Predictors for a dementia gene mutation based on gene-panel next-generation sequencing of a large dementia referral series

Next-generation genetic sequencing (NGS) technologies facilitate the screening of multiple genes linked to neurodegenerative dementia, but there are few reports about their use in clinical practice. Which patients would most profit from testing, and information on the likelihood of discovery of a causal variant in a clinical syndrome, are conspicuously absent from the literature, mostly for a lack of large-scale studies. We applied a validated NGS dementia panel to 3241 patients with dementia and healthy aged controls; 13,152 variants were classified by likelihood of pathogenicity. We identified 354 deleterious variants (DV, 12.6% of patients); 39 were novel DVs. Age at clinical onset, clinical syndrome and family history each strongly predict the likelihood of finding a DV, but healthcare setting and gender did not. DVs were frequently found in genes not usually associated with the clinical syndrome. Patients recruited from primary referral centres were compared with those seen at higher-level research centres and a national clinical neurogenetic laboratory; rates of discovery were comparable, making selection bias unlikely and the results generalisable to clinical practice. We estimated penetrance of DVs using large-scale online genomic population databases and found 71 with evidence of reduced penetrance. Two DVs in the same patient were found more frequently than expected. These data should provide a basis for more informed counselling and clinical decision making.

Abstract 2055: A first-in-class hemoglobin-floxuridine conjugate for the treatment of advanced stage liver cancer

Hepatocellular carcinoma (HCC) is the second most common cause of death from cancer worldwide; few treatment options are available, especially for advanced stage disease. Therapure has developed a novel drug delivery platform based upon the attachment of drugs to hemoglobin (Hb) as a means of targeting the liver. TBI 302 is a hemoglobin-drug conjugate (HDC) designed to deliver the anticancer drug floxuridine to the liver to improve treatment for HCC. Systemic toxicity associated with free floxuridine restricts its use to locoregional administration (0.2-0.5 mg/kg/d) via continuous hepatic arterial infusion. Although hepatic arterial infusion of floxuridine can reduce hepatic tumor burden, toxicity from floxuridine and complications associated with direct hepatic infusion pumps can be significant. HDC technology exploits the natural pathway for hemoglobin clearance through the liver to provide selective drug targeting while preserving floxuridine activity following standard intravenous (IV) infusion. In a preclinical efficacy study of TBI 302, mice bearing human liver cancer cell line-derived orthotopic liver tumors received twice-weekly tail vein dosing of saline, 3.7 mg/kg floxuridine, or TBI 302. Following 6 weeks of treatment, 70% of the orthotopically implanted mice treated with 170.5 mg/kg TBI 302 (3.7 mg/kg floxuridine) had no measurable liver tumors, indicating suppression of tumor growth. In contrast, only 30% of mice treated with an equivalent dose of unconjugated floxuridine and 20% of mice treated with saline experienced liver tumor growth suppression. These results demonstrate the capability of the HDC platform to enhance the efficacy of cytotoxics through liver targeting. To establish a safe starting dose for a first-in-human Phase 1 trial, a GLP-compliant repeat dose preclinical safety study of TBI 302 in cynomolgus monkeys was conducted. TBI 302 administered by 1-hour IV infusion once per week for 8 weeks at doses of 2, 5, and 10.5 mg/kg (0.08, 0.19, and 0.4 mg/kg floxuridine, respectively) was well tolerated at all dose levels. Increasing doses of TBI 302 resulted in proportional increases in area under the concentration-time curve (AUC) and maximum concentration (Cmax) of total plasma floxuridine. No clinical signs or biochemical toxicity was associated with IV infusion of TBI 302. The no-observed-adverse effect level (NOAEL) of TBI 302 was determined to be the highest dose level of 10.5 mg/kg (0.4 mg/kg floxuridine). A Phase I safety study of TBI 302 as second-line therapy in HCC has been approved by the FDA. The primary objective is to determine safety and tolerability of TBI 302. Secondary objectives are to determine TBI 302 pharmacokinetics and effects on tumor burden. Therapure's HDC platform represents a new class of therapy that offers liver-specific targeting, while potentially reducing extra-hepatic toxicity of drugs.

Citation Format: Steve Brookes, Murray J. Cutler, Jin Seog Seo, Gord Adamson, David Bell. A first-in-class hemoglobin-floxuridine conjugate for the treatment of advanced stage liver cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2055.

Cannabis use and psychosis: re-visiting the role of childhood trauma

BACKGROUND

Cannabis consumption continues to be identified as a causal agent in the onset and development of psychosis. However, recent findings have shown that the effect of cannabis on psychosis may be moderated by childhood traumatic experiences.

METHOD

Using hierarchical multivariate logistic analyses the current study examined both the independent effect of cannabis consumption on psychosis diagnosis and the combined effect of cannabis consumption and childhood sexual abuse on psychosis diagnosis using data from the Adult Psychiatric Morbidity Survey 2007 (n=7403).

RESULTS

Findings suggested that cannabis consumption was predictive of psychosis diagnosis in a bivariate model; however, when estimated within a multivariate model that included childhood sexual abuse, the effect of cannabis use was attenuated and was not statistically significant. The multivariate analysis revealed that those who had experienced non-consensual sex in childhood were over six times [odds ratio (OR) 6.10] more likely to have had a diagnosis of psychosis compared with those who had not experienced this trauma. There was also a significant interaction. Individuals with a history of non-consensual sexual experience and cannabis consumption were over seven times more likely (OR 7.84) to have been diagnosed with psychosis compared with those without these experiences; however, this finding must be interpreted with caution as it emerged within an overall analytical step which was non-significant.

CONCLUSIONS

Future studies examining the effect of cannabis consumption on psychosis should adjust analyses for childhood trauma. Childhood trauma may advance existing gene-environment conceptualisations of the cannabis-psychosis link.

Association of a null allele of SPRN with variant Creutzfeldt-Jakob disease

Background:

No susceptibility genes have been identified in human prion disase, apart from the prion protein gene (PRNP). The gene SPRN, encodes Shadoo (Sho, shadow of prion protein) which has protein homology and possible functional links with the prion protein.

Methods:

A genetic screen was carried out of the open reading frame of SPRN by direct sequencing in 522 patients with prion disease, including 107 with variant Creutzfeldt–Jakob disease (vCJD), and 861 healthy controls.

Results:

A common coding variant of SPRN, two further single nucleotide polymorphisms (SNPs) and three rare insertion or deletion variants were found. A single base-pair insertion at codon 46, predicted to cause a frameshift and potentially a novel protein, was found in two patients with vCJD but not in controls (p = 0.01). Two linked SNPs, one in intron 1 and the other a missense variant at codon 7, were associated with risk of sporadic CJD (p = 0.009).

Conclusion:

These data justify the functional genetic characterisation of SPRN and support the involvement of Shadoo in prion pathobiology.

Phenotypic heterogeneity and genetic modification of P102L inherited prion disease in an international series

The largest kindred with inherited prion disease P102L, historically Gerstmann-Sträussler-Scheinker syndrome, originates from central England, with émigrés now resident in various parts of the English-speaking world. We have collected data from 84 patients in the large UK kindred and numerous small unrelated pedigrees to investigate phenotypic heterogeneity and modifying factors. This collection represents by far the largest series of P102L patients so far reported. Microsatellite and genealogical analyses of eight separate European kindreds support multiple distinct mutational events at a cytosine-phosphate diester-guanidine dinucleotide mutation hot spot. All of the smaller P102L kindreds were linked to polymorphic human prion protein gene codon 129M and were not connected by genealogy or microsatellite haplotype background to the large kindred or each other. While many present with classical Gerstmann-Sträussler-Scheinker syndrome, a slowly progressive cerebellar ataxia with later onset cognitive impairment, there is remarkable heterogeneity. A subset of patients present with prominent cognitive and psychiatric features and some have met diagnostic criteria for sporadic Creutzfeldt-Jakob disease. We show that polymorphic human prion protein gene codon 129 modifies age at onset: the earliest eight clinical onsets were all MM homozygotes and overall age at onset was 7 years earlier for MM compared with MV heterozygotes (P = 0.02). Unexpectedly, apolipoprotein E4 carriers have a delayed age of onset by 10 years (P = 0.02). We found a preponderance of female patients compared with males (54 females versus 30 males, P = 0.01), which probably relates to ascertainment bias. However, these modifiers had no impact on a semi-quantitative pathological phenotype in 10 autopsied patients. These data allow an appreciation of the range of clinical phenotype, modern imaging and molecular investigation and should inform genetic counselling of at-risk individuals, with the identification of two genetic modifiers.

The Novel Hemoglobin-based Oxygen Carrier HRC 101 Improves Survival in Murine Sickle Cell Disease

Background

Erythrocyte transfusion decreases morbidity in sickle cell disease, but is not without risk. Use of a hemoglobin-based oxygen carrier could offer the benefits of erythrocyte transfusion while reducing related complications. The authors tested the hypothesis that the novel hemoglobin-based oxygen carrier, HRC 101, would improve survival during exposure to acute hypoxia in a murine model of sickle cell disease, the transgenic mouse expressing hemoglobin SAD (alpha2beta2).

Methods

Wild-type (n = 30) and transgenic SAD (n = 36) mice received 0.02 ml/g HRC 101 (hemoglobin concentration, 10 g/dl) or an equal volume of 5% albumin. Thirty percent or 6% oxygen was administered to spontaneously breathing mice during halothane anesthesia (inspired concentration, 0.5%). The time to cessation of cardiac electrical activity was recorded. Survival was compared using Kaplan-Meier analysis.

Results

Control mice survived the 60-min study period, whether breathing 30% or 6% oxygen. In contrast, all SAD mice given albumin and 6% oxygen died, with a median survival time of 9.0 min (interquartile range, 6.9-11.6 min; P < 0.0001). HRC 101 significantly increased survival in SAD mice breathing 6% oxygen. Of 12 SAD mice given HRC 101 and 6% oxygen, 4 survived the entire study period and 8 died, with a median survival time of 48 min (19-60 min; P < 0.0001 vs. albumin).

Conclusion

HRC 101 significantly decreased sickle-related mortality during exposure to acute hypoxic stress in transgenic mice expressing hemoglobin SAD. HRC 101 warrants further evaluation as a therapeutic modality in sickle cell disease.

Synthesis and characterization of a hemoglobin-ribavirin conjugate for targeted drug delivery

A novel conjugate of human hemoglobin (Hb) and the nucleoside analogue ribavirin (RBV) was synthesized to demonstrate the utility of Hb as a biocompatible drug carrier for improved drug delivery in the treatment of liver disease. RBV is used in combination with interferon for the treatment of hepatitis C, but its side effects can result in dose limitation or discontinuation of treatment. Targeted delivery of RBV may help to prevent or minimize its toxicity. The hemoglobin-ribavirin conjugate (Hb-RBV) was designed to release bioactive drug upon endocytosis by cells and tissues involved in extracellular Hb catabolism and clearance. Ribavirin-5'-monophosphate (RBV-P) was prepared from RBV and activated as the 5'-monophosphorimidazolide (RBV-P-Im) for reaction with carbonmonoxyhemoglobin to yield Hb-RBV consisting of multiple RBV drugs covalently attached as physiologically labile phosphoramidates via their 5'-hydroxyl groups. A molar drug ratio of six to eight RBV molecules per Hb tetramer was obtained with near complete haptoglobin (Hp) binding of the drug modified Hb maintained. The conjugate complex (Hp-Hb-RBV) was selectively taken up in vitro by cells that express the hemoglobin-haptoglobin receptor, CD163. Recovered ribavirin enzymatically cleaved from Hb-RBV showed equipotent antiproliferative activity compared to control unconjugated RBV against human HepG2 and mouse AML12 liver cell lines. Based upon the reported high level of Hb uptake in the liver, Hb-RBV may be useful in the treatment of certain liver diseases, as well as inflammatory disorders associated with CD163-positive macrophages.

Targeted delivery of ribavirin improves outcome of murine viral fulminant hepatitis via enhanced anti-viral activity

Side effects of interferon-ribavirin combination therapy limit the sustained viral response achievable in hepatitis C virus (HCV) patients. Coupling ribavirin to macromolecular carriers that target the drug to the liver would reduce systemic complications. The aim of this study was to evaluate the efficacy of a hemoglobin-ribavirin conjugate (HRC 203) in murine hepatitis virus strain 3 (MHV-3) induced viral hepatitis. HRC 203 had greater anti-viral activity on both isolated hepatocytes and macrophages, whereas both ribavirin and HRC 203 inhibited production of the pro-inflammatory cytokines interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) by macrophages. In vivo, untreated MHV-3-infected mice all developed clinical and biochemical signs of acute viral hepatitis and died by day 4 post infection. Livers recovered from untreated infected mice showed greater than 90% necrosis. In contrast, survival was enhanced in both ribavirin- and HRC 203-treated mice with a marked reduction in biochemical [ALT(max) 964 +/- 128 IU/L (ribavirin); 848 +/- 212 IU/L (HRC 203)] and histological evidence of hepatic necrosis (<10% in ribavirin/HRC 203 vs. 90% in untreated controls). Clinically, HRC 203-treated mice behaved normally, in contrast to ribavirin-treated mice, which developed lethargy and abnormal fur texture. In conclusion, targeted delivery of ribavirin to the liver alters the course of MHV-3 infection as demonstrated by prolonged survival, improved behavior, and reduced signs of histologically evident disease, as well as inhibition of viral replication and production of inflammatory cytokines in vitro.

Biomedical applications of optical imaging

Developments in imaging offer real-time visualisation of biological processes at the cellular and molecular level. This article considers how micro- and nanotechnology may enhance the application of optical imaging for in vivo and in vitro diagnostics.

Rho and rho kinase modulation of barrier properties: cultured endothelial cells and intact microvessels of rats and mice

Previous experiments using cultured endothelial monolayers indicate that Rho-family small GTPases are involved in modulation of endothelial monolayer permeability by regulating assembly of the cellular actin filament scaffold, activity of myosin-based contractility and junctional distribution of the Ca2+-dependent endothelial cell adhesion molecule, VE-cadherin. We investigated these mechanisms using both cultured endothelial cells (from porcine pulmonary artery and mouse heart) and vascular endothelium in situ (mouse aorta, and individually perfused venular microvessels of mouse and rat mesentery). Exposure to Clostridium difficile toxin B (100 ng x ml(-1)) inactivated 50-90% of all endothelial Rho proteins within 60-90 min. This was accompanied by considerable reduction of actin filament stress fibres and junctional F-actin in cultured endothelial monolayers and in mouse aortic endothelium in situ. Also, VE-cadherin became discontinuous along endothelial junctions. Inhibition of Rho kinase with Y-27632 (30 microM) for 90-120 min induced F-actin reduction both in vitro and in situ but did not cause redistribution or reduction of VE-cadherin staining. Perfusion of microvessels with toxin B increased basal hydraulic permeability (L(p)) but did not attenuate the transient increase in L(p) of microvessels exposed to bradykinin. Perfusion of microvessels with Y-27632 (30 microM) for up to 100 min reduced basal L(p) but did not attenuate the permeability increase induced by platelet activating factor (PAF) or bradykinin. These results show that toxin B-mediated reduction of endothelial barrier properties is due to inactivation of small GTPases other than RhoA. Rho proteins as well as RhoA-mediated contractile mechanisms are not involved in bradykinin- or PAF-induced hyperpermeability of intact microvessels.

An evaluation of the factor structure and predictive utility of a test anxiety scale with reference to students' past performance and personality indices

BACKGROUND

Scales of test anxiety have developed in parallel with the evolution of the test anxiety construct. A recently refined version of the Revised Test Anxiety scale offers the prospect of independently assessing different test anxiety factors.

AIMS

The study aims to ascertain if the four-factor structure of the RTA scale found in Egyptian and American samples can be replicated in an Irish sample, and to examine the comparative predictive utility of cognitive and emotionality factors in relation to examination performance. The study also examines whether results support an Interference or Deficits Model of test anxiety, and assesses the relationship of test anxiety to personality variables believed to be relevant to academic performance.

SAMPLE

The participants were 117 male and female psychology students from the University of Ulster. Their average age was 23 years.

METHOD

Data were analysed using correlation analysis, multiple regression, factor analysis and ANOVA. Examination performance was the criterion variable; predictor variables were the four factors of test anxiety, three personality measures and previous examination performance.

RESULTS

Four-factor test anxiety invariance across diverse population is supported by the model in the analysis. Cognitive factors are significant negative predictors of performance. The data do not support either an Interference or Deficits Model of test anxiety, and personality factors, especially self-efficacy, were significantly (negatively) related to test anxiety.

CONCLUSIONS

The two cognitive factors have emerged as the most substantial negative predictors of examination performance. Attention to these factors and to relevant personality indices are commended as a potentially fruitful strategy for remedial intervention.

Effect of modifying O2 diffusivity and delivery on glomerular and tubular function in hypoxic perfused kidney

Is O2 diffusivity within renal capillaries rate limiting for O2 delivery to hypoxic renal tubules? Equations based on diffusion theory and developed here predict that soluble hemoglobin (Hb) increases O2 diffusivity by a factor of 1 + [442 Hb%/(P50 + PO2)], where P50 is the partial pressure of O2 at which the Hb is half saturated. To examine the effect of P50 and Hb concentrations on renal function, we perfused isolated rat kidneys with Hb-P35 (P50 = 35 mmHg) and Hb-P11 (P50 = 11 mmHg). Venous PO2 was lower with Hb-P11 (10 +/- 1 vs 16 +/- 1 mmHg with arterial PO2 = 35 mmHg and 28 +/- 2 vs. 40 +/- 2 mmHg with arterial PO2 = 140 mmHg; P < 0.001). Perfusate P50 did not influence vascular resistance, glomerular filtration rate, O2 consumption, Na reabsorption, protein excretion, or free water clearance. Percent glucose and phosphate excretion were lower with Hb-P11 than with Hb-P35 (P < 0.001). Urine glucose was 0.17 mmol/l with Hb-P11 and 0.77 mmol/l with Hb-P35 (P < 0.001). Hb-P35 (2%) doubled O2 delivery and lowered glucose and phosphate excretion to the level obtained with 1% Hb-P11. Thus Hb-P11 delivered O2 twice as effectively as Hb-P35 to high-affinity sodium glucose and phosphate cotransporters in the late proximal tubule (S3 segment). Hb-P11 may also have shunted O2 from the outer cortex to the outer medulla and facilitated O2 diffusion where PO2 was low. We conclude that diffusivity is a limiting factor in delivery of O2 to hypoxic tubules.

The in vitro production of antibodies to mitochondrial antigens by peripheral blood mononuclear cells from patients with primary biliary cirrhosis

Peripheral blood mononuclear cells from 7 patients with primary biliary cirrhosis and 7 healthy control subjects were studied for their ability to produce antibodies to mitochondrial antigens in vitro. Peripheral blood mononuclear cells were collected by lymphapheresis and cultured with or without pokeweed mitogen for 10 days. The culture supernatants were then tested for antibodies to mitochondrial antigens by both immunofluorescence microscopy and a microtiter ELISA. Peripheral blood mononuclear cells from 5 of 7 patients with primary biliary cirrhosis but from none of the healthy controls produced antibodies to mitochondrial antigens spontaneously (without pokeweed mitogen stimulation). In contrast, peripheral blood mononuclear cells from 6 of 7 patients with primary biliary cirrhosis and from 6 of 7 control subjects synthesized detectable levels of antibodies to mitochondrial antigens after stimulation with pokeweed mitogen. In general, peripheral blood mononuclear cells from the primary biliary cirrhosis patients produced higher titers of antibodies to mitochondrial antigens in culture than cells from healthy controls. Furthermore, the antibodies to mitochondrial antigens reactivity produced by peripheral blood mononuclear cells of primary biliary cirrhosis patients exhibited a specificity for the M2 mitochondrial antigen which is present on the inner membrane of mitochondrial cristae and which is closely associated with a mitochondrial ATPase activity. In contrast, the antibodies to mitochondrial antigens reactivity produced by peripheral blood mononuclear cells of healthy controls appeared to be directed at a broader range of mitochondrial antigens. These findings indicate that, inpatients with primary biliary cirrhosis, there is a marked expansion of B lymphocyte clones that produce an antibody to a specific mitochondrial antigen.