Assessing the Clinical Utility of Liquid Biopsies Across 5 Potential Indications From Therapy Selection to Population Screening: A Review.

Importance: There has been great enthusiasm for the emerging technology of molecular-based tests to detect and quantify tumor DNA circulating in the bloodstream, colloquially known as a liquid biopsy. However, less attention has been given to how their clinical utility depends on the indication for testing, which includes a range of clinical situations, each presenting unique challenges. Observations: Five indications for circulating tumor DNA (ctDNA) blood testing were considered. (1) For therapy selection, ctDNA tests can identify genetic alterations in patients with cancer amenable to targeted therapy, but most patients do not have a targetable alteration. (2) For response to therapy, the absence of residual tumor DNA following cancer surgery could reduce the use of adjuvant chemotherapy, but it is unclear that this will happen in practice. (3) For disease surveillance following cancer treatment, ctDNA tests may well detect cancer recurrence before symptoms appear, yet earlier intervention may have no effect on mortality. (4) For diagnosis of suspected cancer, ctDNA tests are able to identify some symptomatic cancers, but how they add to the conventional diagnostic evaluation is unknown. (5) For screening for cancer, multicancer tests can detect many types of cancer, but their low sensitivity for early-stage tumors raises questions as to whether screening can help patients live longer or live better. Conclusions and Relevance: Circulating tumor DNA tests are being promoted for multiple indications. Numerous studies are ongoing, but randomized clinical trials of their effect on patient-centered outcomes are rare. While these tests have the potential to improve care in selected indications, this must be proven, as they will add cost, complexity, and unintended adverse effects for patients.

Placental vascularity and markers of angiogenesis in relation to prenatal growth status in overnourished adolescent ewes.

INTRODUCTION: Placental vascularity may be important in the development of fetal growth restriction (FGR). The overnourished adolescent ewe is a robust model of the condition, with ∼50% of offspring demonstrating FGR (birthweight >2 standard deviations below optimally-fed control mean). We studied whether placental vascularity, angiogenesis and glucose transport reflect FGR severity. METHODS: Singleton pregnancies were established in adolescent ewes either overnourished to putatively restrict fetoplacental growth (n = 27) or control-fed (n = 12). At 131d (term = 145d) pregnancies were interrupted and fetuses classified as FGR (n = 17, <4222 g, -2SD below control-fed mean) or non-FGR (n = 10). Placentome capillary area density (CAD), number density (CND), surface density (CSD), and area per capillary (APC) in the fetal cotyledon (COT) and maternal caruncle (CAR) were analysed using immunostaining. COT/CAR mRNA expression of angiogenic ligands/receptors and glucose transporters were measured by qRT-PCR. RESULTS: Fetal weight was reduced in FGR vs. Non-FGR/Control groups. Total placentome weight was Control > Non-FGR > FGR and fetal:placental weight ratios were higher in overnourished versus Control groups. COT vascular indices were Non-FGR > FGR > Control. COT-CAD, CSD and APC were significantly greater in Non-FGR overnourished versus Control and intermediate in FGR groups. CAR vascularity did not differ. CAR-VEGFA/FLT1/KDR/ANGPT1/ANGPT2/SLC2A1/SLC2A3 mRNA was lower and COT-ANGPT2 higher in overnourished versus Control groups. DISCUSSION: Relative to control-intake pregnancy, overnourished pregnancies are characterised by higher COT vascularity, potentially a compensatory response to reduced nutrient supply, reflected by higher fetal:placental weight ratios. Compared with overnourished pregnancies where fetal growth is relatively preserved, overnourished pregnancies culminating in marked FGR have less placental vascularity, suggesting incomplete adaptation to the prenatal insult.

Peri- and Postnatal Effects of Prenatal Adenoviral VEGF Gene Therapy in Growth-Restricted Sheep.

Uterine artery (UtA) adenovirus (Ad) vector-mediated overexpression of vascular endothelial growth factor (VEGF) enhances uterine blood flow in normal sheep pregnancy and increases fetal growth in the overnourished adolescent sheep model of fetal growth restriction (FGR). Herein, we examined its impact on gestation length, neonatal survival, early postnatal growth and metabolism. Singleton-bearing ewes were evenly allocated to receive Ad.VEGF-A165 (5 × 10(10) particles/ml, 10 ml, n = 17) or saline (10 ml, n = 16) injected into each UtA at laparotomy (0.6 gestation). Fetal growth was serially monitored (blind) by ultrasound until delivery. Lambs were weighed and blood was sampled weekly and a glucose tolerance test performed (68-day postnatal age). Hepatic DNA/RNA was extracted at necropsy (83-day postnatal age) to examine methylation status of eight somatotropic axis genes. IGF1 mRNA and protein expression were measured by RT-PCR and radioimmunoassay, respectively. All pregnancies remained viable following Ad.VEGF-A165 treatment. Fetal abdominal circumference and renal volume were greater in the Ad.VEGF-A165 group compared with the saline group at 21/28 days (P ≤ 0.04) postinjection. At delivery, gestation length (P = 0.07), lamb birthweight (P = 0.08), umbilical girth (P = 0.06), and plasma glucose (P = 0.09) tended to be greater in Ad.VEGF-A165-treated lambs. Levels of neonatal intervention required to ensure survival was equivalent between groups. Absolute postnatal growth rate (P = 0.02), insulin area under the curve (P = 0.04) and carcass weight at necropsy (P = 0.04) were increased by Ad.VEGF-A165 treatment. There was no impact on markers of insulin sensitivity or methylation/expression of key genes involved in somatic growth. Ad.VEGF-A165 gene therapy increased fetal growth in a sheep FGR model, and lambs continued to thrive during the neonatal and early postnatal period.

VEGF Gene Transfer to the Utero-Placental Circulation of Pregnant Guinea Pigs to Enhance Fetal Growth.

In this chapter, we describe a novel method of adenoviral gene transfer to the uterine and radial arteries of pregnant guinea pigs to improve fetal growth. Adenoviruses encoding VEGF-A165 or a reporter gene ß-galactosidase were reconstituted in pluronic gel and applied topically to the exposed uterine and radial arteries following laparotomy. Pluronic gel is a thermosensitive gel that is liquid at 4 °C, but becomes solid as soon as it comes in contact with body temperature. It thereby acts as a slow-release vehicle for viral vectors to the target tissue and also facilitates closer contact of the viruses with the host tissue. Our studies have shown that adenoviral gene delivery using pluronic gel resulted in the highest transduction efficiency compared to intra-arterial administration or external administration in PBS as a vehicle, when measured by X-gal staining, immunohistochemistry, or Western blotting.

VEGF Gene Transfer to the Utero-Placental Circulation of Pregnant Sheep to Enhance Fetal Growth.

In this chapter, we describe a safe and effective approach to achieve local VEGF gene transfer to the uterine arteries in pregnant sheep using direct injection of viral vectors into the uterine arteries. This approach resulted in improved fetal growth in growth-restricted pregnancies. Adenoviral vectors encoding VEGF-A165 or a reporter gene ß-galactosidase were dissolved in 10 mL normal saline shortly before administration. A midline laparotomy was performed and the course of the uterine artery identified. The main trunk (just prior to the first bifurcation) was mobilized by dissection and a vessel loop placed beneath it in order to elevate the artery, which was then occluded digitally just proximal to the planned injection site. The adenoviral solution was slowly injected over 1 min, and the occlusion was maintained for a further 4 min to maximize transduction of the downstream endothelium. After ensuring hemostasis, the abdomen was closed in layers.

The arc mutants of Arabidopsis with fewer large chloroplasts have a lower mesophyll conductance.

Photosynthetic cells of most land plant lineages have numerous small chloroplasts even though most algae, and even the early diverging land plant group the hornworts, tend to have one or a few large chloroplasts. One constraint that small chloroplasts could improve is the resistance to CO2 diffusion from the atmosphere to the chloroplast stroma. We examined the mesophyll conductance (inverse of the diffusion resistance) of mutant Arabidopsis thaliana plants with one or only a few large chloroplasts per cell. The accumulation and replication of chloroplasts (arc) mutants of A. thaliana were studied by model fitting to gas exchange data and (13)CO2 discrimination during carbon fixation. The two methods generally agreed, but the value of the CO2 compensation point of Rubisco (Γ *) used in the model had a large impact on the estimated photosynthetic parameters, including mesophyll conductance. We found that having only a few large chloroplasts per cell resulted in a 25-50 % reduction in the mesophyll conductance at ambient CO2.

Uteroplacental adenovirus vascular endothelial growth factor gene therapy increases fetal growth velocity in growth-restricted sheep pregnancies.

Fetal growth restriction (FGR) occurs in ∼8% of pregnancies and is a major cause of perinatal mortality and morbidity. There is no effective treatment. FGR is characterized by reduced uterine blood flow (UBF). In normal sheep pregnancies, local uterine artery (UtA) adenovirus (Ad)-mediated overexpression of vascular endothelial growth factor (VEGF) increases UBF. Herein we evaluated Ad.VEGF therapy in the overnourished adolescent ewe, an experimental paradigm in which reduced UBF from midgestation correlates with reduced lamb birthweight near term. Singleton pregnancies were established using embryo transfer in adolescent ewes subsequently offered a high intake (n=45) or control intake (n=12) of a complete diet to generate FGR or normal fetoplacental growth, respectively. High-intake ewes were randomized midgestation to receive bilateral UtA injections of 5×10¹¹ particles Ad.VEGF-A165 (n=18), control vector Ad.LacZ (n=14), or control saline (n=13). Fetal growth/well-being were evaluated using serial ultrasound. UBF was monitored using indwelling flowprobes until necropsy at 0.9 gestation. Vasorelaxation, neovascularization within the perivascular adventitia, and placental mRNA expression of angiogenic factors/receptors were examined using organ bath analysis, anti-vWF immunohistochemistry, and qRT-PCR, respectively. Ad.VEGF significantly increased ultrasonographic fetal growth velocity at 3-4 weeks postinjection (p=0.016-0.047). At 0.9 gestation fewer fetuses were markedly growth-restricted (birthweight >2SD below contemporaneous control-intake mean) after Ad.VEGF therapy. There was also evidence of mitigated fetal brain sparing (lower biparietal diameter-to-abdominal circumference and brain-to-liver weight ratios). No effects were observed on UBF or neovascularization; however, Ad.VEGF-transduced vessels demonstrated strikingly enhanced vasorelaxation. Placental efficiency (fetal-to-placental weight ratio) and FLT1/KDR mRNA expression were increased in the maternal but not fetal placental compartments, suggesting downstream effects on placental function. Ad.VEGF gene therapy improves fetal growth in a sheep model of FGR, although the precise mechanism of action remains unclear.

Fetoplacental biometry and umbilical artery Doppler velocimetry in the overnourished adolescent model of fetal growth restriction.

OBJECTIVE: The purpose of this study was to evaluate ultrasonographically fetal growth trajectories, placental biometry, and umbilical artery (UA) Doppler indices in growth-restricted pregnancies of overnourished adolescent ewes and normally developing pregnancies of control-fed ewes. STUDY DESIGN: Singleton pregnancies were established using embryo transfer in 42 adolescent ewes that were overnourished (n = 27) or control-fed (n = 15) and were scanned at weekly intervals from 83-126 days' gestation and necropsied at 131 days' gestation (term = 145 days). RESULTS: Ultrasonographic placental measurements were reduced and UA Doppler indices were increased from 83 days' gestation; measurements of fetal abdominal circumference and femur length, renal volume and tibia length, and biparietal diameter were reduced from 98, 105, and 112 days' gestation, respectively, in overnourished vs control-intake pregnancies. CONCLUSION: Overnourishment of adolescent sheep dams produced late-onset asymmetric fetal growth restriction that was commensurate with brain sparing. Ultrasonographic placental biometry was already reduced and UA Doppler indices increased by mid gestation in overnourished pregnancies, preceding reduced fetal growth velocity and indicating an early nutritionally mediated insult on placental development.

Engineering starch accumulation by manipulation of phosphate metabolism of starch.

A new understanding of leaf starch degradation has emerged in the last 10 years. It has been shown that starch phosphorylation and dephosphorylation are critical components of this process. Glucan, water dikinase (GWD) (and phosphoglucan, water dikinase) adds phosphate to starch, and phosphoglucan phosphatase (SEX4) removes these phosphates. To explore the use of this metabolism to manipulate starch accumulation, Arabidopsis (Arabidopsis thaliana) plants were engineered by introducing RNAi constructs designed to reduce expression of AtGWD and AtSEX4. The timing of starch build-up was altered with ethanol-inducible and senescence-induced gene promoters. Ethanol induction of RNAi lines reduced transcript for AtGWD and AtSEX4 by 50%. The transgenic lines had seven times more starch than wild type at the end of the dark period but similar growth rates and total biomass. Elevated leaf starch content in maize leaves was engineered by making an RNAi construct against a gene in maize that appeared to be homologous to AtGWD. The RNAi construct was expressed using the constitutive ubiquitin promoter. Leaf starch content at the end of a night period in engineered maize plants was 20-fold higher than in untransformed plants with no impact on total plant biomass. We conclude that plants can be engineered to accumulate starch in the leaves with little impact on vegetative biomass.

Ultrasonographic assessment of growth and estimation of birthweight in late gestation fetal sheep.

Our aim was to identify which ultrasound parameters can be most accurately measured and best predict ovine fetal weight in late gestation. Singleton pregnancies were established using embryo transfer in 32 adolescent ewes, which were subsequently overnourished to produce fetuses of variable size (1720-6260 g). Ultrasound measurements at 126-133 days gestation were compared with fetal weight/biometry at late-gestation necropsy (n = 19) or term delivery (n = 13). Abdominal circumference (AC) and renal volume (RV) correlated best with physical measurements (r = 0.78-0.83) and necropsy/birth weight (r = 0.79-0.84). Combination of AC + RV produced an estimated fetal weight equation [Log EFW = 2.115 + 0.003 AC + 0.12 RV - 0.005 RV(2)] with highest adjusted R(2) (0.72) and lowest mean absolute/percentage prediction error (396-550 g/11.1%-13.2%). In conclusion, AC and RV are parameters of choice for assessment of late-gestation ovine fetal growth and can be used to estimate fetal weight with similar accuracy to human fetuses.

Fluorescent bio-barcode DNA assay for the detection of Salmonella enterica serovar Enteritidis.

Salmonella enterica serovar Enteritidis is one of the most frequently reported causes of foodborne illness. It is a major threat to the food safety chain and public health. A highly amplified bio-barcode DNA assay for the rapid detection of the insertion element (Iel) gene of Salmonella Enteritidis is reported in this paper. The biosensor transducer is composed of two nanoparticles: gold nanoparticles (Au-NPs) and magnetic nanoparticles (MNPs). The Au-NPs are coated with the target-specific DNA probe which can recognize the target gene, and fluorescein-labeled barcode DNA in a 1:100 probe-to-barcode ratio. The MNPs are coated with the 2nd target-specific DNA probe. After mixing the nanoparticles with the 1st target DNA, the sandwich structure (MNPs-2nd DNA probe/Target DNA/1st DNA probe-Au-NPs-barcode DNA) is formed. A magnetic field is applied to separate the sandwich from the unreacted materials. Then the bio-barcode DNA is released from the Au-NPs. Because the Au-NPs have a large number of barcode DNA per DNA probe binding event, there is substantial amplification. The released barcode DNA is measured by fluorescence. Using this technique, the detection limit of this bio-barcode DNA assay is as low as 2.15 x 10(-16)mol (or 1 ng/mL).

Prediction of hemodialysis sorbent cartridge urea nitrogen capacity and sodium release from in vitro tests.

In sorbent-based hemodialysis, factors limiting a treatment session are urea conversion capacity and sodium release from the cartridge. In vitro experiments were performed to model typical treatment scenarios using various dialyzers and 4 types of SORB sorbent cartridges. The experiments were continued to the point of column saturation with ammonium. The urea nitrogen removed and amount of sodium released in each trial were analyzed in a multi-variable regression against several variables: amount of zirconium phosphate (ZrP), dialysate flow rate (DFR), simulated blood flow rate (BFR), simulated patient whole-body fluid volume (V), initial simulated patient urea concentration (BUNi), dialyzer area permeability (KoA) product, initial dialysate sodium and bicarbonate (HCO3i) concentrations, initial simulated patient sodium (Nai), pH of ZrP, creatinine, breakthrough time, and average urea nitrogen concentration in dialysate. The urea nitrogen capacity (UNC) of various new SORB columns is positively related to ZrP, BFR, V, BUNi, and ZrP pH and negatively to DFR with an R2 adjusted=0.990. Two models are described for sodium release. The first model is related positively to DFR and V and negatively to ZrP, KoA product, and dialysate HCO3i with an R2 adjusted=0.584. The second model incorporates knowledge of initial simulated patient sodium (negative relationship) and urea levels (negative relationship) in addition to the parameters in the first model with an R2 adjusted=0.786. These mathematical models should allow for prediction of patient sodium profiles and the time of column urea saturation based on simple inputs relating to patient chemistries and the dialysis treatment.

Sorbent suspensions vs. sorbent columns for extracorporeal detoxification in hepatic failure.

Hepatic failure is a significant medical problem which has been unsuccessfully treated by hemodialysis. However, similar therapies using recirculated dialysate regenerated by sorbents in place of single-pass dialysate have been beneficial in treating acute-on-chronic liver failure. The advantages of sorbent-based treatments include some selectivity of toxin removal and improved removal of protein-bound toxins. Activated carbon has been extensively used in detoxification systems, but has often had insufficient toxin capacity. Powdered activated carbon, because of its large surface area, can provide greater binding capacity for bilirubin and other toxins than granular carbon commonly used in detoxifying columns. Methods of using powdered carbon in extracorporeal blood treatment devices are reviewed in the present paper, including liver dialysis and a new sorbent suspension reactor (SSR); and the abilities and limitations of the SSR and columns to process protein solutions are discussed.

Predicting dialysate sodium composition in sorbent dialysis using single point and multiple-dilution conductivity measurement.

This research establishes the ability to predict the sodium composition in dialysate from a single conductivity measurement over the wide range of concentrations of chloride, bicarbonate, and acetate that occur during sorbent dialysis. The ranges explored in mEq/L were sodium 100-180, chloride 76-143, bicarbonate 16-31, and acetate 4-11. Through mathematical optimization using a pattern search method, a single point measurement technique was shown to predict the total sodium concentration within approximately +/- 4.2 mEq/L in solutions with varying relative concentrations of chloride, bicarbonate, and acetate. The data analysis showed that the total sodium concentration can be predicted within +/- 2.1 mEq/L in most cases. Another potential approach to determining sodium concentration, a multiple-dilution measurement method, was tested and is also described. It is based on the varying relationship of activity to concentration for each of the sodium-anion pairs. This technique has practical limitations because of interactions between the various ions in solution at normal concentrations of dialysis along with the complexities involved in creating high dilutions of dialysate for on-line assays during dialysis.

Treatment of severe tricyclic antidepressant overdose with extracorporeal sorbent detoxification.

Tricyclic overdose can be a medical emergency, and therapy with intravenous bicarbonate is not always successful in preventing cardiac toxicity or coma. Mortality in patients developing these complications is from 1% to 15%. Extracorporeal detoxification with sorbents has been used in treatment of patients with very high drug levels and declining clinical condition. Ten patients with serious drug overdose caused by tricyclics failed to respond quickly to standard therapy and were in stage 3-4 encephalopathy. Nine of these patients were on respirator support, 5 had hypotension, and 6 had QRS widening. Average level was 1,423 microg/L at presentation. Enteral activated charcoal and intravenous (IV) bicarbonate were initiated in the emergency room. The patients were treated for 3 to 4 hours with the Liver Dialysis Unit, a hemodiabsorption device using a cellulosic plate dialyzer and sorbent suspension as dialysate. Inflow and outflow blood levels indicated that the hemodetoxifier removed modest amounts of the tricyclics, metabolites, and other consumed drugs. The clinical improvement of the patients was dramatic, with patients reaching stage 0 or 1 encephalopathy during the treatment. Ventilator support was removed at the end of treatment for 3 patients who had not already developed pneumonia, and for others was prolonged up to 48 hours because of pneumonia, rather than mental status. Average length of stay in the intensive care unit (ICU) was 4.8 days (range 1 to 7 days). None of the patients died despite their high risk for ventricular arrhythmias, seizures, and death. Clinical improvement may have been attributable to removal of free drug from the blood or to removal of drug metabolites.