P6170Incremental value of on-site computed tomography-derived fractional flow reserve for the diagnosis and management strategy of obstructive coronary artery disease in the randomized CRESCENT trials

Background

Coronary computed tomography angiography (CCTA) accurately rules out coronary artery disease (CAD), but has a limited ability to predict hemodynamically significant CAD. Implementing on-site computed tomography-derived fractional flow reserve (CT-FFR) could improve the clinical value and efficiency of cardiac CT in the diagnostic work-up of patients with stable angina.

Purpose

To determine the impact of on-site CT-FFR on diagnostic effectiveness, management strategy and downstream invasive coronary angiography (ICA) in patients with suspected CAD.

Methods

196 patients (59.1±9.6 years, 47% women) with suspected CAD underwent a CCTA in the CRESCENT I and II trials. On-site CT-FFR analysis was performed in all patients with at least one ≥50% stenosis on CCTA (N=53). We assessed the effect of adding CT-FFR analysis to CCTA in terms of 1) diagnostic effectiveness, i.e. the number of additional tests required to determine the final diagnosis; 2) reclassification of the initial management strategy; 3) ICA efficiency, i.e. ICA rate without ≥50% CAD.

Results

CT-FFR was calculated in 42/53 (79%) of the eligible patients as it could not be calculated in patients with suspected coronary total occlusion (N=7), severe coronary calcification (N=2), severe CT artefacts (N=1) or missing CT images (N=1). CT-FFR ≤0.80 was present in 27/196 (14%) patients, including 8/196 (4%) patients with high-risk ischemia (CT-FFR ≤0.80 in all three vessels, left main or proximal left anterior descending coronary artery). The final diagnosis was achieved with CT-FFR in an additional 30/196 (15%) patients compared to CT alone (p<0.0001), and rendered 42/56 (75%) of additional tests unnecessary (p<0.0001). The initial management strategy was reclassified in 30/196 patients (15%, p<0.0001); 24/196 (12%) patients were reclassified to optimal medical therapy and 6/196 (3%) patients were reclassified directly to ICA including 4/8 (50%) patients with high-risk CAD on ICA. CT-FFR would result in 6/32 (19%, p=0.012) ICA cancellations in which none of the patients had high-risk CAD. The rate of ICA without ≥50% stenosis would decrease from 22% (7/32) to 11% (3/27) (p=0.012).

Conclusion

Implementation of CT-FFR has the potential for improved diagnostic effectiveness. Functional reclassification of CAD provides more efficient ICA referral in patients with suspected CAD compared to CTA alone.

Acknowledgement/Funding

Dutch Heart Foundation [NHS 2014T061 and NHS 2013T071]

Genome-wide association studies identify four ER negative-specific breast cancer risk loci

Estrogen receptor (ER)-negative tumors represent 20-30% of all breast cancers, with a higher proportion occurring in younger women and women of African ancestry. The etiology and clinical behavior of ER-negative tumors are different from those of tumors expressing ER (ER positive), including differences in genetic predisposition. To identify susceptibility loci specific to ER-negative disease, we combined in a meta-analysis 3 genome-wide association studies of 4,193 ER-negative breast cancer cases and 35,194 controls with a series of 40 follow-up studies (6,514 cases and 41,455 controls), genotyped using a custom Illumina array, iCOGS, developed by the Collaborative Oncological Gene-environment Study (COGS). SNPs at four loci, 1q32.1 (MDM4, P = 2.1 × 10(-12) and LGR6, P = 1.4 × 10(-8)), 2p24.1 (P = 4.6 × 10(-8)) and 16q12.2 (FTO, P = 4.0 × 10(-8)), were associated with ER-negative but not ER-positive breast cancer (P > 0.05). These findings provide further evidence for distinct etiological pathways associated with invasive ER-positive and ER-negative breast cancers.

Leukotriene B4, 8-iso-prostaglandin F2 alpha, and pH in exhaled breath condensate from asymptomatic smokers

Long-term cigarette smoking is the major etiological factor for the development of chronic obstructive pulmonary disease (COPD). Airway inflammation and oxidative stress are implicated in the pathogenesis. Biomarkers reflecting these responses could be analyzed in exhaled breath condensate (EBC). Recently, it became obvious that mediator concentrations in EBC could be influenced by age of the subjects, equipment, sampling properties, and the analytical assays applied. In the present study we evaluated 8 smokers (20-56 yr) and 16 non-smoking adults (18-60 yr) with normal spirometry and no episode of airway infection during 6 weeks prior to the study. EBC samples were obtained with the commercial device ECoScreen2 at a controlled temperature of -20 degrees C. Leukotriene B(4) (LTB(4), marker of inflammation), 8-iso-prostaglandin F(2 alpha) (8-iso-PGF(2 alpha)/8-isoprostane, oxidative stress) concentrations, and pH were measured. With 10 min of tidal breathing, a lower EBC volume was collected in smokers (median 1.22 ml; interquantil range 1.06-1.74 ml) than in non-smokers (1.6 ml; 1.16-2.21 ml; P=0.06). Significant differences were found in pH in smokers compared with non-smokers (7.14 (5.70-7.43) vs. 7.59 (7.28-7.73); P<0.01). No significant differences were observed in EBC concentrations of LTB(4) or 8-iso-PGF(2 alpha). The study demonstrates that acidopnea is detectable in otherwise asymptomatic smokers and might precede changes in the level of arachidonic acid metabolites. For pH is considered to be the most validated marker determined in EBC samples, it may be useful for screening asymptomatic individuals for smoking-induced early airway damage.

Association between genetic polymorphisms in styrene-metabolizing enzymes and biomarkers in styrene-exposed workers

Single-nucleotide polymorphisms (SNP) in genes of styrene-metabolizing enzymes could modulate biomarker concentrations in blood or urine after exposure to styrene. Ten SNP were analyzed to study their influence on styrene-specific biomarkers in 89 workers of a fiber-reinforced plastic boat building factory. The internal styrene body burden was analyzed in post-shift blood and urine samples. External styrene exposure was measured by passive samplers. Spearman rank correlations between styrene exposure and biomarkers were calculated and distributions of biomarkers were checked for lognormality. Mixed linear models were applied to analyze the influence of genotypes and styrene exposure, on styrene in blood (Monday and Thursday post-shift) and on phenyglyoxylic acid (PGA; adjusted for day of measurement, Monday to Thursday) due to a lognormal distribution, smoking (current, not current), and use of respirators. Stratified analyzes for workers without and with different types of respirators were also performed. The models of both the subgroups revealed a significant influence dependent on the respirator type that workers used for inhalation protection. An influence of the external styrene concentration on the urinary PGA concentration was not observed. After implementation of the SNP into the model significant lower adjusted means of urinary PGA concentrations were found for GSTP1 105IleVal and CYP2E1 -71TT. For styrene levels in blood no significant effect was observed. A significant influence on styrene levels in blood was correlated with external styrene concentration only in workers without use of respirators. The effects of two SNP on urinary PGA decrease indicated a limited modulating SNP effect. The most effective prevention for styrene exposure was obtained with the wearing of respirators.

A study on lung cancer mortality related to radon, quartz, and arsenic exposures in German uranium miners

Between 1946 and 1990 uranium mining was undertaken on a large scale in East Germany. This study evaluates the proportional lung cancer risk of German uranium miners from radon, quartz, and arsenic exposure during mining operations at the WISMUT Corporation. The database of the WISMUT tissue repository and a comprehensive job-exposure matrix were used to compare exposure levels of lung cancer cases with deaths from diseases of the circulatory system for risk analysis. In addition, the ratio of lung cancer cases was compared to cases from diseases of the circulatory system to the corresponding ratio in the general population. The proportional lung cancer mortality of German uranium miners was 2.9-fold higher than in the general population of East Germany. Cumulative radon, quartz, and arsenic exposure were determined as risk factors for lung cancer among German uranium miners, where silicosis modified the risk of cumulative radon and quartz exposure. Silicotics were exposed to higher levels of quartz, radon, and arsenic than nonsilicotics. Because selection of the study population was based on a tissue repository, the results need to be interpreted with caution.

Head and neck squamous-cell cancer and its association with polymorphic enzymes of xenobiotic metabolism and repair

Tobacco smoking, alcohol drinking, and occupational exposures to polycyclic aromatic hydrocarbons are the major proven risk factors for human head and neck squamous-cell cancer (HNSCC). Major research focus on gene-environment interactions concerning HNSCC has been on genes encoding enzymes of metabolism for tobacco smoke constituents and repair enzymes. To investigate the role of genetically determined individual predispositions in enzymes of xenobiotic metabolism and in repair enzymes under the exogenous risk factor tobacco smoke in the carcinogenesis of HNSCC, we conducted a case-control study on 312 cases and 300 noncancer controls. We focused on the impact of 22 sequence variations in CYP1A1, CYP1B1, CYP2E1, ERCC2/XPD, GSTM1, GSTP1, GSTT1, NAT2, NQO1, and XRCC1. To assess relevant main and interactive effects of polymorphic genes on the susceptibility to HNSCC we used statistical models such as logic regression and a Bayesian version of logic regression. In subgroup analysis of nonsmokers, main effects in ERCC2 (Lys751Gln) C/C genotype and combined ERCC2 (Arg156Arg) C/A and A/A genotypes were predominant. When stratifying for smokers, the data revealed main effects on combined CYP1B1 (Leu432Val) C/G and G/G genotypes, followed by CYP1B1 (Leu432Val) G/G genotype and CYP2E1 (-70G>T) G/T genotype. When fitting logistic regression models including relevant main effects and interactions in smokers, we found relevant associations of CYP1B1 (Leu432Val) C/G genotype and CYP2E1 (-70G>T) G/T genotype (OR, 10.84; 95% CI, 1.64-71.53) as well as CYP1B1 (Leu432Val) G/G genotype and GSTM1 null/null genotype (OR, 11.79; 95% CI, 2.18-63.77) with HNSCC. The findings underline the relevance of genotypes of polymorphic CYP1B1 combined with exposures to tobacco smoke.

Rapid detection of the hOGG1 Ser326Cys polymorphism using LightCycler technology

Human 8-oxoguanine DNA glycosylase 1 (hOGG1) plays an important role in the repair of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodGuo), one of the major constituents in DNA damage. A recent in vitro study showed that the hOGG1 326Cys polymorphism (rs1052133) exhibits reduced 8-oxodGuo repair activity. This study aimed to develop a LightCycler (LC) assay to analyze the C>G polymorphism (Ser326Cys) in exon 7 of the hOGG1 gene followed by validation of the method using DNA samples from 260 polycyclic aromatic hydrocarbons(PAH)-exposed workers with known 8-oxodGuo DNA-adduct values measured by HPLC. Twenty DNA samples were analyzed by a PCR-RFLP analysis with Fnu4H I to generate control DNA. LC melting curve analyses of the hOGG1 exon 7 PCR product were characteristic of the probes hybridized to the non-mutated Ser-type (CC) at 65 degrees C, or to the Cys mutant (GG) at 59 degrees C. The distribution in the population of PAH-exposed workers (N=260) was 58% (CC), 38%(CG), and 4% (GG). The minor G allele displayed a frequency of 23 %. The distribution of 8-oxodGuo adducts for the Ser326Cys variants of hOGG1 revealed geometric means (GM) of 5.83 (CC), 5.27 (CG), and 6.53 (GG) 8-oxodGuo adducts/10(6)dGuo. Corresponding GM values of current smokers were 5.7 (CC), 5.6 (CG) and 7.0 (GG) 8-oxodGuo adducts/10(6) dGuo. The analysis of the Ser326Cys polymorphism in 260 DNA samples with this new LC assay revealed that this method is reliable for high throughput analysis of this key polymorphism in the hOGG1 gene.

Role of exposure to radon and silicosis on the cell type of lung carcinoma in German uranium miners

BACKGROUND

In East Germany, uranium mining was undertaken on a large scale from 1946 to 1990. Poor working conditions led to a high level of exposure to ionizing radiation and quartz dust. This analysis evaluates the histopathology of lung carcinoma in uranium miners in relation to radon exposure and silicosis.

METHODS

A database developed for autopsy cases ascertained in a pathological tissue repository of German uranium miners was used to estimate odds ratios for developing lung carcinoma by major cell type with regard to radon exposure and silicosis. Silicosis information was extracted from autopsy protocols. Working level months (WLM) were calculated with a job-exposure matrix to assess lifetime radon exposure. Risk estimates were based on 3414 male miners who died from small cell lung carcinoma (SCLC, n = 1446), squamous cell carcinoma (SqCC, n = 1006), or adenocarcinoma (AC, n = 962) between 1957 and 1990.

RESULTS

SCLC and SqCC seem more likely to be associated with high radon exposure than AC. Mean cumulative radon exposure was 868 (SD 631) WLM in SCLC, 871 (SD 652) WLM in SqCC, and 743 (SD 598) WLM in AC. Silicosis prevalence was 26% in SCLC, 38% in SqCC, and 30% in AC. In silicotics, AC and SqCC had a relatively higher frequency at the expense of SCLC. SCLC occurred earlier than AC and SqCC.

CONCLUSION

High radon exposure was associated with a higher relative frequency of SCLC and SqCC than AC. Silicosis tended to increase the appearance of SqCC and AC.

A new method to bind allergens for the measurement of specific IgE antibodies

BACKGROUND

Detection of allergen-specific IgE antibodies in patients' sera plays a key role for the diagnosis of IgE-mediated allergy. If no validated test system is available, diagnostic tools must be developed, usually by coupling or binding the allergens to a solid phase. Streptavidin ImmunoCAP is a new solid phase for binding of allergens which can be used in the Pharmacia CAP system.

OBJECTIVE

It was the aim of this study to assess the diagnostic validity of Streptavidin ImmunoCAP.

METHODS

Biotinylation and allergen concentration for binding to Streptavidin ImmunoCAP were optimized and IgE obtained with natural rubber latex, obeche wood, wheat and rye flour Streptavidin ImmunoCAP were compared with the results of ImmunoCAP and Enzyme Allergo-Sorbent Test (EAST) using sera from patients complaining of workplace-related respiratory symptoms.

RESULTS

While the relation of biotin-label and protein was critical (best results were obtained with a 5- fold molar excess), labelled protein for coupling to streptavidin ImmunoCAP was applicable in a wide concentration range. On average, IgE values with streptavidin ImmunoCAP were as high as with ImmunoCAP but considerably higher than values obtained by EAST.

CONCLUSION

Streptavidin ImmunoCAP is a valuable tool for sensitive and specific measurement of IgE binding to new allergens superior to cellulose disk-based methods.

A microcomputer-based, R-wave triggered system for hemodynamic measurements in the forearm

A microcomputer (with 8088 or 80286 processor)-based, R-wave triggered system for on-line, semi-continuous measurement of blood flow of one or two limbs, simultaneous with heart rate and eventually intra-arterial blood pressure, is described. The minimal interval between measurements is approximately 4 s, allowing the accurate measurement of maximal flow after ischemia. When compared to hand-operated plethysmography, the use of this system improves the precision of the measurements, minimizes perturbations of the limb circulation and eliminates the possible bias of analysis by hand.

Wheelchair caster shimmy and turning resistance

The equations for wheelchair caster wheel shimmy are presented along with experimental data. The report includes the theory and performance of single wheel casters for a variety of tires, and a new design for wheelchair casters using a grooved dual-tread tire or co-rotating caster wheels. The dual-tread tire was found to significantly inhibit caster shimmy. The turning resistance due to a grooved caster wheel tire with a 1/2-inch groove was found to be 10 percent greater than for an ungrooved caster wheel tire. The analysis includes the methodology and the results of experiments developed to measure the sliding friction turning moment of the wheelchair caster wheel. A number of commercial wheelchair caster wheels were tested and the results for shimmy are presented.

Wheelchair batteries: driving cycles and testing

The battery performance of electric wheelchairs was measured under indoor and outdoor conditions, and simulated driving cycles for these two environments were derived from these tests. Driving cycles were used to bench-test deep discharge wet cell and gel cell lead-acid batteries, nickel-cadmium batteries, and experimental nickel-zinc batteries. Results of this study support the conclusion that deep discharge wet cell lead-acid batteries satisfy wheelchair requirements and are the most economical choice. The effect of simulated wheelchair controller pulse width modulation on battery discharge compared to d.c. discharge was found to be negligible. A simple model analogous to Miner's Rule (3) plus results plotted on a Ragone chart of average power versus discharge time were found to correlate the effect of the highly variable actual power requirements of an electric wheelchair. Miner's Rule can predict battery performance for a given driving cycle.