Road centre line simplification principles for angular segment analysis

Angular segment analysis is one of the most fundamental analyses in space syntax practice that helps understand movement, land-use and other socio-economic patterns. It was initially applied in axial segment maps and later was used in road centre line maps as an attempt to overcome the 'segment problem' (Turner, 2005). Furthermore, the growing need to examine large urban systems has led to the wide use of road centre line maps instead of the previously hand-drawn axial maps. However, this transition to such datasets has lacked systematic studies on what is required to convert a road centre line map into a segment map, in order to produce reliable results of the angular segment analysis. To date, no consensual methodology has been developed within the space syntax community. This paper attempts to clarify what a road centre line segment represents spatially and suggests principles and rules to simplify a road centre line map to a segment map. Based on previous experience, the simplification mostly relies on the following two principles: reducing the number of nodes in the dual graph representation of a street network; optimising the angular change between adjacent nodes of the dual graph when space allows it. In addition to the above general principles, we discuss rules for special and complex cases, e.g. roundabouts, underpasses, bridges etc. To evaluate these rules and principles comparisons are carried out between traditional axial and RCL unsimplified and simplified segment maps, to develop a good understanding of how changes in dual graph representation of a street network can affect space syntax measure of 'choice'. Correlations of angular segment choice values are performed in order to evaluate which simplification technique can approximate better the axial representation of actual human activity. The results show that using a raw road centre line data set raises several inconsistencies in the analysis results, and the progressive application of the different simplification techniques brings these results closer to those of a traditional axial segment map, and thus to a better representation of socio-economic activity. The purpose of simplification is to minimise inconsistencies to ensure maximum accuracy in the results of angular segment analysis

Low fasting low high-density lipoprotein and postprandial lipemia

BACKGROUND: Low levels of high density lipoprotein (HDL) cholesterol and disturbed postprandial lipemia are associated with coronary heart disease. In the present study, we evaluated the variation of triglyceride (TG) postprandially in respect to serum HDL cholesterol levels. RESULTS: Fifty two Greek men were divided into 2 main groups: a) the low HDL group (HDL < 40 mg/dl), and b) the control group. Both groups were further matched according to fasting TG (matched-low HDL, and matched-control groups). The fasting TG concentrations were higher in the low HDL group compared to controls (p = 0.002). The low HDL group had significantly higher TG at 4, 6 and 8 h postprandially compared to the controls (p = 0.006, p = 0.002, and p < 0.001, respectively). The matched-low HDL group revealed higher TG only at 8 h postprandially (p = 0.017) compared to the matched-control group. ROC analysis showed that fasting TG ≥ 121 mg/dl have 100% sensitivity and 81% specificity for an abnormal TG response (auc = 0.962, p < 0.001). CONCLUSIONS: The delayed TG clearance postprandially seems to result in low HDL cholesterol even in subjects with low fasting TG. The fasting TG > 121 mg/dl are predictable for abnormal response to fatty meal

Sex-associated effect of CETP and LPL polymorphisms on postprandial lipids in familial hypercholesterolaemia

Background: This study assessed the gender-specific influence of the cholesteryl ester transfer protein (TaqIB, I405V) and lipoprotein lipase (S447X) polymorphisms on the response to an oral fat tolerance test in heterozygotes for familial hypercholesterolaemia.Methods: We selected and genotyped 80 men and postmenopausal women heterozygous for familial hypercholesterolaemia (main group) as well as 11 healthy control subjects. Patients were subgrouped based on their response to oral fat tolerance test. The oral fat tolerance test was defined as pathological when postprandial triglyceride concentration was higher than the highest triglyceride concentration observed in healthy subjects (220 mg/dl) at any time (2, 4, 6 or 8 h).Results: In the pathological subgroup, men had significantly higher incremental area under the curve after oral fat tolerance test than postmenopausal women. Furthermore, multivariate analysis revealed a gender association of TaqIB and I405V influence on postprandial lipaemia in this subgroup.Conclusion: In conclusion, it seems that gender and TaqIB polymorphism of the cholesteryl ester transfer protein gene were both associated with the distribution of triglyceride values after oral fat tolerance test, only in subjects with a pathological response to oral fat tolerance test. Specifically, men carrying the B2 allele of the TaqIB polymorphism showed a higher postprandial triglyceride peak and a delayed return to basal values compared with women carrying B2. However, further investigations in larger populations are required to replicate and confirm these findings

Postprandial lipemia in men with metabolic syndrome, hypertensives and healthy subjects

BACKGROUND: The metabolic syndrome (MetS), as well as postprandial hypertriglyceridemia, is associated with coronary heart disease. This study aimed to evaluate the postprandial lipemia after oral fat tolerance test (OFTT) in subjects with MetS and compare them to hypertensive (HTN) and healthy subjects. RESULTS: OFTT was given to 33 men with MetS (defined by the Adult Treatment Panel III), 17 HTN and 14 healthy men. The MetS group was further divided according to fasting triglycerides (TG) into TG ≥ 150 [MetS+TG, (n = 22)] or <150 mg/dl [MetS-TG (n = 11)], and into those with or without hypertension [MetS+HTN (n = 24), MetS-HTN (n = 9), respectively]. TG concentrations were measured before and at 4, 6 and 8 h after OFTT and the postprandial response was quantified using the area under the curve (AUC) for TG. The postprandial response was significantly higher in MetS compared to HTN and healthy men [AUC (SD) in mg/dl/h; 2534 ± 1016 vs. 1620 ± 494 and 1019 ± 280, respectively, p ≤ 0.001]. The TG levels were increased significantly in MetS+TG compared to MetS-TG subjects at 4 (p = 0.022), 6 (p < 0.001) and 8 hours (p < 0.001). The TG were increased significantly in MetS-TG compared to healthy subjects at 4 (p = 0.011), 6 (p = 0.001) and 8 hours (p = 0.015). In linear regression analysis only fasting TG levels were a significant predictor of the AUC (Coefficient B = 8.462, p < 0.001). CONCLUSION: Fasting TG concentration is the main determinant of postprandial lipemia. However, an exaggeration of TG postprandialy was found in normotriglyceridemic MetS and HTN compared to healthy subjects. This suggests that intervention to lower fasting TG levels should be recommended in MetS subjects

The effect of dietary fish oil on weight gain and insulin sensitivity is dependent on APOE genotype in humanized targeted replacement mice

We investigated the independent and interactive impact of the common APOE genotype and marine n-3 polyunsaturated fatty acids (PUFA) on the development of obesity and associated cardiometabolic dysfunction in a murine model. Human APOE3 and APOE4 targeted replacement mice were fed either a high-fat control diet (HFD) or a HFD supplemented with 3% n-3 PUFA from fish oil (HFD + FO) for 8 wk. We established the impact of intervention on food intake, bodyweight, and visceral adipose tissue (VAT) mass; plasma, lipids (cholesterol and triglycerides), liver enzymes, and adipokines; glucose and insulin during an intraperitoneal glucose tolerance test; and Glut4 and ApoE expression in VAT. HFD feeding induced more weight gain and higher plasma lipids in APOE3 compared to APOE4 mice (P < 0.05), along with a 2-fold higher insulin and impaired glucose tolerance. Supplementing APOE3, but not APOE4, animals with dietary n-3 PUFA decreased bodyweight gain, plasma lipids, and insulin (P < 0.05) and improved glucose tolerance, which was associated with increased VAT Glut4 mRNA levels (P < 0.05). Our findings demonstrate that an APOE3 genotype predisposes mice to develop obesity and its metabolic complications, which was attenuated by n-3 PUFA supplementation.—Slim, K. E., Vauzour, D., Tejera, N., Voshol, P. J., Cassidy, A., Minihane, A. M. The effect of dietary fish oil on weight gain and insulin sensitivity is dependent on APOE genotype in humanized targeted replacement mice

Recruitment and retention of participants from socioeconomically deprived communities : lessons from the Awareness and Beliefs About Cancer (ABACus3) randomised controlled trial

Background Recruitment of research participants poses challenges in socioeconomically deprived areas. The Awareness and Beliefs About Cancer (ABACus) phase 3 Randomised Control Trial recruited adult participants from socioeconomically deprived areas using a combined healthcare/community engagement model. We report the strategies used to successfully recruit and retain our trial participant sample. Methods Community and healthcare settings in areas of high socioeconomic deprivation were identified by lay advisors who recruited participants opportunistically or by appointment. Follow-up was done by telephone or post at 2-weeks and 6-months after recruitment, and all participants were offered financial incentives. Qualitative interviews were conducted with lay advisors regarding their experience and reflections. Results The lay advisors identified and contacted 107 potential recruitment venues across South and West Yorkshire and South East Wales of which 41.1% (n = 42) were opened for recruitment. A total of 234 participants were recruited, with 91% (n = 212) retention at 2-weeks and 85% (n = 199) at 6-months. Community settings yielded 75% (n = 176) of participants. Participants had a mean age of 61.3 years and 63.3% (n = 148) were female, with 66% (n = 154) resident in the most deprived geographical areas. Lay advisors described recruitment as intensive, although engaging participants was easier in community settings. Conclusions The ABACus3 trial achieved recruitment and high retention with a population that is often “hard to reach” or entirely missed in health research. Strategies were specifically tailored to engage the venues and adult residents of highly deprived areas. Future studies recruiting adults living in the most deprived areas might benefit from community recruitment and from collaborating with local gatekeepers who are key to engagement. This study adheres to CONSORT guidelines. Trial registration Retrospectively registered with ISRCTN (http://www.isrctn.com/ISRCTN16872545) on 12.01.2018