JS07.5.A 18F-fluciclovine PET and multi-parametric MRI to distinguish pseudoprogression from tumor progression in post-treatment glioblastoma

Background

Differentiation of tumor progression (TP) from pseudoprogression (PsP) is a major unmet need in glioblastoma (GBM). 18F-Fluciclovine is a synthetic amino acid PET radiotracer with higher uptake in tumor tissue vs. areas of treatment-related change. We aimed to assess the combined value of 18F-Fluciclovine PET and multi-parametric MRI for differentiating PsP from TP.

Material and Methods

We enrolled 30 patients with GBM with a new or enlarging contrast-enhancing lesion on MRI after chemoradiotherapy who were planned for surgical resection of the lesion. Patients underwent pre-operative 18F-Fluciclovine PET and multi-parametric MRI. Following surgery, the relative percentages of viable tumor and therapy-related changes observed on histopathology were quantified. Patients were categorized as TP if viable tumor represented ≥ 50% of the specimen, mixed TP if < 50% and > 10%, and PsP if ≤ 10%. SUVmax, SUVpeak, and 50% threshold SUVmean were calculated and normalized to contralateral brain, pituitary gland, and superior sagittal sinus (SSS). The least absolute shrinkage and selection operator (LASSO) was used to determine the variables most predictive of tumor percentage. The strength of association between the primary outcome and selected variables was assessed by Pearson’s or Point-biserial correlation.

Results

18 patients with TP, 4 with mixed TP-PsP, and 8 with PsP were included. There was a positive correlation between 50% threshold SUV mean measured from PET images acquired 50-60 minutes post-injection and rCBVmax by MRI and tumor percentage by histology (r= 0.56; p= 0.004 and r=0.50; p=0.012 respectively). 40-50 minutes SUVmax (OR=1.78 rpb=0.51) and rCBVmax (OR=1.64, rpb=0.48) were positively correlated with tumor TP/mixed TP group. Patients who demonstrated TP/mixed TP-PsP had significantly higher 40-50 minutes SUVmax compared to patients with histological PsP (6.71±2.03 vs 3.93±1.63; p=0.012). 40-50 minutes SUVmax cut-off of 4.46 provided 90% sensitivity and 80% specificity for differentiation of TP/mixed TP-PsP from PsP (AUC=0.88). Combining a 40-50 minutes SUVmax cut-off of 4.46 and an rCBVmax cut-off of 3.67 provided 100% sensitivity and 100% specificity for differentiating TP/mixed TP-PsP from PsP (AUC=1). Patients who demonstrated TP had a significantly higher 40-50 minutes SUVmax compared to patients with histological PsP (6.99±2.06 vs 3.93±1.63; p=0.008). A 40-50 minutes SUVmax cut-off of 4.66 provided 94% sensitivity and 80% specificity for differentiation of TP from PsP (AUC=0.89).

Conclusion

18F-Fluciclovine PET uptake is positively correlated with viable tumor quantification on histology and can accurately differentiate PsP from TP in patients with GBM. Further independent studies are required to cross-validate these promising early results.

Cross-reactivity of antibodies to different rumen methanogens demonstrated using immunomagnetic capture technology

Methane is produced in the rumen of ruminant livestock by methanogens, accounting for approximately 14.5% of anthropogenic greenhouse gas emissions in terms of global warming potential. The rumen contains a diversity of methanogens species, and only a few of these have been cultured. Immunomagnetic capture technology (ICT) is a simple and effective method to capture and concentrate target organisms in samples containing complex microflora. We hypothesized that antibody-coated magnetic beads could be used to demonstrate antibody specificity and cross-reactivity to methanogens in rumen samples. Sheep polyclonal antibodies raised against four isolates of rumen dwelling methanogens, Methanobrevibacter ruminantium strain M1, Methanobrevibacter sp. AbM4, Methanobrevibacter sp. D5, and Methanobrevibacter sp. SM9 or an equal mix of all four isolates, were used to coat paramagnetic beads. ICT was used together with flow cytometry and qPCR to optimize key parameters: the ratio of antibody to beads, coupling time between antibody and paramagnetic beads to produce immunomagnetic beads (IMBs), and optimal incubation time for the capture of methanogen cells by IMBs. Under optimized conditions, IMBs bound strongly to their respective isolates and showed a degree of cross-reactivity with isolates of other Methanobrevibacter spp. in buffer and in rumen fluid, and with resident methanogens in rumen content samples. The evidence provided here indicates that this method can be used to study the interaction of antibodies with antigens of rumen methanogens, to understand antigen cross-reactivity and antibody binding efficiency for the evaluation of antigens used for the development of a broad-spectrum anti-methanogen vaccine for the abatement of methane production.

iRFP (near-infrared fluorescent protein) imaging of subcutaneous and deep tissue tumours in mice highlights differences between imaging platforms

BACKGROUND

In vivo imaging using fluorescence is used in cancer biology for the detection, measurement and monitoring of tumours. This can be achieved with the expression of fluorescent proteins such as iRFP, which emits light at a wavelength less attenuated in biological tissues compared to light emitted by other fluorescent proteins such as GFP or RFP. Imaging platforms capable of detecting fluorescent tumours in small animals have been developed but studies comparing the performance of these platforms are scarce.

RESULTS

Through access to three platforms from Xenogen, Bruker and Li-Cor, we compared their ability to detect iRFP-expressing subcutaneous tumours as well as tumours localised deeper within the body of female NSG mice. Each platform was paired with proprietary software for image analyse, but the output depends on subjective decisions from the user. To more objectively compare platforms, we developed an 'in house' software-based approach which results in lower measured variability between mice.

CONCLUSIONS

Our comparisons showed that all three platforms allowed for reliable detection and monitoring of subcutaneous iRFP tumour growth. The biggest differences between platforms became apparent when imaging deeper tumours with the Li-Cor platform detecting most tumours and showing the highest dynamic range.

Talking to adolescents about alcohol, drugs and sexuality

A discussion of alcohol, drugs and sexuality is an important part of routine health advice and guidance for adolescents. It is important for providers to use a systematic approach that includes building rapport and asking standard screening questions using non-judgmental and gender-neutral language. This strategy minimizes the chance of omitting key questions and increases efficiency of the interview, while being respectful of the adolescent's autonomy and choices. During adolescence, some of the health visit will occur with the adolescent alone. As part of that transition, clinicians should explain conditional confidentiality to both the adolescent and the parent. When discussing alcohol and drug use, clinicians should have information about the epidemiologic patterns in their practice area, use standard tools for screening and be familiar with local resources for treatment. Similarly, when discussing sexuality, clinicians should use a standard approach such as the "5 P's." Clinicians can provide adolescents with a safe environment to share sensitive information and risk taking behaviors using a clear and consistent approach.

Promotion of prostatic metastatic migration towards human bone marrow stoma by Omega 6 and its inhibition by Omega 3 PUFAs

Epidemiological studies have shown not only a relationship between the intake of dietary lipids and an increased risk of developing metastatic prostate cancer, but also the type of lipid intake that influences the risk of metastatic prostate cancer. The Omega-6 poly-unsaturated fatty acid, Arachidonic acid, has been shown to enhance the proliferation of malignant prostate epithelial cells and increase the risk of advanced prostate cancer. However, its role in potentiating the migration of cancer cells is unknown. Here we show that arachidonic acid at concentrations ⩽5 μM is a potent stimulator of malignant epithelial cellular invasion, which is able to restore invasion toward hydrocortisone-deprived adipocyte-free human bone marrow stroma completely. This observed invasion is mediated by the arachidonic acid metabolite prostaglandin E₂ and is inhibited by the Omega-3 poly-unsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid at a ratio of 1 : 2 Omega-3 : Omega-6, and by the COX-2 inhibitor NS-398. These results identify a mechanism by which arachidonic acid may potentiate the risk of metastatic migration and secondary implantation in vivo, a risk which can be reduced with the uptake of Omega-3 poly-unsaturated fatty acids.

Invasive characteristics of human prostatic epithelial cells: understanding the metastatic process

Prostate cancer has a predilection to metastasise to the bone marrow stroma (BMS) by an as yet uncharacterised mechanism. We have defined a series of coculture models of invasion, which simulate the blood/BMS boundary and allow the elucidation of the signalling and mechanics of trans-endothelial migration within the complex bone marrow environment. Confocal microscopy shows that prostate epithelial cells bind specifically to bone marrow endothelial-to-endothelial cell junctions and initiate endothelial cell retraction. Trans-endothelial migration proceeds via an epithelial cell pseudopodial process, with complete epithelial migration occurring after 232±43 min. Stromal-derived factor-1 (SDF-1)/CXCR4 signalling induced PC-3 to invade across a basement membrane although the level of invasion was 3.5-fold less than invasion towards BMS (P=0.0007) or bone marrow endothelial cells (P=0.004). Maximal SDF-1 signalling of invasion was completely inhibited by 10 μM of the SDF-1 inhibitor T140. However, 10 μM T140 only reduced invasion towards BMS and bone marrow endothelial cells by 59% (P=0.001) and 29% (P=0.011), respectively. This study highlights the need to examine the potential roles of signalling molecules and/or inhibitors, not just in single-cell models but in coculture models that mimic the complex environment of the bone marrow.

Role of proteolytic enzymes in human prostate bone metastasis formation: in vivo and in vitro studies

Prostate cancers ability to invade and grow in bone marrow stroma is thought to be due in part to degradative enzymes. The formation of prostate skeletal metastases have been reproduced in vitro by growing co-cultures of prostatic epithelial cells in bone marrow stroma. Expression of urokinase plasminogen activator, matrix metalloproteinase 1 and 7 by prostatic epithelial cells were identified using immunocytochemistry. Also, in vivo tissue sections from human prostatic bone marrow metastases were stained. To establish the role of these enzymes on colony formation, inhibitory antibodies directed against urokinase plasminogen activator, matrix metalloproteinase 1 and matrix metalloproteinase 7 were added into primary prostatic epithelial cells and bone marrow stroma co-cultures. All prostatic epithelial cell cultures stained positively for matrix metalloproteinase 1, matrix metalloproteinase 7 and urokinase plasminogen activator. Generally prostatic epithelial cells derived from malignant tissues showed increased staining in comparison to epithelia derived from non-malignant tissue. In agreement with in vitro co-cultures, the in vivo tissue sections of prostate bone marrow metastases showed positive staining for all three enzymes. Inhibition studies demonstrated that blocking matrix metalloproteinase 1, matrix metalloproteinase 7 and urokinase plasminogen activator function reduced the median epithelial colony area significantly in bone marrow stroma co-cultures in vitro. Using a human ex-vivo model we have shown that matrix metalloproteinase 1, matrix metalloproteinase 7 and urokinase plasminogen activator play an important role in the establishment of prostatic epithelial cells within bone marrow.

Desmosomes are reduced in the mouse uterine luminal epithelium during the preimplantation period of pregnancy: a mechanism for facilitation of implantation

Dynamic regulation of intercellular junctions is an essential aspect of many developmental, reproductive, and physiological processes. We have shown that expression of the desmosomal protein desmoplakin decreases in the luminal uterine epithelium during the preimplantation period of pregnancy in mice. By the time of implantation (between Days 4.5 and 5 of pregnancy), desmoplakin protein can barely be detected by SDS-PAGE and Western blotting, and by immunocytochemistry, it is restricted to well-spaced, punctate dots at the apicolateral junction. Using confocal XZ series and electron microscope quantitation, both the density and distribution of desmosomes along the lateral cell surfaces of luminal epithelial cells were observed to change during early pregnancy. On Day 1 of pregnancy, desmosomes were found at high density in the apicolateral junctional complex, being present here in 79% of ultrathin sections examined, whereas on Day 5, the density was much reduced (present in only 18% of ultrathin sections examined). Desmosomes were found along the lateral surfaces, at or below the level of the nucleus, in 15% of ultrathin sections examined on Day 1 of pregnancy but in only 1% on Day 5. Desmoplakin mRNA declined during the first 4-5 days of pregnancy, along with the protein, suggesting that these changes are controlled at the level of mRNA. This study shows that desmosomes are regulated during early pregnancy, and we propose that a reduction in desmosome adhesion facilitates penetration of the luminal epithelium by trophoblast cells at implantation.

Ran alters nuclear pore complex conformation

Transport across the nuclear membranes occurs through the nuclear pore complex (NPC), and is mediated by soluble transport factors including Ran, a small GTPase that is generally GDP-bound during import and GTP-bound for export. The dynamic nature of the NPC structure suggests a possible active role for it in driving translocation. Here we show that RanGTP but not RanGDP causes alterations of NPC structure when injected into the cytoplasm of Xenopus oocytes, including compaction of the NPC and extension of the cytoplasmic filaments. RanGTP caused accumulation of nucleoplasmin-gold along the length of extended cytoplasmic filaments, whereas RanGDP caused accumulation around the cytoplasmic rim of the NPC. This suggests a possible role for Ran in altering the conformation of the cytoplasmic filaments during transport.

The nuclear pore complex: mediator of translocation between nucleus and cytoplasm

The enclosure of nuclear contents in eukaryotes means that cells require sites in the boundary that mediate exchange of material between nucleus and cytoplasm. These sites, termed nuclear pore complexes (NPCs), number 100–200 in yeast, a few thousand in mammalian cells and approximately 50 million in the giant nuclei of amphibian oocytes. NPCs are large (125 MDa) macromolecular complexes that comprise 50–100 different proteins in vertebrates. In spite of their size and complex structure, NPCs undergo complete breakdown and reformation at cell division. Transport through NPCs can be rapid (estimated at several hundred molecules/pore/second) and accommodates both passive diffusion of relatively small molecules, and active transport of complexes up to several megadaltons in molecular mass. Each pore can facilitate both import and export. The two processes apparently involve multiple pathways for different cargoes, and their transport signals, transport receptors and adapters, and the molecules (and their regulators) that underpin the transport mechanisms. Over the past few years there has been an increasing interest in the pore complex: structural studies have been followed by elucidation of the biochemical aspects of nuclear import, and subsequent investigations into nuclear export. The current challenge is to understand the interactions between the structural elements of the pore complex and the mechanisms that drive the physical processes of translocation through it.

Centration of donor trephination in human corneal transplantation

PURPOSE

To develop and evaluate a new method to quantify centration of the trephined donor cornea relative to the limbus.

METHODS

After human donor corneas were trephined for penetrating keratoplasty, the remaining corneoscleral discs were stained and subjected to image analysis. The centration of the excised donor cornea relative to the limbus was calculated by measuring their centroids from the "captured" images.

RESULTS

Fifty-two corneoscleral discs were analyzed. The average deviation from the centre was 0.32 mm (SD, 0.18 mm). Neither surgeon nor the type of trephine significantly influenced the mean centroid deviation.

CONCLUSION

We have developed and evaluated a method to quantify centration of human donor cornea. In a small series, decentration did not correlate significantly with either the surgeon or the trephine.

Three dimensional analysis of the retinal vasculature using immunofluorescent staining and confocal laser scanning microscopy

AIM

To undertake a qualitative and quantitative analysis in three dimensions of the human retinal vasculature.

METHOD

Fixed and excised whole retinas were permeabilised and subjected to immunofluorescent staining for blood vessel components followed by confocal laser scanning microscopy. Single projection and stereoimages were constructed using computer software. XZ sections through the retina were constructed and the vasculature analysed using appropriate software.

RESULTS

Immunofluorescent staining with no discontinuities was present in vessels of all sizes, the confocal images of the capillary network being free of out of focus blur at all depths. Quantitative analysis of XZ sections confirmed the qualitative impression of sharp delineation of the deep retinal capillary plexus, an absence of laminar arrangement of capillaries within the inner retina, and a truncated cone of capillaries around the foveal avascular zone (FAZ) wherein the superficial capillaries approached the FAZ more closely than those in the deeper retina.

CONCLUSION

Immunofluorescent staining of the retina and confocal laser scanning microscopy were shown to be useful in analysing accurate three dimensional reconstructions of the normal retinal vasculature without affecting overall tissue architecture.

Relationships between resting and total energy expenditure in injured and septic patients

OBJECTIVE

To quantify resting and total energy expenditure in patients who have suffered severe trauma and sepsis.

DESIGN

Prospective, unblinded, observational, nonrandomized study.

SETTING

Critical care unit of a Level I adult trauma center.

PATIENTS

Immediate posttrauma patients or trauma patients exhibiting signs of sepsis with multiple organ dysfunction.

INTERVENTIONS

An indirect calorimeter was used to measure energy expenditure at rest (resting energy expenditure) at 0700 and 1900 hrs. The energy expenditure measurement was then continued for up to 12 hrs (total energy expenditure). Clinical data were collected for computation of an illness severity score.

RESULTS

Thirteen trauma and 20 septic patients were studied 240 times. All patients were mechanically ventilated. Morphine or fentanyl was infused during 99% of studies. Neuromuscular blocking agents were used in 42% of septic studies. Both the trauma and septic groups were hypermetabolic (mean trauma resting energy expenditure, 36 +/- 6 kcal/kg; mean septic resting energy expenditure, 44 +/- 8 kcal/kg; p < .05). Total energy expenditure was similar to resting energy expenditure (trauma total energy expenditure = resting energy expenditure x 1.035 +/- 0.078, septic total energy expenditure = resting energy expenditure x 1.039 +/- 0.071). Total energy expenditure and resting energy expenditure were linearly related (r2 = .89, p < .0001).

CONCLUSIONS

Trauma and septic patients are hypermetabolic, even when heavily sedated or medically paralyzed. A measurement of resting energy expenditure is a close approximation of total energy expenditure in most patients.

Results of the IPCS collaborative study on complex mixtures

The International Programme on Chemical Safety (IPCS) sponsored a collaborative study to examine the intra- and inter-laboratory variation associated with the preparation and bioassay of complex chemical mixtures. The mixtures selected were National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs). 20 laboratories worldwide participated in the collaborative trial. The participating laboratories extracted the organic portion of two particulate samples--an air-particulate sample and a diesel-particulate sample--and bioassayed the extracts. The laboratories simultaneously bioassayed a NIST-prepared extract of coal tar and two control compounds (benzo[a]pyrene, and 1-nitropyrene). The bioassay method used was the Salmonella/mammalian microsome plate-incorporation test using strains TA98 and TA100. Study design also allowed for a comparison of sonication and Soxhlet extraction techniques. The mean extractable masses for the air particles and diesel particles were approximately 5% and 17.5%, respectively. The particulate samples were mutagenic in both strains with and without activation in all 20 laboratories. For TA100 the with and without activation slope values for the air particulate were 162 and 137 revertants per mg particles, respectively. For TA98 the respective diesel slope values were 268 and 269. The mutagenicity slope values for the diesel particles ranged from 3090 (TA98, +S9) to 6697 (TA100, +S9) revertants per mg particles. The coal tar solution was negative for both strains when exogenous activation was not used but was mutagenic in both strains with exogenous activation. The benzo[a]pyrene and 1-nitropyrene were used as positive controls and gave results consistent with the literature. This paper provides a complete summary of the data collected during the collaborative study. Companion papers provide further analysis and interpretation of the results.

Calmodulin-sensitive and calmodulin-insensitive components of adenylate cyclase activity in rat striatum have differential responsiveness to guanyl nucleotides

The interaction between the Ca2+-binding protein, calmodulin, and guanyl nucleotides was investigated in a rat striatal particulate fraction. We found that the ability of calmodulin to stimulate adenylate cyclase in the presence of guanyl nucleotides depends upon the type and concentration of the guanyl nucleotide. Adenylate cyclase activity measured in the presence of calmodulin and GTP reflected additivity at every concentration of these reactants. On the contrary, when the activating guanyl nucleotide was the nonhydrolyzable analog of GTP, guanosine-5'-(beta,gamma-imido)triphosphate (GppNHp), calmodulin could further activate adenylate cyclase only at concentrations less than 0.2 microM GppNHp. Kinetic analysis of adenylate cyclase by GppNHp was compatible with a model of two components of adenylate cyclase activity, with over a 100-fold difference in sensitivity for GppNHp. The component with the higher affinity for GppNHp was competitively stimulated by calmodulin. The additivity between calmodulin and GTP in the striatal particulate fraction suggests that they stimulate different components of cyclase activity. The calmodulin-stimulatable component constituted 60% of the total activity. Our two-component model does not delineate, at this point, whether there are two separate catalytic subunits or one catalytic subunit with two GTP-binding proteins.(ABSTRACT TRUNCATED AT 250 WORDS)