Constructing longitudinal disease progression curves using sparse, short-term individual data with an application to Alzheimer's disease

In epidemiology, cohort studies utilised to monitor and assess disease status and progression often result in short-term and sparse follow-up data. Thus, gaining an understanding of the full-term disease pathogenesis can be difficult, requiring shorter-term data from many individuals to be collated. We investigate and evaluate methods to construct and quantify the underlying long-term longitudinal trajectories for disease markers using short-term follow-up data, specifically applied to Alzheimer's disease. We generate individuals' follow-up data to investigate approaches to this problem adopting a four-step modelling approach that (i) determines individual slopes and anchor points for their short-term trajectory, (ii) fits polynomials to these slopes and anchor points, (iii) integrates the reciprocated polynomials and (iv) inverts the resulting curve providing an estimate of the underlying longitudinal trajectory. To alleviate the potential problem of roots of polynomials falling into the region over which we integrate, we propose the use of non-negative polynomials in Step 2. We demonstrate that our approach can construct underlying sigmoidal trajectories from individuals' sparse, short-term follow-up data. Furthermore, to determine an optimal methodology, we consider variations to our modelling approach including contrasting linear mixed effects regression to linear regression in Step 1 and investigating different orders of polynomials in Step 2. Cubic order polynomials provided more accurate results, and there were negligible differences between regression methodologies. We use bootstrap confidence intervals to quantify the variability in our estimates of the underlying longitudinal trajectory and apply these methods to data from the Alzheimer's Disease Neuroimaging Initiative to demonstrate their practical use. Copyright © 2017 John Wiley & Sons, Ltd.

Bipolar cell reduction precedes retinal ganglion neuron loss in a complex 1 knockout mouse model

Inherited mitochondrial complex 1 deficiency causes Leber's hereditary Optic Neuropathy (LHON) and retinal ganglion cell (RGC) degeneration, and optic neuropathies are common in many inherited mitochondrial diseases. How mitochondrial defects pathomechanistically trigger optic neuropathy remains unclear. We observe that complex 1-deficient Ndufs4-/- mice present with acute vision loss around p30, and this vision loss is coincident with an 'inflammatory wave'. In order to understand what causes the inflammatory wave we explored retinal pathology that occurs from p20-p30. The results indicated that in the period p20-p30 in Ndufs4-/- retinas, there is: significant reduction in bipolar cells, RGC dendritic atrophy, reduced PSD95, increased oxidative stress as manifested by increased 4HNE, HO1 and Cuzn-SOD, increased mitochondrial biogenesis and increased apoptosis. These precede the major induction of 'inflammatory wave' at p30 shown previously, but occur earlier than frank RGC loss at p42. In general, complex 1 deficiency in retina triggers oxidative stress and mitochondrial respiratory dysfunction that causes death of the most sensitive cells, including bipolar cells and their synaptic contacts and amacrine cells in the early period, 20-24days. The early death of these cells is the likely precursor to the sharp rise in inflammatory molecules that occurs at day 30 and coincides with vision loss, and greatly precedes the death of RGCs that occurs at p42. These data suggest that metabolic antioxidant support of the most sensitive cells in the retina, or anti-inflammatory suppression of the consequences of their death, are both rational strategies for mitochondrial blinding disease.

Colon wall motility: comparison of novel quantitative semi-automatic measurements using cine MRI

BACKGROUND

Recently, cine magnetic resonance imaging (MRI) has shown promise for visualizing movement of the colonic wall, although assessment of data has been subjective and observer dependent. This study aimed to develop an objective and semi-automatic imaging metric of ascending colonic wall movement, using image registration techniques.

METHODS

Cine balanced turbo field echo MRI images of ascending colonic motility were acquired over 2 min from 23 healthy volunteers (HVs) at baseline and following two different macrogol stimulus drinks (11 HVs drank 1 L and 12 HVs drank 2 L). Motility metrics derived from large scale geometric and small scale pixel movement parameters following image registration were developed using the post ingestion data and compared to observer grading of wall motion. Inter and intra-observer variability in the highest correlating metric was assessed using Bland-Altman analysis calculated from two separate observations on a subset of data.

KEY RESULTS

All the metrics tested showed significant correlation with the observer rating scores. Line analysis (LA) produced the highest correlation coefficient of 0.74 (95% CI: 0.55-0.86), p < 0.001 (Spearman Rho). Bland-Altman analysis of the inter- and intra-observer variability for the LA metric, showed almost zero bias and small limits of agreement between observations (-0.039 to 0.052 intra-observer and -0.051 to 0.054 inter-observer, range of measurement 0-0.353).

CONCLUSIONS & INFERENCES

The LA index of colonic motility derived from cine MRI registered data provides a quick, accurate and non-invasive method to detect wall motion within the ascending colon following a colonic stimulus in the form of a macrogol drink.

The national incidence and clinical picture of SLE in children in Australia – a report from the Australian Paediatric Surveillance Unit

Objectives

The objectives of this paper are to prospectively determine the incidence of paediatric systemic lupus erythematosus (pSLE) in Australia as well as describe the demographics, clinical presentation and one-year outcome.

Study design

Newly diagnosed cases of pSLE were ascertained prospectively from October 2009 to October 2011 through the Australian Paediatric Surveillance Unit (a national monthly surveillance scheme for notification of childhood rare diseases) as well as national subspecialty groups. Questionnaires were sent to notifying physicians at presentation and at one year.

Results

The annual incidence rate was 0.32 per 105 children aged less than 16 years. The incidence was significantly higher in children of Asian or Australian Aboriginal and Torres Strait Islander parents. Approximately one-third of children underwent a renal biopsy at presentation and 7% required dialysis initially although only one child had end-stage kidney disease (ESKD) at one-year follow-up.

Conclusion

The incidence of pSLE in Australia is comparable to that worldwide with a significantly higher incidence seen in children of Asian and Australian Aboriginal and Torres Strait Islander backgrounds. Renal involvement is common but progression to ESKD, at least in the short term, is rare.

Stimulation of colonic motility by oral PEG electrolyte bowel preparation assessed by MRI: comparison of split vs single dose

BACKGROUND

Most methods of assessing colonic motility are poorly acceptable to patients. Magnetic resonance imaging (MRI) can monitor gastrointestinal motility and fluid distributions. We predicted that a dose of oral polyethylene glycol (PEG) and electrolyte solution would increase ileo-colonic inflow and stimulate colonic motility. We aimed to investigate the colonic response to distension by oral PEG electrolyte in healthy volunteers (HVs) and to evaluate the effect of single 2 L vs split (2 × 1 L) dosing.

METHODS

Twelve HVs received a split dose (1 L the evening before and 1 L on the study day) and another 12 HVs a single dose (2 L on the main study day) of PEG electrolyte. They underwent MRI scans, completed symptom questionnaires, and provided stool samples. Outcomes included small bowel water content, ascending colon motility index, and regional colonic volumes.

KEY RESULTS

Small bowel water content increased fourfold from baseline after ingesting both split (p = 0.0010) and single dose (p = 0.0005). The total colonic volume increase from baseline was smaller for the split dose at 35 ± 8% than for the single dose at 102 ± 27%, p = 0.0332. The ascending colon motility index after treatment was twofold higher for the single dose group (p = 0.0103).

CONCLUSIONS & INFERENCES

Ingestion of 1 and 2 L PEG electrolyte solution caused a rapid increase in the small bowel and colonic volumes and a robust rise in colonic motility. The increase in both volumes and motility was dose dependent. Such a challenge, being well-tolerated, could be a useful way of assessing colonic motility in future studies.

A validated bowel-preparation tolerability questionnaire and assessment of three commonly used bowel-cleansing agents

BACKGROUND AND STUDY AIMS

Bowel-cleansing studies are frequently underpowered, poorly designed, and with subjective assessments. Consensus on tolerability of the bowel-cleansing agents is thus lacking. This study developed and validated a bowel-preparation tolerability questionnaire and used it to assess the tolerability of three bowel-cleansing agents, sodium phosphate (NaP), polyethylene glycol (PEG), and sodium picosulphate (Pico), in a prospective randomized single-blinded trial of ambulatory patients.

PATIENTS AND METHODS

The bowel-preparation tolerability questionnaire was validated in 125 consecutive patients and then bowel-preparation agent tolerability was assessed in 634 patients in a prospective randomized single-blinded trial.

RESULTS

The questionnaire's internal consistency was satisfactory with good to excellent "test-retest" reliability for aggregate tolerability and visual analogue scores. Validity assessment confirmed it as reliable and accurate. Of 634 patients, 97.8 % took >75 % of the allocated preparation and 98.9 % completed the questionnaire. Overall, Pico was better tolerated than PEG (p < 0.001) and NaP (p < 0.001). NaP was better tolerated than PEG (p < 0.001). Regardless of the bowel-preparation agent used, males tolerated them better than females (p = 0.009) as did patients having their procedure in the AM. Older patients, however, tolerated all preparations better than younger patients (p = 0.006).

CONCLUSIONS

This study used the first validated bowel-preparation tolerability questionnaire and identified that age, sex, and procedure time all impacted tolerability. Overall, Pico was best tolerated, but PEG's tolerability in patients ≥60 years was equal to that of Pico and NaP, suggesting that PEG can be recommended for older patients to avoid the electrolyte disturbances associated with the osmotic preparations.

Factors associated with dog rabies vaccination in Bhol, Philippines: results of a cross-sectional cluster survey conducted following the island-wide rabies elimination campaign

The Philippines has a long history of rabies control efforts in their dog populations; however, long-term success of such programmes and the goal of rabies elimination have not yet been realized. The Bohol Rabies Prevention and Elimination Program was developed as an innovative approach to canine rabies control in 2007. The objective of this study was to assess canine rabies vaccination coverage in the owned-dog population in Bohol and to describe factors associated with rabies vaccination 2 years after implementation of the programme. We utilized a cross-sectional cluster survey based on the World Health Organization's Expanded Programme on Immunization coverage survey technique. We sampled 460 households and collected data on 539 dogs residing within these households. Seventy-seven per cent of surveyed households reported owning at least one dog. The human-to-dog ratio was approximately 4 : 1, and the mean number of dogs owned per household was 1.6. Based on this ratio, we calculated an owned-dog population of almost 300 000. Overall, 71% of dogs were reported as having been vaccinated for rabies at some time in their lives; however, only 64% of dogs were reported as having been recently vaccinated. Dogs in our study were young (median age = 24 months). The odds of vaccination increased with increasing age. Dogs aged 12-23 months had 4.6 times the odds of vaccination compared to dogs aged 3-11 months (95% CI 1.8-12.0; P = 0.002). Confinement of the dog both day and night was also associated with increased odds of vaccination (OR = 2.1; 95% CI 0.9-4.9; P = 0.07), and this result approached statistical significance. While the programme is on track to meet its goal of 80% vaccination coverage, educational efforts should focus on the need to confine dogs and vaccinate young dogs.

PD05-07: Prospective Validation and Characterization of HER2 Positive Circulating Tumor Cells in Patients with HER2 Negative Metastatic Breast Cancer

Background: Circulating tumor cells (CTCs) with evidence of HER2 amplification can occur in patients (pts) with clinically HER2 negative metastatic breast cancer. While these findings potentially have profound implications for CTCs as a biomarker for treatment, prospective validation and characterization of this subgroup is necessary.

Methods: We created a prospective cohort of pts with metastatic breast cancer that were HER2 negative by IHC and/or FISH on all available primary and metastatic biopsies. Blood samples were collected at study entry and then again at ≥ 3 weeks if available. CTCs were enumerated by a modification of the Veridex CellSearch Profile kit. FISH was performed on each CTC sample and reported as positive if the HER2/CEP17 ratio was ≥ 2.0. Analyses are descriptive.

Results: 66 pts were consented for study and this report includes the 65 pts with detectable CTCs. Median number of CTCs was 226 (range 112 to &gt; 3000). At initial testing, 23 pts (35%) had HER2 positive CTCs, median HER2:CEP17 ratio of 3.4. 50% (11 of 22) of the pts with lobular or ductal/lobular histology had HER2 amplified CTCs, compared to only 27% (10 of 36) of patients with ductal histology. Women with ER positive disease had HER2 positive CTCs in 40% of cases (20 of 49) compared to 19% of ER negative pts (3 of 16). To assess concordance of HER2 amplification of CTCs over time, 34 pts consented to be retested at a median 5.9 weeks after initial screening (range 3.3 - 17 weeks) and all but 1 had detectable CTCs. Baseline characteristics of these 34 pts were similar to the original population, with HER2 amplified CTCs detected in 35% (12 of 34) pts at initial screening. HER2 positive CTCs were concordant at time of retesting in 83% (10 of 12) pts; the 2 women with discordant CTCs were receiving HER2 directed therapy. Of the pts with HER2 negative CTCs at initial screening, 81% (17 of 21) continued to have HER2 negative CTCs at time of retesting.

Conclusion: We observed a higher prevalence of HER2 positive CTCs among pts with ER positive disease and evidence of lobular histology. The presence of HER2 positive CTCs is concordant over time in the majority of pts. The functional significance of HER2 positive CTCs in patients with clinically HER2 negative breast cancer will be tested in a prospective study with HER2−directed therapy.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD05-07.

Integrative mRNA profiling comparing cultured primary cells with clinical samples reveals PLK1 and C20orf20 as therapeutic targets in cutaneous squamous cell carcinoma

Identifying therapeutic targets for cancer treatment relies on consistent changes within particular types or sub-types of malignancy. The ability to define either consistent changes or sub-types of malignancy is often masked by tumor heterogeneity. To elucidate therapeutic targets in cutaneous squamous cell carcinoma (cSCC), the most frequent skin neoplasm with malignant potential, we have developed an integrated approach to gene expression profiling beginning with primary keratinocytes in culture. Candidate drivers of cSCC development were derived by first defining a set of in vitro cancer genes and then comparing their expression in a range of clinical data sets containing normal skin, cSCC and the benign hyper-proliferative condition psoriasis. A small interfering RNA (siRNA) screen of the resulting 21 upregulated genes has yielded targets capable of reducing xenograft tumor volume in vivo. Small-molecule inhibitors for one target, Polo-like kinase-1 (PLK1), are already in clinical trials for other malignancies, and our data show efficacy in cSCC. Another target, C20orf20, is identified as being overexpressed in cSCC, and siRNA-mediated knockdown induces apoptosis in vitro and reduces tumor growth in vivo. Thus, our approach has shown established and uncharacterized drivers of tumorigenesis with potent efficacy as therapeutic targets for the treatment of cSCC.