Replacement of dietary saturated fatty acids by trans fatty acids lowers serum HDL cholesterol and impairs endothelial function in healthy men and women

We tested whether trans fatty acids and saturated fatty acids had different effects on flow-mediated vasodilation (FMD), a risk marker of coronary heart disease (CHD). Consumption of trans fatty acids is related to increased risk of CHD, probably through effects on lipoproteins. Trans fatty acids differ from most saturated fatty acids because they decrease serum high-density lipoprotein (HDL) cholesterol, and this may increase the risk of CHD. We fed 29 volunteers 2 controlled diets in a 2x4-week randomized crossover design. The "Trans-diet" contained 9.2 energy percent of trans fatty acids; these were replaced by saturated fatty acids in the "Sat-diet." Mean serum HDL cholesterol after the Trans-diet was 0.39 mmol/L (14.8 mg/dL), or 21␕ower than after the Sat-diet (95␌I 0.28 to 0.50 mmol/L). Serum low density lipoprotein and triglyceride concentrations were stable. FMD SD was 4.4±2.3fter the Trans-diet and 6.2±3.0fter the Sat-diet (difference -1.8°95␌I -3.2 to -0.4). Replacement of dietary saturated fatty acids by trans fatty acids impaired FMD of the brachial artery, which suggests increased risk of CHD. Further studies are needed to test whether the decrease in serum HDL cholesterol caused the impairment of FMD

Experimental investigation of calcium carbonate mineralogy in past and future oceans

Inorganic marine calcium carbonate formation and mineralogy varies significantly concurrent with the solution composition. During the Phanerozoic, due to oscillations in the seawater composition, this resulted in the formation of either dominantly calcite or aragonite. Variations in seawater composition also appear to have influenced the evolution of biomineralizing organisms. Additionally, many organisms utilize amorphous calcium carbonate (ACC) during biomineralization. The occurrence of calcite and aragonite throughout the Phanerozoic and calcium carbonate biomineralization were investigated. This was done by determining the influence of solution chemistry (SO4 and Mg) on calcium carbonate formation, mineralogy and stability via a variety of laboratory and synchrotron based synthesis experiments. During the formation of aragonite and calcite, aqueous SO4 and the Mg/Ca ratio both affect the formation of calcite and aragonite. An increase in aqueous SO4 decreases the Mg/Ca ratio at which calcite is destabilized and aragonite becomes dominant. These results suggest that the models relating seawater chemistry to calcium carbonate formation needs re-evaluation. Abiotic ACC crystallization to vaterite occurs in three stages. In the first stage, ACC crystallizes to vaterite via a spherulitic growth mechanism. The second stage is characterized by surface particle growth at the expense of ACC. Finally, particle growth via Ostwald ripening is the only remaining process. This process can be described as the inorganic analogue to biological ACC crystallization, which is adjusted by organisms to produce their preferred calcium carbonate polymorph and morphology. An increase in SO4 concentration only decreases the spherulitic growth rate and Ostwald ripening, even when rapidcreekite (as an intermediate) and gypsum crystallizes. Finally, SO4 promotes the formation of vaterite. Depending on the formation process this is caused by either the stabilization of vaterite and destabilization of calcite (slow heterogeneous formation), or by the destabilization and inhibition of calcite formation (spherulitic growth)

Polyethers for biomedical applications. Polymerization of propylene oxide by organozinc/organotin catalysts

The polymerization of propylene oxide to obtain a high-molecular-weight polymer with an atactic structure required for the application as artificial blood vessels was investigated using combinations of organozinc and organotin compounds as catalyst. The composition of the most active catalyst, resulting from the reaction of diphenyltin sulfide with bis(3-dimethyl-aminopropyl)zinc, was found to be R(C6H5)2Sn(SZn)2R with R = (CH2)3N(CH3)2. Using this catalyst, an anionic coordination polymerization was observed with neither stereoselectivity nor living type or cationic features. At low catalyst concentration (0,03 mol-% Zn) a high-molecular-weight poly(propylene oxide) (PPOX) was obtained in 80-90% yield ([bar M ]w = 500000; 40% isotactic). Lowering of the catalyst concentration and increasing the polymerization temperature changed the kinetics and the stereochemistry of the polymerization leading to polymers of lower molecular weight and to a decrease in the isotactic PPOX fraction to 20%, probably due to an association of the catalytic species

Wall thickness of the carotid artey as an indicator of generalized atherosclerosis : the Rotterdam study

The past decades have led to a better understanding of the etiology and pathogenesis of atherosclerosis and its clinical sequelae. Several risk factors have been identified that promote atherosclerosis to develop and of which it is currently known that their presence increases the risk of cardiovascular disease. At present, cardiovascular disease is believed to be caused by an interplay of advanced atherosclerotic vessel wall changes, stenosis and thrombosis. However, the question why some people suffer from a cardiovascolar event whereas others may be SPared from SYffiptomatic cardiovascular disease remains unanswered. This is in particular important for subjects of older age, since in these subjects some extent of atherosclerosis is already present. Non-invasive techniques to accurately assess atherosclerotic vessel wall abnormalities may be used to smdy the atherosclerotic process in population-based studies in order to gain further insight in factors that initiate the atherosclerotic process, lead to progression of atherosclerosis, and cause disease to manifest itself in the absence or presence of atherosclerotic vessel wall abnormalities. High resolution B-mode ultrasonography of carotid arteries may provide a tool to study signs of early and advanced atherosclerosis, to monitor the process of development of atherosclerosis and to study factors which promote development and progression of atherosclerotic vessel wall disease and subsequent clinical cardiovascular disease in populations at large.'-" The main objectives of the studies presented in this thesis were to evaluate the feasibility of non-invasive assessment of hemodynamically important stenosis of the carotid artery and common carotid intima-media thickness, in an elderly non-hospitalized population; to study the value of increased intima-media thickness of the distal common carotid artery as an indicator of generalized atherosclerosis; to study determinants of increased common carotid intima-media thickness. In chapter 3, a general outline is given of the principles of the ultrasound technique and a detailed description of the ultrasound reading protocol as it is used in the Rotterdam Study is provided. Furthermore, the reproducibility of the ultrasonographic measurements of common carotid intima-media thickness is presented in this chapter. The associations between intima-media thickness of the distal common carotid artery and indicators of atherosclerosis in other arteries are descnoed in chapter 4. Results from studies on the association between common carotid intima-media thickness and cardiovascular risk factors are discussed in chapter 5, whereas chapter 6 deals with the prevalence and determinants of carotid atherosclerosis diagnosed as hemodynamically important stenosis. The findings presented in chapter 7 concern the association between cerebral white matter lesions and non-invasively assessed atherosclerosi

Investigation of paramagnetic saturation in lanthanum manganese nitrate

Paramagnetic saturation of lanthanum manganese nitrate, La2Mn3(NO3)12·24H2O, has been investigated at liquid He temperatures in a static as well as a dynamical way. With the aid of the molecular-field theory the Casimir and Du Pré dispersion and absorption curves are adapted explicitly to the phenomenon of saturation. A satisfactory agreement has been observed between theory and experiment

Supporting sustainable urban planning and development: three approaches

Cities are among the most complex of man-made systems. Interventions in these systems are never simple. The essential cooperation between all stakeholders can be improved by tools that clarify urban development processes and quantify impacts. TNO and its partners have developed three promising decision support systems

Older people in dental practice:Oral health and oral health care

The study in community-dwelling older people who still visit the dental practice shows that they are relatively healthy and in most cases have a higher socioeconomic status. Nevertheless, these older people also show an increase in health problems, the number of medicines being used and the number of oral health problems as they get older. The tipping point in most cases is around the age of 75. In the assessments of the oral health status, older patients themselves assess their own oral health more positively than the dentists do. The most frequently chosen treatment strategy focuses on conservation of the dentition. Up until now, there is little collaboration with other health care professionals involved in the care of older persons. The barriers perceived in dental practice, in providing oral health care to older people are mainly related to their health problems, the sometimes occurring challenging behaviour and the poor performance of daily oral hygiene care by older people. Previously, a lack of knowledge about the (side) effects of medications used by older people appeared to be a barrier among dentists as well. The study also showed that the current financial reimbursement for providing oral health care is not a significant barrier in practice. It is proposed to advocate basic dental care insurance from the age of 75 and to collaborate with other disciplines to improve oral health care for older people