0.0001) and BMI (r=0.48; p=0.0001). SUVmax, SUVmean, SUVmax/SUVmean, CV of SUV, CTD, and SD of CTD all correlated strongly with weight and BMI (p<0.0001). However, they correlated weakly with NRMSD, the strongest being SUVmax (r=0.34; p=0.008) and SD of CTD (r=0.42; n=28; p=0.026).

CONCLUSIONS

Noise is increased in overweight/obese persons but has little effect on SUV indices, CTD and their variabilities. SUVmax/SUVmean and CV of SUV are therefore, to some extent, markers of hepatic steatosis and HFDH, respectively.

Investigation on the structural, dielectric and impedance analysis of manganese substituted cobalt ferrite i.e., Co1−xMnxFe2O4 (0.0 ≤ x ≤ 0.4)

The microstructure and cation distribution of Co_1−xMnxFe₂O₄ were investigated and correlated with their electrical properties. Here, Mn substitution enhances the resistive properties which make them favorable for high-frequency applications.

Texture analysis of (125)I-A5B7 anti-CEA antibody SPECT differentiates metastatic colorectal cancer model phenotypes and anti-vascular therapy response

BACKGROUND

We aimed to test the ability of texture analysis to differentiate the spatial heterogeneity of (125)I-A5B7 anti-carcinoembryonic antigen antibody distribution by nano-single photon emission computed tomography (SPECT) in well-differentiated (SW1222) and poorly differentiated (LS174T) hepatic metastatic colorectal cancer models before and after combretastatin A1 di-phosphate anti-vascular therapy.

METHODS

Nano-SPECT imaging was performed following tail vein injection of 20 MBq (125)I-A5B7 in control CD1 nude mice (LS174T, n=3 and SW1222, n=4), and CA1P-treated mice (LS174T, n=3; SW1222, n=4) with liver metastases. Grey-level co-occurrence matrix textural features (uniformity, homogeneity, entropy and contrast) were calculated in up to three liver metastases in 14 mice from control and treatment groups.

RESULTS

Before treatment, the LS174T metastases (n=7) were more heterogeneous than SW1222 metastases (n=12) (uniformity, P=0.028; homogeneity, P=0.01; contrast, P=0.045). Following CA1P, LS174T metastases (n=8) showed less heterogeneity than untreated LS174T controls (uniformity, P=0.021; entropy, P=0.006). Combretastatin A1 di-phosphate-treated SW1222 metastases (n=11) showed no difference in texture features compared with controls (all P>0.05).

CONCLUSIONS

Supporting the potential for novel imaging biomarkers, texture analysis of (125)I-A5B7 SPECT shows differences in spatial heterogeneity of antibody distribution between well-differentiated (SW1222) and poorly differentiated (LS174T) liver metastases before treatment. Following anti-vascular treatment, LS174T metastases, but not SW1222 metastases, were less heterogeneous.

Routine histological analysis of a macroscopically normal gallbladder--a review of the literature

BACKGROUND

70,000 cholecystectomies were performed in the United Kingdom in 2011-2012. Currently it is standard practice to submit all gallbladder specimens for routine histology to exclude malignancy. The aim of this systematic review was to establish whether a normal macroscopic appearance to the gallbladder at the time of cholecystectomy is sufficient to rule out malignancy and therefore negate the need for routine histology.

METHODS

Relevant articles that were published between 1966 and January 2013 were identified through electronic databases.

RESULTS

21 studies reported on 34,499 histologically analysed specimens. 172/187 (92%) of gallbladder cancers demonstrated intra-operative macroscopic abnormality. Studies that opened the specimens intra-operatively identified all cancers, whereas gross macroscopic visualization resulted in 15 potentially missed cancers (p = 0.10). In patients of European ethnicity, gallbladder cancer in a macroscopically normal looking gallbladder was identified in only one study; however all of these patients were above the age of 60. The incidence of gallbladder cancer was significantly raised in ethnic groups from high risk areas (p = 0.0001).

CONCLUSIONS

A macroscopically normal gallbladder in patients of European ethnicity under the age of 60 may not require formal histopathology. The best method for intra-operative examination may involve opening the specimen to allow inspection of the mucosa and wall, however this needs further investigation. In the context of the volume of gallbladder surgery being performed there is the potential for significant cost and time savings.

An unusual dimeric small heat shock protein provides insight into the mechanism of this class of chaperones

Small heat shock proteins (sHSPs) are virtually ubiquitous stress proteins that are also found in many normal tissues and accumulate in diseases of protein folding. They generally act as ATP-independent chaperones to bind and stabilize denaturing proteins that can be later reactivated by ATP-dependent Hsp70/DnaK, but the mechanism of substrate capture by sHSPs remains poorly understood. A majority of sHSPs form large oligomers, a property that has been linked to their effective chaperone action. We describe AtHsp18.5 from Arabidopsis thaliana, demonstrating that it is dimeric and exhibits robust chaperone activity, which adds support to the model that suboligomeric sHSP forms are a substrate binding species. Notably, like oligomeric sHSPs, when bound to substrate, AtHsp18.5 assembles into large complexes, indicating that reformation of sHSP oligomeric contacts is not required for assembly of sHSP-substrate complexes. Monomers of AtHsp18.5 freely exchange between dimers but fail to coassemble in vitro with dodecameric plant cytosolic sHSPs, suggesting that AtHsp18.5 does not interact by coassembly with these other sHSPs in vivo. Data from controlled proteolysis and hydrogen-deuterium exchange coupled with mass spectrometry show that the N- and C-termini of AtHsp18.5 are highly accessible and lack stable secondary structure, most likely a requirement for substrate interaction. Chaperone activity of a series of AtHsp18.5 truncation mutants confirms that the N-terminal arm is required for substrate protection and that different substrates interact differently with the N-terminal arm. In total, these data imply that the core α-crystallin domain of the sHSPs is a platform for flexible arms that capture substrates to maintain their solubility.

Differences in regional bone metabolism at the spine and hip: a quantitative study using (18)F-fluoride positron emission tomography

SUMMARY

This study showed that regional bone blood flow and (18)F-fluoride bone plasma clearance measured by positron emission tomography are three times lower at the hip than the lumbar spine.

INTRODUCTION

Measurements of effective bone plasma flow (K (1)), bone plasma clearance (K ( i )) and standardised uptake values (SUV) using (18)F-fluoride positron emission tomography ((18)F-PET) provide a useful means of studying regional bone metabolism at different sites in the skeleton. This study compares the regional (18)F-fluoride kinetics and SUV at the hip and lumbar spine (LS).

METHODS

Twelve healthy postmenopausal women with no history of metabolic bone disease apart from two with untreated osteoporosis were recruited. Each subject underwent 60-min dynamic (18)F-PET scans at the LS and proximal femur two weeks apart. K (1), K ( i ) and SUV were measured at the LS (mean of L(1)-L(4)), femoral neck (FN), total hip (TH) and femoral shaft (FS). Differences between sites were assessed using the nonparametric Kruskal-Wallis test with a Bonferroni correction for multiple comparisons.

RESULTS

Values of K (1), K ( i ) and SUV at the FN, TH and FS were three times lower than at the LS (p = 0.003). Amongst the proximal femur sites, K ( i ) and SUV were lower at the FS compared with the FN and TH, and SUV was lower at the TH compared with the FN (all p < 0.05). The volume of distribution was lower at the TH and FS compared with the LS (p < 0.05).

CONCLUSION

The lower values of K (1), K ( i ) and SUV at the hip suggest that lower bone blood flow in the proximal femur is an important factor explaining the principal reason for the differences in bone fluoride kinetics between the LS and hip sites.

Precision of ¹⁸F-fluoride PET skeletal kinetic studies in the assessment of bone metabolism

We assessed the precision of lumbar spine (18)F-PET measurements based on 58 scans performed on 20 postmenopausal women. The percentage coefficient of variation (%CV) (95% confidence interval) was 9.2% (7.5-11.8) for standardised uptake values, 11.7% (9.5-14.9) for plasma clearance measurements using the Patlak method and 14.5% (11.7-18.5) for plasma clearance measurements using the Hawkins three-compartment model.

INTRODUCTION

(18)F-Fluoride positron emission tomography ((18)F-PET) is a non-invasive technique that allows the assessment of regional bone turnover in patients with metabolic bone disease. Knowledge of the precision errors of (18)F-PET measurements is important for planning the number of subjects required for research studies.

METHODS

Twenty osteoporotic postmenopausal women had (18)F-PET scans of the lumbar spine at 0, 6 and 12 months after stopping long-term bisphosphonate treatment. No significant changes in the PET measurements were seen over the 12-month period, and the data were deemed suitable for a precision study. Precision errors were evaluated for standardised uptake values (SUVs) and for the fluoride plasma clearance to bone mineral (K (i)) determined using the Patlak and Hawkins methods. Precision errors were expressed as the %CV and were calculated for the mean L1-L4 region and for individual vertebrae.

RESULTS

%CV (95% confidence interval) for the L1-L4 region was 9.2% (7.5-11.8) for SUV, 11.7% (9.5-14.9) for K (i) measured using the Patlak method and 14.5% (11.7-18.5) for K (i) measured using the Hawkins method. There was no significant difference between precision errors obtained for the L1-L4 region and those obtained for a single vertebra.

CONCLUSIONS

SUV measurements showed the smallest precision error followed by the Patlak method, while the Hawkins method gave the largest error. Measuring a smaller region of interest did not increase the precision error, suggesting that the factor determining the errors may be scanner calibration.

Regional bone metabolism at the lumbar spine and hip following discontinuation of alendronate and risedronate treatment in postmenopausal women

The aim of this study was to examine the effects of bisphosphonate discontinuation on bone metabolism at the spine and hip measured using (18) F-fluoride PET. Bone metabolism at the spine remained stable following discontinuation of alendronate and risedronate at 1 year but increased in the hip in the alendronate group only.

INTRODUCTION

Bisphosphonates such as alendronate (ALN) or risedronate (RIS) have persistent effects on spine BMD following discontinuation.

METHODS

Positron emission tomography (PET) was used to examine regional bone metabolism in 20 postmenopausal women treated with ALN (n = 11) or RIS (n = 9) for a minimum of 3 years at screening (range 3-9 years, mean 5 years for both groups). Subjects underwent a dynamic scan of the lumbar spine and a static scan of both hips at baseline and 6 and 12 months following treatment discontinuation. (18) F-fluoride plasma clearance (K(i)) at the spine was calculated using a three-compartment model. Standardised uptake values (SUV) were calculated for the spine, total hip, femoral neck and femoral shaft. Measurements of BMD and biochemical markers of bone turnover were also performed.

RESULTS

With the exception of a significant decrease in spine BMD in the ALN group, BMD remained stable. Bone turnover markers increased significantly from baseline by 12 months for both study groups. Measurements of K(i) and SUV at the spine and femoral neck did not change significantly in either group. SUV at the femoral shaft and total hip increased significantly but in the ALN group only, increasing by 33.8% (p = 0.028) and 24.0% (p = 0.013), respectively.

CONCLUSIONS

Bone metabolism at the spine remained suppressed following treatment discontinuation. A significant increase in SUV at the femoral shaft and total hip after 12 months was observed but for the ALN group only. This study was small, and further clinical studies are required to fully evaluate the persistence of BP treatment.

Use of ultrasonic pachymetry for measurement of changes in corneal thickness in mouse corneal transplant rejection

BACKGROUND/AIMS

Diagnosis of rejection in the mouse model of corneal transplantation is based on subjective judgement of loss of graft transparency. The aims of this study were to (1) evaluate a pachymetry technique to measure changes in mouse corneal thickness and (2) correlate increases in transplant thickness with clinical and histological features of rejection.

METHODS

Orthotopic corneal allografts (C57BL/6 strain donor) and syngeneic grafts were performed in A/J mice. Graft transparency was graded and corneal thickness measured by pachymetry on alternate days. Transverse sections of donor cornea excised from eyes representative of clinical opacity grades 1-4 were prepared, photographed, graft section thickness measured and stromal graft-infiltrating cells counted. Intraobserver and interobserver variations in pachymetry were statistically tested.

RESULTS

Graft thickness, as measured by pachymetry, increased with each clinical opacity grade. Thickness for opacity grades 0, 1 and 2 was less than 300 microm in all recipients. Graft thickness for grades 3 and 4 was greater than 300 microm in all cases. For measurements up to 400 mum, there was a good correlation between thickness as measured by in vivo pachymetry and in histopathological sections. The mean interobserver bias was -11.35 microm, while the mean intraobserver bias was +3.96 microm. Stromal cellularity increased with increasing corneal thickness up to approximately 300 microm.

CONCLUSION

In vivo graft pachymetry provides a new and reliable way to objectively diagnose rejection in the mouse model of corneal transplantation.

The plant sHSP superfamily: five new members in Arabidopsis thaliana with unexpected properties

The small heat shock proteins (sHsps), which are ubiquitous stress proteins proposed to act as chaperones, are encoded by an unusually complex gene family in plants. Plant sHsps are classified into different subfamilies according to amino acid sequence similarity and localization to distinct subcellular compartments. In the whole Arabidopsis thaliana genome, 19 genes were annotated to encode sHsps, of which 14 belong to previously defined plant sHsp families. In this paper, we report studies of the five additional sHsp genes in A. thaliana, which can now be shown to represent evolutionarily distinct sHsp subfamilies also found in other plant species. While two of these five sHsps show expression patterns typical of the other 14 genes, three have unusual tissue specific and developmental profiles and do not respond to heat induction. Analysis of intracellular targeting indicates that one sHsp represents a new class of mitochondrion-targeted sHsps, while the others are cytosolic/nuclear, some of which may cooperate with other sHsps in formation of heat stress granules. Three of the five new proteins were purified and tested for chaperone activity in vitro. Altogether, these studies complete our basic understanding of the sHsp chaperone family in plants.

DNA vaccination with VP2 gene of very virulent infectious bursal disease virus (vvIBDV) delivered by transgenic E. coli DH5alpha given orally confers protective immune responses in chickens

The efficacy of different doses of oral DNA vaccines carrying VP2 gene of vvIBDV delivered by E. coli DH5alpha was studied and compared with purified VP2 recombinant expression plasmid DNA vaccine injected intradermally and whole virus vaccine either from homologous virus or from commercial source. The recombinant plasmid pRc-VP2 was transformed in a non-pathogenic strain of E. coli, the DH5alpha and designated as EC/pRC-VP2. Oral immunization of maternal antibody free broiler chickens at 7 and 14-day-old with different dosages of EC/pRc-VP2 elicited specific humoral immune response as measured by ELISA. Protection in different groups was calculated through clinical signs, gross and histopathological lesions, bursa of Fabricius to body weight ratio, humoral and cellular immune responses and mortality in the chickens. Vaccination with EC/pRc-VP2 at the dose rate of 10(9)CFU per chicken conferred 95.4% protection of the chickens against the challenge with homologous virulent field strain of vvIBDV. Protection afforded by attenuated vero cell adapted UAF-06 strain of vvIBDV was comparable (94%) to that by EC/pRc-VP2 and pRc-VP2 vaccines, which was significantly higher (P<0.05) than the protection provided by a commercial attenuated IBDV stain D-78 vaccine (D-78 vaccine was used as positive control due to its frequent use in the field for vaccination of poultry chickens) and other control groups in the study. The results revealed that DNA vaccines against IBDV may be successfully done by adopting bacterial-vectored oral delivery system and vaccination with homologous vvIBDV (UAF-06) conferred significantly higher protection as compared with imported non-homologous commercial IBDV vaccine.

Protection capability of recombinant plasmid DNA vaccine containing VP2 gene of very virulent infectious bursal disease virus in chickens adjuvanted with CpG oligodeoxynucleotide

In the present study the efficacy of recombinant plasmids DNA vaccine encoding VP2 gene of very virulent strain of infectious bursal disease virus (vvIBDV) isolated from Pakistan was investigated with or without coadministration of cytocine-phosphate-guanine oligodeoxynucleotide (CpG ODN) to protect the chickens against the disease. VP2 gene of vvIBDV was successfully amplified by reverse transcription-polymerase chain reaction (RT-PCR) and was cloned into eukaryotic expression plasmid vector, which consisted of human cytomegalovirus (HCMV) immediate early enhancer and promoter, adenopartite leader sequences and SV-40 polyadenylation signal, and this was designated as pRc-VP2. Seven-day-old maternal antibodies free chickens were intramuscularly injected with 500 microg of pRc-VP2 with or without CpG ODN twice at 1-week interval. At the age of 21 days the broiler chickens were challenged with 10(5) EID(50) of homologous strain of IBDV and observed for 14 days post-challenge. Immunization with pRc-VP2 plus CpG ODN conferred protection in 93% of the chickens as evidenced by the absence of clinical signs, atrophy of bursa of Fabricius (BF) and mortality followed by the group vaccinated with attenuated IBD vaccine and boosted with killed oil based IBDV vaccine, which conferred 90% protection. The protection of chickens injected with pRc-VP2 alone was 67% where as only 20% of the chickens in the negative control group were protected. However, enzyme-linked immunosorbent assay (ELISA) antibody titre in the group vaccinated with pRc-VP2 plus CpG ODN were significantly higher (P<0.05) than the group vaccinated with pRc-VP2 alone as well as the group vaccinated with commercial attenuated IBDV vaccine boosted with commercial oil adjuvanted killed IBDV vaccine. Responsiveness to a mitogenic lectin, phytoheamagglutinin-P was significantly reduced in group immunized with conventional vaccines (live boosted with killed) as compared to all the other groups (P<0.05). The results revealed that co-administration of recombinant plasmids with CpG ODN could protect chickens efficiently from IBDV challenge.

Trp53-dependent DNA-repair is affected by the codon 72 polymorphism

Trp53 is arguably the most critical tumour suppressor gene product that inhibits malignant transformation. Besides mutations that inactivate Trp53 functions, genetic polymorphisms have been suggested to be risk factors for cancer. A polymorphic site at codon 72 in exon 4 encodes either an arginine amino acid (Trp53(72R)) or a proline residue (Trp53(72P)). Previous studies have shown that the Trp53(72R) form is more efficient in apoptosis induction, whereas the Trp53(72P) form was suggested to induce G1 arrest better. Here we report that Trp53(72P) is more efficient than Trp53(72R) in specifically activating several Trp53-dependent DNA-repair target genes in several cellular systems. Moreover, using isogenic cell lines and several DNA-repair assays, we show that Trp53(72P) cells have a significantly higher DNA-repair capacity than the Trp53(72R) cells. Furthermore, Trp53(72P)-expressing cells exhibit reduced micronuclei formation compared to Trp53(72R)-expressing cells, suggesting that genomic instability is reduced in these cells. Together, the data highlight the functional differences between the Trp53 polymorphic variants, and suggest that their expression status may influence cancer risk.