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Fischer-Tropsch conversion of natural gas to liquid hydrocarbon fuel typically includes Fischer-Tropsch synthesis followed by refining (hydrocracking and distillation) of the syncrude into mostly diesel or kerosene with some naphtha (a feedstock for gasoline production). Refining is assumed necessary, possibly overlooking the exceptional fuel qualities of syncrude for more direct utilization as a compression-ignition (CI) fuel. This paper evaluates cetane number, viscosity, cloud-point, and pour-point properties of syncrude and blends of syncrude with blend stocks such as ethanol and diethyl ether. The results show that blends comprised primarily of syncrude are potentially good CI fuels, with pour-point temperature depression being the largest development obstacle. The resulting blends may provide a much-needed and affordable alternative CI fuel. Particularly good market opportunities exist with Environmental Policy Act (EPACT) applications.

Background: Greater abdominal adiposity is associated with insulin resistance and obesity-related vascular disease. Physical activity (PA) is inversely associated with abdominal adiposity yet associations between trends in adherence to PA recommendations through young adulthood and abdominal adiposity in middle age is unclear. Objective: To identify common trajectories of maintaining recommended levels of PA through young adulthood and to examine associations between trajectories and abdominal adiposity at middle age. Methods: The Coronary Artery Risk Development in Young Adults (CARDIA) study is a population-based, prospective, observational study of black and white men and women. PA was assessed at 8 exams across 25 years of follow-up. PA trajectories were identified by group-based modeling (PROC TRAJ) based on likelihood of maintaining recommended PA levels across exams. Visceral, subcutaneous, and abdominal intermuscular adipose tissue volumes (cm3) were assessed by computed tomography at the year 25 exam (43-55 yrs, n=3180). Results: Four major PA trajectories were identified: highly active (27.3%), declining activity (18.2%), modestly active (20.7%) and always sedentary (33.8%). Abdominal adipose tissue volumes by PA trajectory, race, and sex are displayed in Figure 1. Among white men and women, abdominal adiposity was lowest in always active adults and highest in those always sedentary; higher abdominal adiposity was observed with declining activity compared to modest activity. In black women, highest levels of abdominal adiposity were observed with declining activity. Black men exhibited no differences in abdominal adiposity across PA trajectory groups. Conclusions: Maintaining recommended physical activity levels through young adulthood is associated with lower abdominal adiposity at middle age. Highly active adults who exhibit declining physical activity towards middle age exhibit higher abdominal adiposity compared to adults with consistent modest activity throughout adulthood.

Background: Coronary artery disease (CAD) starts in childhood and progresses to advanced lesions in adult life. The coronary artery calcium (CAC) score is a measure of subclinical CAD that indicates advanced coronary atheroma and independently predicts future clinical events. Our objective was to document the prevalence and amount of subclinical CAD among black and white adults in early adult life. Methods: The Coronary Artery Risk Development in Young Adults (CARDIA) study is a U.S. population-based, prospective, observational study of black and white men and women. Initially 5,115 participants age of 18-30 yrs were recruited in 1985-6. CAC was measured using non-contrast cardiac CT and reported as the Agatston score at three exams 15, 20 & 25 years after the baseline visit. Results: CAC prevalence was 10.1%(309/3046), 18.6%(583/3140) and 28.1%(890/3160) when the returning cohort was between 33-45 yrs, 38-50 yrs, and 43-55 yrs, respectively (see figure). Prevalence of CAC at all time points was greater in men than women and highest in white men. In the most recent exam, black men had a lower prevalence of CAC (34.3% vs 47.7%) compared to white men but similar distribution of CAC amount. Quartiles of CAC among men with any CAC were: black men 10, 48, 183 and white men 14, 42, 173 (Q1, Q2(median) and Q3 respectively). Change in CAC score among participants in the two most recent CT exams was observed in 29.8% (774/2600). Of those participants, 89.3%(691/774) had any increase in CAC score and 66.7%(516/774) an increase of 10 units or greater. Prevalence of CAC was highly correlated with age and no period effect was observed. Conclusions: 28% of adults less than 55 years of age have advanced plaque in their coronary arteries indicating significant subclinical disease burden. Prevalence is highest in white men, followed by black men and then women in these age ranges. Black men, given CAC, have a comparable amount of CAC to white men. Subclinical CAD is prevalent in early adulthood and once initiated appears to progress in the vast majority of adults.

Background: Abdominal aorto-iliac atherosclerosis occurs earlier in the course of disease than coronary artery atherosclerosis and is often present in persons free of coronary atherosclerosis. Accounting for this early stage of disease might improve the ability to evaluate risk factors for atherosclerosis. Objective: We examined the associations of major risk factors with the presence of coronary artery calcium (CAC) and abdominal aorto-iliac calcium (AoIC) in the absence of CAC in 1994 black and white men and women participating in the CARDIA study at the year 25 exam in 2010–11. Methods: Multinomial logistic regression was used to examine the associations of risk factors measured at year 15 with the presence of CAC and AoIC (Agatston scores ≥1) at year 25. Ordinary logistic regression was used to examine the associations of risk factors with presence of CAC (ignoring AoIC) at year 25. Results: 457 (22.9%) had both CAC and AoIC, 139 (7.0%) had CAC only, 632 (31.7%) had AoIC only, and 766 (38.4%) had neither. The 596 with CAC (+/−AoIC) were analyzed as one group vs. AoIC only, both in comparison with no calcification. Most risk factors had similar association with CAC (+/−AoIC) and AoIC only, including total and HDL cholesterol, triglycerides, systolic and diastolic blood pressure, smoking status, waist circumference and education. When comparing odds ratios (OR) for CAC (+/−AoIC) and AoIC only, both vs. no calcification, substantial differences were seen for comparisons of blacks vs whites (0.52 for CAC, p Conclusions: AoIC, an early manifestation of subclinical atherosclerosis, is associated with the major risk factors for CAC. The race and sex differences shown here, including little race or sex difference in AoIC only, are consistent with previous autopsy studies and deserve further etiologic research. Accounting for the presence of AoIC without CAC results in stronger estimates of risk factor associations with CAC. Studies that have not accounted for the presence of atherosclerosis in other vascular beds may have under-estimated the associations of established and novel risk factors with CAC.

Previous research suggests that visceral adipose tissue (VAT) increases risk for atherosclerosis and specifically arterial calcification, yet the association of subcutaneous adipose tissue (SAT) with calcification is less substantiated. Studies have also noted important race and sex differences in risk of atherosclerosis. In the Family Heart Study, we examined race and sex differences in the pattern of associations of abdominal fat depots with coronary (CAC) and abdominal aorto-iliac (AAC) calcified plaque measured using computed tomography (CT). Methods- We used CT to measure abdominal fat volume and arterial calcified plaque in 2,748 participants of European American descent (EA; n=1512 females) and 626 participants of African American descent (AA; n=412 females) in the Family Heart Study. CAC and AAC were defined as present (≥1) or absent (0) based on Agatston scores. Odds ratios (OR) and 95% confidence intervals (95% CI) were determined using logistic regression models adjusted for age, field center, family pedigree, race, and history of coronary heart disease (CHD), diabetes, hypertension, hypercholesterolemia, and smoking. Results- The association of SAT and VAT with prevalent CAC and AAC varied with sex and race in multivariable logistic regression models. In males, SAT was strongly associated with both CAC (p=0.001) and AAC (pinteraction SAT*race p Conclusions- Abdominal SAT was associated with both CAC and AAC prevalence in males, and associations appeared to be stronger in EA compared to AA participants. VAT was predictive of CAC in both EA and AA males. In contrast, SAT and VAT were only associated with CAC in females and no differences by race were noted. Our findings suggest that SAT, and by inference obesity, along with VAT may be an important contributors to prevalence of arterial calcification and that race plays a role in associations among males.

Background: Prior studies suggest that African Americans (AA) have lower prevalence of coronary artery calcium (CAC) compared to whites, yet CAC has similar ability to predict coronary heart disease (CHD) events. The role of CAC as a screening tool for CHD risk in AA is unclear. We compared the diagnostic accuracy for CHD prevalence using the CAC score and the Framingham Risk Score (FRS) in an adult population of AA. Methods: CAC was measured in 2944 participants in the Jackson Heart Study, an NHLBI funded study of AA based in Jackson, MS. Approximately 8% of this cohort had known cardiovascular disease (CVD) defined as prior MI, angina, stroke, PTCA, CABG or PVD. Logistic regression, ROC and net reclassification index (NRI) analysis were used adjusting for age, gender, SBP, total and HDL cholesterol, smoking status, DM and BMI. FRS was calculated and those with DM were classified as high risk. Results: The mean age was 60, 65% were females, 26% had DM, 50% were obese and 30% were current or former smokers. Prevalent CVD was associated with older age, higher SBP, lower HDL and total cholesterol, and higher CAC. CAC was independently associated with prevalent CVD in our multivariable model [OR (95% CI): 1.26 (1.17, 1.35), p< 0.0001]. In ROC analysis, CAC improved the diagnostic accuracy (c statistic) of the FRS from 0.617 to 0.757 (p < 0.0001) for prevalent CVD. The FRS classified 30% of the cohort as high risk, 38.5% as intermediate risk and 31.5% as low risk. FRS classfied 51% of subjects with prevalent CVD as high risk. Addition of CAC to FRS resulted in net reclassification improvement of 4% for subjects with known CVD and 28.5% in those without CVD (see figure). Conclusion: In AA, the CAC is independently associated with prevalent CVD and improves the diagnostic accuracy of FRS for prevalent CVD by 14%. Addition of CAC improves the NRI of those with prevalent CVD by 4% and the NRI of individuals without CVD by 28.5%. Determination of CAC in AA may be useful in identifying individuals at risk of CVD and reclassifying individuals with low and intermediate FRS.

For over a decade investigators have quantified cholesterol absorption by comparison of dietary intake and fecal excretion of isotopic cholesterol with that of beta-sitosterol as a "nonabsorbable" marker. However, beta-sitosterol might not be ideal due to its potential for absorption. We therefore carried out two studies to evaluate a new marker with less potential for absorption, [3H]beta-sitostanol. In the first study (Study I, n = 22), we compared absorption of [3H]beta-sitostanol and [14C]beta-sitosterol in a simultaneous dual-label continuous feeding ("phytosterol absorption") experiment. We observed a consistently higher ratio of [3H]beta-sitostanol/[14C]beta-sitosterol in the stool relative to diet on the first day of fecal collection (6.1% +/- 3.2% loss of [3H]beta-sitosterol, range 3-12%), but thereafter, the ratio in stool was similar to that in diet. In Study II (n = 23), we compared cholesterol absorption directly using [3H]beta-sitosterol and [14C]cholesterol, and, separately, [3H]beta-sitostanol and [14C]cholesterol. We found that mean absorption between the two methods was similar (45% +/- 11% versus 44% +/- 10%, respectively, P difference = 0.40), and the two methods correlated well with one another (r = 0.83) when samples from all available days were used. Variability between the two methods was greater in individuals who absorbed more than 40% of cholesterol. Cholesterol loss on day 2 estimated from use of beta-sitostanol as a nonabsorbable marker was predictive of absorption using ratios from days 4-6 (r = 0.80). These results suggest that, for the majority of subjects, beta-sitosterol is a valid nonabsorbable marker for cholesterol absorption.

Four children treated for acute lymphoblastic leukemia developed intracranial gliomas between 40 and 120 months following multiagent chemotherapy, prophylactic whole brain irradiation, and intrathecal Methotrexate. The diagnosis of glioma was confirmed in each case with biopsy or autopsy. These children were part of a larger series of 73 patients with acute lymphoblastic leukemia treated at Indiana University receiving 24 Gy as per the protocol guidelines of the Children's Cancer Study Group. Currently 42 patients of the original 73 children survive in continuous remission.