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Blubber is a highly specialized and dynamic tissue unique to marine mammals and presents a reflection of the individuals' nutrition, environment, and life history traits. Few studies have investigated the histomorphology of cetacean blubber in subtropical environments. The aim of this study was to investigate the blubber histomorphology of three different dolphin species off the subtropical KwaZulu-Natal coast, South Africa, using adipocyte cell size, number, and density. Blubber tissue samples from the saddle area of 43 incidentally bycaught animals (four Sousa plumbea, 36 Tursiops aduncus, and three Delphinus delphis) were used to compare cell parameters between blubber layers. Samples were divided into the upper third (corresponding to the superficial layer closest to the epidermis), middle third, and lower third (corresponding to the deep layer). For T. aduncus, factors potentially affecting blubber histomorphology, such as sex, age class, and season, were also assessed. Our results showed that no stratification was present in S. plumbea, which could be ascribed to the species' warmer inshore habitat, large body size, and apparent lower mobility. For T. aduncus and D. capensis, however, blubber stratification was determined, characterized by a gradual transition of cell size, number, and density between layers rather than clearly defined layers. Significant differences in adipocyte cell number and density were found for different sexes and age classes of T. aduncus. However, there were no significant differences between seasons, which was attributed to the small temperature differences between seasons. This study represents the first investigation of odontocete blubber histomorphology in subtropical waters. It is recommended that future studies investigate blubber lipid content, while also taking into consideration the reproductive status of the females and the temperature range of their study area. It is hoped that our results, in conjunction with histopathology and other health indicators, could assist in assessing health and body condition., (© 2022 Wiley Periodicals LLC.)

Background: Human embryonic stem cells (hESC) as a source for the development of advanced therapy medicinal products are considered for treatment of Parkinson's disease (PD). Research has shown promising results and opened an avenue of great importance for patients who currently lack a disease modifying therapy. The use of hESC has given rise to moral concerns and been the focus of often heated debates on the moral status of human embryos. Approval for marketing is still pending., Objective: To Investigate the perspectives and concerns of patients with PD, patients being the directly concerned stakeholders in the ethical discussion., Methods: Qualitative semi-structured interviews related to this new therapy in seventeen patients from two Swedish cities., Results: The participants expressed various interests related to the use of human embryos for development of medicinal therapies; however, overall, they were positive towards the use of hESC for treatment of PD. It was deemed important that the donating woman or couple made the choice to donate embryos voluntarily. Furthermore, there were concerns that the industry does not always prioritise the patient over profit; thus, transparency was seen as important., (© 2022. The Author(s).)

Cellular senescence is a state of stable growth arrest and a desired outcome of tumor suppressive interventions. Treatment with many anti-cancer drugs can cause premature senescence of non-malignant cells. These therapy-induced senescent cells can have pro-tumorigenic and pro-disease functions via activation of an inflammatory secretory phenotype (SASP). Inhibitors of cyclin-dependent kinases 4/6 (CDK4/6i) have recently proven to restrain tumor growth by activating a senescence-like program in cancer cells. However, the physiological consequence of exposing the whole organism to pharmacological CDK4/6i remains poorly characterized. Here, we show that exposure to CDK4/6i induces non-malignant cells to enter a premature state of senescence dependent on p53. We observe in mice and breast cancer patients that the CDK4/6i-induced senescent program activates only a partial SASP enriched in p53 targets but lacking pro-inflammatory and NF-κB-driven components. We find that CDK4/6i-induced senescent cells do not acquire pro-tumorigenic and detrimental properties but retain the ability to promote paracrine senescence and undergo clearance. Our results demonstrate that SASP composition is exquisitely stress-dependent and a predictor for the biological functions of different senescence subsets., (© 2022 The Authors. Published under the terms of the CC BY 4.0 license.)

Cellular senescence is a state of stable proliferative arrest triggered by damaging signals. Senescent cells persist during aging and promote age-related pathologies via the pro-inflammatory senescence-associated secretory phenotype (SASP), whose regulation depends on environmental factors. In vivo, a major environmental variable is oxygenation, which varies among and within tissues. Here, we demonstrate that senescent cells express lower levels of detrimental pro-inflammatory SASP factors in physiologically hypoxic environments, as measured in culture and in tissues. Mechanistically, exposure of senescent cells to low-oxygen conditions leads to AMPK activation and AMPK-mediated suppression of the mTOR-NF-κB signaling loop. Finally, we demonstrate that treatment with hypoxia-mimetic compounds reduces SASP in cells and tissues and improves strength in chemotherapy-treated and aged mice. Our findings highlight the importance of oxygen as a determinant for pro-inflammatory SASP expression and offer a potential new strategy to reduce detrimental paracrine effects of senescent cells., Competing Interests: Declaration of interests M.D. is scientific co-founder, advisor, and shareholder of Cleara Biotech. However, the manuscript was not influenced or funded by Cleara Biotech., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Aging is characterized by a progressive loss of tissue integrity and functionality due to disrupted homeostasis. Molecular oxygen is pivotal to maintain tissue functions, and aerobic species have evolved a sophisticated sensing system to ensure proper oxygen supply and demand. It is not surprising that aberrations in oxygen and oxygen-associated pathways subvert health and promote different aspects of aging. In this review, we discuss emerging findings on how oxygen-sensing mechanisms regulate different cellular and molecular processes during normal physiology, and how dysregulation of oxygen availability lead to disease and aging. We describe various clinical manifestations associated with deregulation of oxygen balance, and how oxygen-modulating therapies and natural oxygen oscillations influence longevity. We conclude by discussing how a better understanding of oxygen-related mechanisms that orchestrate aging processes may lead to the development of new therapeutic strategies to extend healthy aging., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Radiotherapy for head and neck cancer is associated with impairment of salivary gland function and consequent xerostomia, which has a devastating effect on the quality of life of the patients. The mechanism of radiation-induced salivary gland damage is not completely understood. Cellular senescence is a permanent state of cell cycle arrest accompanied by a secretory phenotype which contributes to inflammation and tissue deterioration. Genotoxic stresses, including radiation-induced DNA damage, are known to induce a senescence response. Here, we show that radiation induces cellular senescence preferentially in the salivary gland stem/progenitor cell niche of mouse models and patients. Similarly, salivary gland-derived organoids show increased expression of senescence markers and pro-inflammatory senescence-associated secretory phenotype (SASP) factors after radiation exposure. Clearance of senescent cells by selective removal of p16Ink4a-positive cells by the drug ganciclovir or the senolytic drug ABT263 lead to increased stem cell self-renewal capacity as measured by organoid formation efficiency. Additionally, pharmacological treatment with ABT263 in mice irradiated to the salivary glands mitigates tissue degeneration, thus preserving salivation. Our data suggest that senescence in the salivary gland stem/progenitor cell niche contributes to radiation-induced hyposalivation. Pharmacological targeting of senescent cells may represent a therapeutic strategy to prevent radiotherapy-induced xerostomia.

Calorie restriction (CR) is an effective strategy to delay the onset and progression of aging phenotypes in a variety of organisms. Several molecular players are involved in the anti-aging effects of CR, but mechanisms of regulation are poorly understood. Cellular senescence-a cellular state of irreversible growth arrest-is considered a basic mechanism of aging. Senescent cells accumulate with age and promote a number of age-related pathologies. Whether environmental conditions such as diet affect the accumulation of cellular senescence with age is still unclear. Here, we show that a number of classical transcriptomic markers of senescent cells are reduced in adult but relatively young mice under CR. Moreover, we demonstrate that such senescence markers are not induced in the colon of middle-age human volunteers under CR in comparison with age-matched volunteers consuming normal Western diets. Our data support the idea that the improvement in health span observed in different organisms under CR might be partly due to a reduction in the number of senescent cells., (© 2018 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.)

Inhaled nitric oxide (NO) and other cGMP- or cAMP-dependent pulmonary vasodilators are often used in combination for the treatment of the persistent pulmonary hypertension of the newborn syndrome. There is in vitro evidence to indicate that NO downregulate the pulmonary vascular response to cGMP-dependent agonists raising concern as to whether a synergistic effect is observed when employing a combined strategy in newborns. Hypothesizing that a synergistic effect is absent, we evaluated newborn and juvenile rat pulmonary arteries to determine the individual and combined vasodilatory effect of cGMP- and cAMP-dependent agonists. In precontracted near-resistance pulmonary arteries, the addition of sildenafil reduced vasorelaxation response to NO donor S-nitroso-N-acetyl penicillamine (SNAP). A similar decrease in SNAP-induced vasodilation was observed in arteries pretreated with BAY 41-2272 (10(-9) M), a soluble guanylate cyclase stimulator cGMP, and its downstream protein kinase activator. cGMP also reduced the vasorelaxant response to the cAMP-dependent forskolin. Inhibition of endogenous vascular NO generation enhanced SNAP-induced relaxation. The present data suggest that the mechanism involved in the cGMP desensitization to other relaxant agonists involves downregulation of the small heat shock protein HSP20 and is evident in rat pulmonary and systemic vascular smooth muscle cells. In newborn rats with chronic hypoxia-induced pulmonary hypertension, the combination of sildenafil and inhaled NO resulted in a lesser reduction in pulmonary vascular resistance compared with their individual effect. These data suggest that clinical exposure to one cGMP-dependent pulmonary vasodilator may affect the response to other cGMP- or cAMP-mediated agonists.

Sustained therapeutic hypercapnia prevents pulmonary hypertension in experimental animals, but its rescue effects on established disease have not been studied. Therapies that inhibit Rho-kinase (ROCK) and/or augment nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signaling can reverse or prevent progression of chronic pulmonary hypertension. Our objective in the present study was to determine whether sustained rescue treatment with inhaled CO(2) (therapeutic hypercapnia) would improve structural and functional changes of chronic hypoxic pulmonary hypertension. Spontaneously breathing pups were exposed to normoxia (21% O(2)) or hypoxia (13% O(2)) from postnatal days 1-21 with or without 7% CO(2) (Pa(CO(2)) elevated by ∼25 mmHg) or 10% CO(2) (Pa(CO(2)) elevated by ∼40 mmHg) from days 14 to 21. Compared with hypoxia alone, animals exposed to hypoxia and 10% CO(2) had significantly (P < 0.05) decreased pulmonary vascular resistance, right-ventricular systolic pressure, right-ventricular hypertrophy, and medial wall thickness of pulmonary resistance arteries as well as decreased lung phosphodiesterase (PDE) V, RhoA, and ROCK activity. Rescue treatment with 10% CO(2), or treatment with a ROCK inhibitor (15 mg/kg ip Y-27632 twice daily from days 14 to 21), also increased pulmonary arterial endothelial nitric oxide synthase and lung NO content. In contrast, cGMP content and cGMP-dependent protein kinase (PKG) activity were increased by exposure to 10% CO(2), but not by ROCK inhibition with Y-27632. In vitro exposure of pulmonary artery smooth muscle cells to hypercapnia suppressed serum-induced ROCK activity, which was prevented by inhibition of PKG with Rp-8-Br-PET-cGMPS. We conclude that sustained hypercapnia dose-dependently inhibited ROCK activity, augmented NO-cGMP-PKG signaling, and led to partial improvements in the hemodynamic and structural abnormalities of chronic hypoxic PHT in juvenile rats. Increased PKG content and activity appears to play a major upstream role in CO(2)-induced suppression of ROCK activity in pulmonary arterial smooth muscle.

Chronic pulmonary hypertension in infancy and childhood frequently culminates in right-ventricular (RV) failure and early death. Current management may include prolonged treatment with inhaled nitric oxide (iNO). Our objective was to examine the effects of iNO on established chronic hypoxic pulmonary hypertension in juvenile rats, a model of chronic neonatal pulmonary hypertension characterized by increased pulmonary vascular resistance, vascular remodeling (RV hypertrophy and arterial medial wall thickening), and significant RV dysfunction. Pups were exposed to air or hypoxia (13% O(2)) from postnatal day 1 to 21 while receiving iNO (20 ppm) from day 14 to 21. In hypoxia-exposed animals, treatment with iNO decreased pulmonary vascular resistance, but did not augment RV output or reverse vascular remodeling. In addition, RV output was significantly reduced in air-exposed iNO-treated pups. Nitrotyrosine (a marker of peroxynitrite-mediated reactions), apoptosis, and expression of nitric oxide synthases 1 and 2 were increased in RV (but not left-ventricular) tissue from both air- and hypoxia-exposed pups treated with iNO. Concurrent treatment with a peroxynitrite decomposition catalyst (FeTPPS, 30 mg/kg/day, ip) prevented apoptosis and completely normalized RV output in iNO-exposed animals. Our results provide the first evidence that iNO may adversely impact the right ventricle through increased local generation of peroxynitrite., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Recently, considerable attention has been given to the understanding of texture attributes that cannot directly be related to physical properties of food, such as creamy, crumbly and watery. The perception of these attributes is strongly related to the way the food is processed during food intake, mastication, swallowing of it and during the cleaning of the mouth after swallowing. Moreover, their perception is modulated by the interaction with other basic attributes, such as taste and aroma attributes (e.g. sourness and vanilla). To be able to link the composition and structure of food products to more complicated texture attributes, their initial physical/colloid chemical properties and the oral processing of these products must be well understood. Understanding of the processes in the mouth at colloidal length scales turned out to be essential to grasp the interplay between perception, oral physiology and food properties. In view of the huge differences in physical chemical properties between food products, it is practical to make a distinction between solid, semi-solid, and liquid food products. The latter ones are often liquid dispersions of emulsion droplets or particles in general. For liquid food products for instance flow behaviour and colloidal stability of dispersed particles play a main role in determining their textural properties. For most solid products stiffness and fracture behaviour in relation to water content are essential while for semi-solids a much larger range of mechanical properties will play a role. Examples of colloidal aspects of texture perception will be discussed for these three categories of products based on selected sensory attributes and/or relevant colloidal processes. For solid products some main factors determining crispness will be discussed. For crispiness of dry cellular solid products these are water content and the architecture of the product at mesoscopic length scales (20-1000 microm). In addition the distribution of water at mesoscopic length scales was found to be important. For semi-solid foods, sensory characteristics as spreadability, watery and crumbliness are primarily determined by food properties at mesoscopic length scales. Crumbliness is directly related to the formation of free running cracks that occur during eating of the product. Exudation of the continuous liquid phase of gels during compression gives rise to watery/juicy sensory attributes. For liquid food products, colloidal interactions of emulsion droplets, particles, proteins, and polysaccharides with saliva and oral surfaces were found to affect texture characteristics as creaminess, fattiness, roughness and astringency.

Background: The prevalence of overweight is increasing globally and has become a serious health problem. Low-grade chronic inflammation in overweight subjects is thought to play an important role in disease development. Novel tools to understand these processes are needed. Metabolic profiling is one such tool that can provide novel insights into the impact of treatments on metabolism., Methodology: To study the metabolic changes induced by a mild anti-inflammatory drug intervention, plasma metabolic profiling was applied in overweight human volunteers with elevated levels of the inflammatory plasma marker C-reactive protein. Liquid and gas chromatography mass spectrometric methods were used to detect high and low abundant plasma metabolites both in fasted conditions and during an oral glucose tolerance test. This is based on the concept that the resilience of the system can be assessed after perturbing a homeostatic situation., Conclusions: Metabolic changes were subtle and were only detected using metabolic profiling in combination with an oral glucose tolerance test. The repeated measurements during the oral glucose tolerance test increased statistical power, but the metabolic perturbation also revealed metabolites that respond differentially to the oral glucose tolerance test. Specifically, multiple metabolic intermediates of the glutathione synthesis pathway showed time-dependent suppression in response to the glucose challenge test. The fact that this is an insulin sensitive pathway suggests that inflammatory modulation may alter insulin signaling in overweight men.

Crispness is an important quality characteristic of dry solid food products such as crispy rolls. Its retention is directly related to the kinetics of water uptake by the crust. In this study, a method for the evaluation of the water sorption kinetics in bread crust is proposed. Two different sorption experiments were used: an oscillatory sorption test and a sorption test in which the air relative humidity (RH) was increased stepwise. These two experiments had different time scales, which made it possible to get a better understanding of the mechanisms involved. Results show that the adsorption and desorption dynamics of the oscillatory sorption test could be described by a single exponential in time. The water uptake rate ( k) was one of the fitting parameters. A maximum in the water uptake rate was found for a RH value between 50 and 70%. The rate parameters of the experiment where RH was increased stepwise were around a factor 10 lower than those derived from oscillatory sorption experiments. This is an important factor when designing experiments for the determination of water uptake rates. In addition, also a parameter describing the time dependence of the rate parameters of the oscillatory sorption experiment was calculated (C), again by fitting a single exponential to the rate parameters. C was in the same range as the rate parameter of the isotherm experiment. This indicates that different (relaxation) processes are acting at the same time in the bread crust during water uptake.

A detailed study was performed of the fracture behavior of toasted rusk rolls, a cellular solid food, at different water activities and morphologies. We find that the energies of the emitted sound pulses follow Gutenberg-Richter power laws with characteristic exponents b ~ 1.5 . The scaling exponents varied only within a range of 0.2 when the method of fracture, humidity, or morphology was changed. However, differences in b were observed, indicating nonuniversal behavior, that seems to be related to morphology and water activity. Also, power law scaling behavior was observed for the waiting time distributions with an exponent a ~ 1.9.

Pulmonary hypertension (PHT) in neonates is often refractory to the current best therapy, inhaled nitric oxide (NO). The utility of a new class of pulmonary vasodilators, Rho-kinase (ROCK) inhibitors, has not been examined in neonatal animals. Our objective was to examine the activity and expression of RhoA/ROCK in normal and injured pulmonary arteries and to determine the short-term pulmonary hemodynamic (assessed by pulse wave Doppler) effects of ROCK inhibitors (15 mg/kg ip Y-27632 or 30 mg/kg ip fasudil) in two neonatal rat models of chronic PHT with pulmonary vascular remodeling (chronic hypoxia, 0.13 Fi(O(2)), or 1 mg.kg(-1).day(-1) ip chronic bleomycin for 14 days from birth). Activity of the RhoA/ROCK pathway and ROCK expression were increased in hypoxia- and bleomycin-induced PHT. In both models, severe PHT [characterized by raised pulmonary vascular resistance (PVR) and impaired right ventricular (RV) performance] did not respond acutely to inhaled NO (20 ppm for 15 min) or to a single bolus of a NO donor, 3-morpholinosydnonimine hydrochloride (SIN-1; 2 mug/kg ip). In contrast, a single intraperitoneal bolus of either ROCK inhibitor (Y-27632 or fasudil) completely normalized PVR but had no acute effect on RV performance. ROCK-mediated vasoconstriction appears to play a key role in chronic PHT in our two neonatal rat models. Inhibitors of ROCK have potential as a testable therapy in neonates with PHT that is refractory to NO.

Based on earlier reported surface rheological behaviour two factors appeared to be important for the functional behaviour of mixed protein/polysaccharide adsorbed layers at air/water interfaces: (1) protein/polysaccharide mixing ratio and (2) formation history of the layers. In this study complexes of beta-lactoglobulin (positively charged at pH 4.5) and low methoxyl pectin (negatively charged) were formed at two mixing ratios, resulting in negatively charged and nearly neutral complexes. Neutron reflection showed that adsorption of negative complexes leads to more diffuse layers at the air/water interface than adsorption of neutral complexes. Besides (simultaneous) adsorption of protein/polysaccharide complexes, a mixed layer can also be formed by adsorption of (protein/)polysaccharide (complexes) to a pre-formed protein layer (sequential adsorption). Despite similar bulk concentrations, adsorbed layer density profiles of simultaneously and sequentially formed layers were persistently different, as illustrated by neutron reflection analysis. Time resolved fluorescence anisotropy showed that the mobility of protein molecules at an air/water interface is hampered by the presence of pectin. This hampered mobility of protein through a complex layer could account for differences observed in density profiles of simultaneously and sequentially formed layers. These insights substantiated the previously proposed organisations of the different adsorbed layers based on surface rheological data.

Objective: To determine the effect of folic acid, vitamin B(6) and B(12) fortified spreads on the blood concentrations of these vitamins and homocysteine., Design and Setting: A 6-week randomized, double-blinded, placebo-controlled, parallel trial carried out in a clinical research center., Subjects: One hundred and fifty healthy volunteers (50% males)., Interventions: For 6 weeks, the subjects consumed the test spreads (20 g/day): containing per 20 g (1) 200 microg folic acid, 2 microg vitamin B(12) and 1 mg vitamin B(6), or (2) 400 microg folic acid, 2 microg vitamin B(12) and 1 mg vitamin B(6) or (3) no B-vitamins (control spread)., Results: The B-vitamin status increased on using the test spreads, with the largest effect on the serum folate concentration: 48% in men and 58% in women on spread 1 and 92 and 146%, respectively, on spread 2 (P-values all <0.05). The plasma homocysteine decreased in the groups treated with the fortified spreads as compared to the control group. Average decreases were for males: 0.7+/-1.5 micromol/l (6.8%) on spread 1 and 1.7+/-1.7 micromol/l (17.6%) on spread 2 and for females: 1.4+/-1.2 micromol/l (14.2%) and 2.4+/-2.0 micromol/l (23.3%), respectively (P-values all <0.05)., Conclusions: Consumption of a spread fortified with folic acid, vitamin B(6) and vitamin B(12) for 6 weeks significantly increases the blood concentrations of these vitamins and significantly decreases the plasma concentration of homocysteine. Fortified staple foods like spreads can contribute to the lowering of homocysteine concentrations.

In this work, water sorption kinetics of bread crust are described using an oscillatory sorption test in combination with a Langmuir type equation. Both kinetic and thermodynamic information could be obtained at the same time. An advantage of applying a Langmuir type equation for a quantitative description of the water uptake kinetics is that no prior knowledge is necessary with respect to shape and surface area of the sample. It was shown that adsorption and desorption of water to the bread crust particle surface is much faster than the experimental time used (15 min at minimum). From this, we may conclude that diffusion of water into the solid matrix is the rate-limiting step in the water sorption process. The method also allows one to calculate a Gibbs free energy. The method is suitable for use up to relative humidities of 60%.

There is a large interest in mixed protein/polysaccharide layers at air-water and oil-water interfaces because of their ability to stabilize foams and emulsions. Mixed protein/polysaccharide adsorbed layers at air-water interfaces can be prepared either by adsorption of soluble protein/polysaccharide complexes or by sequential adsorption of complexes or polysaccharides to a previously formed protein layer. Even though the final protein and polysaccharide bulk concentrations are the same, the behavior of the adsorbed layers can be very different, depending on the method of preparation. The surface shear modulus of a sequentially formed beta-lactoglobulin/pectin layer can be up to a factor of 6 higher than that of a layer made by simultaneous adsorption. Furthermore, the surface dilatational modulus and surface shear modulus strongly (up to factors of 2 and 7, respectively) depend on the bulk -lactoglobulin/pectin mixing ratio. On the basis of the surface rheological behavior, a mechanistic understanding of how the structure of the adsorbed layers depends on the protein/polysaccharide interaction in bulk solution, mixing ratio, ionic strength, and order of adsorption to the interface (simultaneous or sequential) is derived. Insight into the effect of protein/polysaccharide interactions on the properties of adsorbed layers provides a solid basis to modulate surface rheological behavior.

A proof-of-concept study to assess the safety and efficacy of a traditional Chinese medicine formula as treatment for primary dysmenorrhea showed no statistically significant benefit over placebo. However, some efficacy parameters suggested possible superiority of the active treatment and so a larger study needs to be performed to determine whether this remedy has a role in the treatment of dysmenorrhea.

Background: Betaine (trimethylglycine) lowers plasma homocysteine, a possible risk factor for cardiovascular disease. However, studies in renal patients and in obese individuals who are on a weight-loss diet suggest that betaine supplementation raises blood cholesterol; data in healthy individuals are lacking. Such an effect on cholesterol would counteract any favourable effect on homocysteine. We therefore investigated the effect of betaine, of its precursor choline in the form of phosphatidylcholine, and of the classical homocysteine-lowering vitamin folic acid on blood lipid concentrations in healthy humans., Methods and Findings: We measured blood lipids in four placebo-controlled, randomised intervention studies that examined the effect of betaine (three studies, n = 151), folic acid (two studies, n = 75), and phosphatidylcholine (one study, n = 26) on plasma homocysteine concentrations. We combined blood lipid data from the individual studies and calculated a weighted mean change in blood lipid concentrations relative to placebo. Betaine supplementation (6 g/d) for 6 wk increased blood LDL cholesterol concentrations by 0.36 mmol/l (95% confidence interval: 0.25-0.46), and triacylglycerol concentrations by 0.14 mmol/l (0.04-0.23) relative to placebo. The ratio of total to HDL cholesterol increased by 0.23 (0.14-0.32). Concentrations of HDL cholesterol were not affected. Doses of betaine lower than 6 g/d also raised LDL cholesterol, but these changes were not statistically significant. Further, the effect of betaine on LDL cholesterol was already evident after 2 wk of intervention. Phosphatidylcholine supplementation (providing approximately 2.6 g/d of choline) for 2 wk increased triacylglycerol concentrations by 0.14 mmol/l (0.06-0.21), but did not affect cholesterol concentrations. Folic acid supplementation (0.8 mg/d) had no effect on lipid concentrations., Conclusions: Betaine supplementation increased blood LDL cholesterol and triacylglycerol concentrations in healthy humans, which agrees with the limited previous data. The adverse effects on blood lipids may undo the potential benefits for cardiovascular health of betaine supplementation through homocysteine lowering. In our study phosphatidylcholine supplementation slightly increased triacylglycerol concentrations in healthy humans. Previous studies of phosphatidylcholine and blood lipids showed no clear effect. Thus the effect of phosphatidylcholine supplementation on blood lipids remains inconclusive, but is probably not large. Folic acid supplementation does not seem to affect blood lipids and therefore remains the preferred treatment for lowering of blood homocysteine concentrations.

The relation between mechanical film properties of various adsorbed protein layers at the air/water interface and intrinsic stability of the corresponding proteins is discussed. Mechanical film properties were determined by surface deformation in shear and dilation. In shear, fracture stress, sigma(f), and fracture strain, gamma(f), were determined, as well as the relaxation behavior after macroscopic fracture. The dilatational measurements were performed in a Langmuir trough equipped with an infra-red reflection absorption spectroscopy (IRRAS) accessory. During compression and relaxation of the surface, the surface pressure, Pi, and adsorbed amount, Gamma (determined from the IRRAS spectra), were determined simultaneously. In addition, IRRAS spectra revealed information on conformational changes in terms of secondary structure. Possible correlations between macroscopic film properties and intrinsic stability of the proteins were determined and discussed in terms of molecular dimensions of single proteins and interfacial protein films. Molecular properties involved the area per protein molecule at Pi approximately 0 mN/m (A(0)), A(0)/M (M = molecular weight) and the maximum slope of the Pi-Gamma curves (dPi/dGamma). The differences observed in mechanical properties and relaxation behavior indicate that the behavior of a protein film subjected to large deformation may vary widely from predominantly viscous (yielding) to more elastic (fracture). This transition is also observed in gradual changes in A(0)/M. It appeared that in general protein layers with high A(0)/M have a high gamma(f) and behave more fluidlike, whereas solidlike behavior is characterized by low A(0)/M and low gamma(f). Additionally, proteins with a low A(0)/M value have a low adaptability in changing their conformation upon adsorption at the air/water interface. Both results support the conclusion that the hardness (internal cohesion) of protein molecules determines predominantly the mechanical behavior of adsorbed protein layers.

This paper describes an experimental comparison of microstructure, rheology, and demixing of bridging- and depletion-flocculated oil-in-water emulsions. Confocal scanning laser microscopy imaging showed that bridging-flocculated emulsions were heterogeneous over larger length scales than depletion-flocculated emulsions. As a consequence, G' as determined from diffusing wave spectroscopy (DWS) corresponded well with G' as measured macroscopically for the depletion-flocculated emulsions, but this correspondence was not found for the bridging-flocculated emulsions. The heterogeneity of bridging-flocculated emulsions was confirmed by DWS-echo measurements, indicating that their structure breaks up into large fragments upon oscillatory shear deformation larger than 1%. Depletion- and bridging-flocculated emulsions showed a different scaling of the storage modulus with the volume fraction of oil and a difference in percolation threshold volume fraction. These differences will be discussed on the basis of the two types of droplet-droplet interactions studied. Gravity-induced demixing occurred in both emulsions, but the demixing processes differed. After preparation of bridging-flocculated emulsions, serum immediately starts to separate, whereas depletion-flocculated systems at polysaccharide concentrations in the overlap regime usually showed a delay time before demixing. The delay time was found to scale with the network permeability, B; the viscosity, eta, of the aqueous phase; and the density difference between oil and water, Deltarho, as tdelay approximately B(-1)etaDeltarho(-1). The results are in line with the mechanism proposed by Starrs et al. (J. Phys.: Condens. Matter 2002, 14, 2485-2505), where erosion of the droplet network leads to widening of the channels within the droplet networks, facilitating drainage of liquid.

Background: A high plasma total homocysteine (tHcy) concentration is a risk factor for cardiovascular disease. The increase in tHcy induced by methionine, the sole dietary precursor of homocysteine, might be modulated by other amino acids present in dietary proteins., Objectives: Our objectives were to compare the postprandial effect of free and dietary methionine on plasma tHcy concentrations and to investigate whether serine and cystine modify the effect of free methionine on tHcy., Design: We conducted a randomized crossover trial in 24 healthy men. Each subject ingested 4 meals on separate days, which were separated by 1 wk. tHcy concentrations were measured in the fasting state and at 2, 4, 6, 8, 10, and 24 h after meal ingestion. The meals were 1) a low-protein meal fortified with 30 mg methionine/kg body wt (reference, denoted by "Met"), 2) meal 1 additionally fortified with 60.6 mg serine/kg body wt (MetSer), 3) meal 1 additionally fortified with 12.3 mg cystine/kg body wt (MetCys), and 4) a protein-rich meal containing 30 mg methionine, 60.6 mg serine, and 12.3 mg cystine per kg body wt (Protein)., Results: The mean (+/-SD) fasting tHcy concentration was 9.1 +/- 2.7 micromol/L. Mean peak tHcy concentrations were 17.9 +/- 4.5, 14.3 +/- 3.3, 14.8 +/- 3.9, and 11.2 +/- 3.1 micromol/L after Met, MetSer, MetCys, and Protein, respectively. Compared with the mean 24-h area under the tHcy-by-time curve after Met, the mean curves after MetSer, MetCys, and Protein were 37%, 32%, and 77% smaller, respectively (all P < 0.0005)., Conclusions: Dietary methionine increases tHcy much less than does free methionine. Serine and cystine attenuate the tHcy-raising effect of free methionine. Thus, dietary proteins with a high content of serine or cystine relative to methionine may lead to lower postprandial tHcy responses.

The coarsening of emulsion droplets by Ostwald ripening is studied by means of numerical simulations in which time-dependent (elastic) interfacial behaviour is taken into account. Theoretical calculations on the dissolution of a single emulsion droplet in an infinite medium at saturated conditions show that the dissolution process can be stopped only when the interfacial tension goes to zero. When interfacial stress relaxation is included, which prevents a continuous zero interfacial tension, no stabilisation of the dissolution process is observed and the droplet dissolves completely. In the case of an ensemble of droplets, numerical calculations on the coarsening of emulsion droplets with finite interfacial elasticity show that a stable situation occurs at finite interfacial tensions of the droplets. This applies for a closed system with the same assumptions as those made in the Lifshitz-Slyozov-Wagner (LSW) theory. The coarsening behaviour strongly depends on the saturation of the dispersed phase in the continuous phase. If the system is in contact with atmosphere, saturation will finally go to unity and stabilisation will only occur for zero interfacial tension of the droplets. For an ensemble of droplets in a closed system, the calculations show that stress-relaxation of the interface causes the Ostwald-ripening process to continue, so no stable situation is reached. Stabilisation can only be accomplished by adding insoluble species to the dispersed phase, by using particles as stabilisers or by micro-encapsulation of the emulsion droplets by thick insoluble interfacial layers, which have a thickness that is in the order of the radius of the droplet.

High plasma homocysteine is a risk for cardiovascular disease and can be lowered through supplementation with 6 g/d of betaine. However, dietary intake of betaine is approximately 0.5-2 g/d. Therefore, we investigated whether betaine supplementation in the range of dietary intake lowers plasma homocysteine concentrations in healthy adults. Four groups of 19 healthy subjects ingested three doses of betaine or placebo daily for 6 wk. A methionine loading test was performed during run in, on d 1 of betaine supplementation, and after 2 and 6 wk of betaine supplementation. Fasting plasma homocysteine after 6-wk daily intakes of 1.5, 3 and 6 g of betaine was 12% (P < 0.01), 15% (P < 0.002) and 20% (P < 0.0001) less than in the placebo group, respectively. Furthermore, the increase in plasma homocysteine after methionine loading on the 1st d of betaine supplementation was 16% (P < 0.06), 23% (P < 0.008) and 35% (P < 0.0002) less than in the placebo group, respectively, and after 6 wk of supplementation was 23% (P < 0.02), 30% (P < 0.003) and 40% (P < 0.0002) less, respectively. Thus, doses of betaine in the range of dietary intake reduce fasting and postmethionine loading plasma homocysteine concentrations. A betaine-rich diet might therefore lower cardiovascular disease risk.

Background: Bioavailability studies with lycopene have focused on natural sources. A synthetic source has recently become available., Aim of the Study: To determine the relative bioavailabilities of synthetic and tomato-based lycopene in free living volunteers in a single-blind, randomized, placebo-controlled, parallel trial., Methods: Three groups (n=12/group) of healthy, normolipemic male and female subjects with a mean baseline serum lycopene concentration of 0.36 micro mol/L took a dose of 15 mg/day total lycopene for 28 days from either Lycovit 10% (beadlets, BASF, Germany) or Lyc-O-Mato (beads, LycoRed Natural Products, Israel) or a placebo (without lycopene) together with the main meal. The increase in serum lycopene from baseline was used as the parameter of bioavailability., Results: Synthetic and tomato-lycopene resulted in significant increases above baseline of serum total lycopene by 0.58 and 0.57 micro mol/L, trans-lycopene by 0.34 and 0.41 micro mol/L, and total-cis-lycopene by 0.24 and 0.16 micro mol/L, whereas no significant changes were found in the placebo treatment. The mean serum total lycopene response to synthetic and natural lycopene was not significantly different. Neither lycopene source affected the other serum carotenoids, viz. alpha-carotene, beta-carotene, beta-cryptoxanthin, zeaxanthin and lutein., Conclusion: We conclude that synthetic and natural lycopene are equivalent sources of lycopene and that there is no interaction with other circulating carotenoids.

Background: A high plasma total homocysteine concentration is associated with increased risk of cardiovascular disease. Consumption of unfiltered or filtered coffee raises total homocysteine concentrations in healthy volunteers. The responsible compound, however, is unknown., Objective: The objective was to determine whether caffeine explains the homocysteine-raising effect of coffee., Design: Forty-eight subjects aged 19-65 y completed this randomized crossover study with 3 treatments, each lasting 2 wk. Subjects consumed 6 capsules providing 870 mg caffeine/d (test treatment), 0.9 L paper-filtered coffee providing approximately 870 mg caffeine/d, or 6 placebo capsules. Blood samples were drawn fasting and 4 h after consumption of 0.45 L coffee or 3 capsules., Results: The mean fasting plasma homocysteine concentration after the placebo treatment was 9.6 +/- 3.1 micro mol/L. The caffeine and coffee treatments increased fasting homocysteine by 0.4 micro mol/L (95% CI: 0.1, 0.7; P = 0.04), or 5%, and by 0.9 micro mol/L (95% CI: 0.6, 1.2; P = 0.0001), or 11%, respectively, compared with placebo. The increase in homocysteine concentrations 4 h after consumption of 0.45 L coffee relative to consumption of 3 placebo capsules was 19% (P = 0.0001). Caffeine treatment had a much weaker acute effect on homocysteine (4%; P = 0.09). Effects of caffeine were stronger in women than in men, but the effects of coffee did not differ significantly between men and women., Conclusions: Caffeine is partly responsible for the homocysteine-raising effect of coffee. Coffee, but not caffeine, affects homocysteine metabolism within hours after intake, although the effect is still substantial after an overnight fast.

The influence of pH and ionic strength on gel formation and gel properties of soy protein isolate (SPI) in relation to denaturation and protein aggregation/precipitation was studied. Denaturation proved to be a prerequisite for gel formation under all conditions of pH and ionic strength studied. Gels exhibited a low stiffness at pH >6 and a high stiffness at pH <6. This might be caused by variations in the association/dissociation behavior of the soy proteins on heating as a function of pH, as indicated by the different protein compositions of the dissolved protein after heating. At pH 3-5 all protein seems to participate in the network, whereas at pH >5 less protein and especially fewer acidic polypeptides take part in the network, coinciding with less stiff gels. At pH 7.6, extensive rearrangements in the network structure took place during prolonged heating, whereas at pH 3.8 rearrangements did not occur.

A series of proteins was studied with respect to their ability to form a network at the air/water interface and their suitability as foaming agents and foam stabilizers. Proteins were chosen with a range of structures from flexible to rigid/globular: beta-casein, beta-lactoglobulin, ovalbumin, and (soy) glycinin. Experiments were performed at neutral pH except for glycinin, which was studied at both pH 3 and pH 6.7. The adsorption process was followed with an automated drop tensiometer (ADT). Network forming properties were assessed in terms of surface dilational modulus (determined with the ADT), the critical falling film length (L(still)) and flow rate (Q(still)) below which a stagnant film exists (as measured with the overflowing cylinder technique), and the fracture stress and fracture strain measured in surface shear. It was found that glycinin (pH 3) can form an interfacial gel in a very short time, whereas beta-casein has very poor network-forming properties. Hardly any foam could be produced at the chosen conditions with glycinin (pH 6.7) and with ovalbumin, whereas beta-casein, beta-lactoglobulin, and glycinin (pH 3) were good foaming agents. It seems that adsorption and unfolding rate are most important for foam formation. Once the foam is formed, a rigid network might favor stabilizing the foam.

In this paper the determination of the physical/rheological characteristics is described for a series of commercial galactomannans of which the structural details have been reported previously. Both solubility of the galactomannans and rheological properties of galactomannan solutions and galactomannan/xanthan mixtures were determined. Using a statistical analysis approach an attempt was undertaken to recognize correlations between structural and rheological data. The best correlation found was between the abundance of galactose substituents at a regular distance (type of galactomannan) and the storage modulus (G') of mixed galactomannan/xanthan gels, underscoring the hypothesis that branching hinders the formation of a network with xanthan gum. Also, the G' for the group of locust bean gums correlated with the degree of blockiness, that is, the size and occurrence of nonsubstituted regions on the mannose backbone. In addition, galactomannans displayed an apparent decrease in gelling ability with increasing average molecular weight. That G' also relates to the type of galactomannan can therefore partly be attributed to differences in average molecular weight for the various galactomannan types. However, within the series of locust bean gums tested, also an increase of G' with molecular weight was observed. This can be explained by the decreasing number of loose ends of the polymers and the concomitant increasing efficiency in network participation with increasing molecular weight.

Review of the theoretical and empirical literature on homesickness showed that despite recent advances, scientific understanding of the impact on students of leaving home for college is still limited. Further empirical investigation using standardized measures, structural equation models and including additional mediating/moderating variables is needed. Two studies were thus conducted, one in the Netherlands, and one in the UK. Homesickness was investigated among recent-intake students, using a newly developed instrument, the Utrecht Homesickness Scale. Variables investigated in relationship to homesickness included depression, personality factors (self-liking, competence, self-esteem) and family situation (attachment to family). Homesickness was found to be a common though differentially prevalent phenomenon (approximately 50% in the Netherlands; 80% in the UK). Structural equation models showed that students missed family and friends and had difficulties adjusting to college life. These difficulties were associated with ruminations about home and loneliness, which themselves were associated with depression. There were differences in intensity (UK students were more homesick) and there were gender differences (UK females experienced more homesickness). Both the personality and family situation factors had an impact on homesickness. The results supported the conceptualization of homesickness as a 'mini-grief', to be viewed from theoretical perspectives in the field of loss and bereavement.

Heat-induced gel formation by soy protein isolate at pH 7 is discussed. Different heating and cooling rates, heating times, and heating temperatures were used to elucidate the various processes that occur and to study the relative role of covalent and noncovalent protein interactions therein. Gel formation was followed by dynamic rheological measurements. Heat denaturation was a prerequisite for gel formation. The gelation temperature (84 degrees C) was just above the onset denaturation temperature of glycinin. The stiffness of the gels, measured as the elastic modulus, G', increased with the proportion of denatured protein. An increase in G' was also observed during prolonged heating at 90 degrees C. This increase is explained by the occurrence of rearrangements in the network structure and probably also by further incorporation of protein in the network. The increase in G' upon cooling was thermoreversible indicating that disulfide bond formation and rearrangements do not occur upon cooling.

The entering and spreading of emulsion droplets at quiescent and expanding air/water interfaces was studied using a new apparatus consisting of a modified Langmuir trough in which the air/water interface can be continuously expanded by means of rollers in the place of traditional barriers. When sodium caseinate and whey protein isolate-stabilized emulsion droplets were injected under the surface of sodium caseinate and whey protein isolate solutions, respectively, it appeared that the droplets entered the air/water interface only if the air/water surface pressure did not exceed a threshold value of approximately 15 mN/m. This condition was satisfied either under quiescent conditions for low protein concentrations or by continuous expansion of the interface at higher protein concentrations. According to equilibrium thermodynamics, entering of the droplets and the formation of lenses should occur for all the systems investigated, but this was not observed. At surface pressures higher than approximately 15 mN/m, immersed emulsion droplets were metastable. This is probably due to a kinetic barrier caused by the formation of a thin water film bounded by protein adsorption layers between the emulsion droplet and the air/water interface.

Proteins and low molecular weight (LMW) surfactants are widely used for the physical stabilisation of many emulsions and foam based food products. The formation and stabilisation of these emulsions and foams depend strongly on the interfacial properties of the proteins and the LMW surfactants. Therefore these properties have been studied extensively. In this review an overview is given of interfacial properties of proteins at a mesoscopic scale and the effect of LMW surfactants (emulsifiers) on them. Properties addressed are the adsorbed amount, surface tension (reduction), network formation at interfaces and possible conformational changes during and after adsorption. Special attention is given to interfacial rheological behaviour of proteins at expanding and compressing interfaces, which simulate the behaviour in real emulsions and foams. It will be illustrated that information on interfacial rheological properties, protein conformation and interactions between adsorbed molecules can be obtained by changing experimental conditions. The relation between interfacial rheology and emulsion and foam stabilisation is subsequently addressed. It is concluded that there is a need for new measuring devices that monitor several interfacial properties on a mesoscopic and microscopic scale at the same time, and for physical models describing the various processes of importance for proteins. Real progress will only be possible if both are combined in an innovative way.

This paper describes theoretical calculations of the combined effect of bulk and interfacial rheological properties on dissolution behavior of a bubble in an infinite medium at saturated conditions. Either bulk or interfacial elasticity can stop the bubble dissolution process, and stability criteria are defined for the elastic cases. In the case of an elastic interface with dilation modulus E(d) and a bubble with an initial radius R(0) and initial interfacial tension sigma(0), the bubble is stabilized as it has shrunk to a relative radius of varepsilon=R/R(0)=exp(-sigma(0)/2E(d))). In case of an elastic bulk with modulus G a bubble will shrink until GR(0)=4sigma(0)varepsilon(3)/(1-5varepsilon(4)+4varepsilon(3)) is fulfilled. Bulk and interfacial viscosity can retard the dissolution process if their magnitude exceeds a certain critical value but will never completely stop bubble dissolution. Copyright 2001 Academic Press.

Background: An elevated plasma concentration of total homocysteine is considered to be a strong risk factor for cardiovascular disease. Heavy coffee drinking has been related to high homocysteine concentrations in epidemiologic studies and in one experiment in which healthy subjects drank unfiltered, boiled coffee., Objective: Our goal was to determine whether daily consumption of paper-filtered coffee raises plasma concentrations of total homocysteine in healthy subjects., Design: Twenty-six volunteers (18-53 y of age) consumed 1 L/d of paper-filtered coffee brewed with 70 g regular ground beans or no coffee for 4 wk each in a randomized, crossover design., Results: The mean (+/-SD) plasma concentration of total homocysteine in fasting blood was 8.1 +/- 1.8 micromol/L after abstention from coffee and 9.6 +/- 2.9 micromol/L after 3-4 wk of coffee drinking, a difference of 1.5 micromol/L (95% CI: 0.9, 2.1 micromol/L) or 18% (P: < 0.001). Coffee increased homocysteine concentrations in 24 of 26 individuals. Circulating concentrations of vitamin B-6, vitamin B-12, and folate were unaffected., Conclusion: Drinking large quantities of paper-filtered coffee raises fasting plasma concentrations of total homocysteine in healthy individuals.

This study is focussed on the influence of pH on the gel forming properties of soy protein isolate and purified glycinin in relation to denaturation and aggregation. At pH 7.6 more fine-stranded gels were formed characterised by low G' values, and a smooth, slightly turbid appearance, whereas at pH 3.8 coarse gels were obtained with a high stiffness and a granulated, white appearance. Low G' values, as found at pH 7.6, correlate with a high solubility of glycinin and soy protein isolate (ca. 50%) after heating at low protein concentration. At pH 3.8 all protein precipitated upon heating, which correlates with relatively high G' values. The role of beta-conglycinin during gelation of SPI seems to be minor at pH 7.6, which is indicated by the fact that, in contrast to pH 3.8, notable gel formation did not start upon heat denaturation of beta-conglycinin. Furthermore, the mechanism of gel formation seems to be affected by pH, because at pH 7.6, in contrast to pH 3.8, the disulphide bridge between the acidic and the basic polypeptide of glycinin is broken upon heating.

The mechanical stability of biocatalyst particles in bioreactors is of crucial importance for applications of immobilized-cell technology in bioconversions. The common methods for evaluation of the strength of polymer beads (mostly force-to-fracture or tensile tests) are, however, not yet proven to be relevant for the assessment of their mechanical stability in bioreactors. Therefore, we tested fracture properties of gel materials and investigated their relevance for abrasion in bioreactors. Abrasion of gel beads was assumed to be a continuous fracturing of the bead surface. At first, three rheological properties were considered: stress at fracture; strain at fracture; and the total fracture energy. If stress at fracture is the most important property, beads having a similar fracture energy, but a smaller stress at fracture, would abrade faster in a bioreactor than beads with a larger stress at fracture; if fracture energy the determining factor, beads that require less energy to fracture would abrade faster than those having a larger fracture energy for the same fracture stress. To determine this, beads of kappa-carrageenan and agar (at two different polymer concentrations) were tested for abrasion in four identical bubble columns under the same operating conditions. Agar beads were expected to abrade faster than those of carrageenan because agar had either a lower stress at fracture or a lower fracture energy. However, no correlation between fracture properties and abrasion rate was found in any of the combinations tested. Carrageenan beads abraded faster than those of agar in all combinations. Furthermore, both the stress and strain at fracture of agar and carrageenan beads decreased during the run and those of carrageenan decreased faster, suggesting that the gels are liable to fatigue in different ways. This hypothesis was confirmed by oscillating experiments in which gel samples were subjected to repeated compressions below their fracture levels. Their resistance to compression clearly decreased with the number of oscillations. Fatigue is probably related to the development of microcracks and microfracture propagation within the material. We concluded that: (a) the use of tests based on bead rupture do not provide relevant information on the mechanical stability of gel beads to abrasion; and (b) abrasion of polymer beads is likely to be related to fatigue of the gel materials. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 517-529, 1997.

Objective: To review available information on absorption and further metabolism of different carotenoids in man and to discuss animal models and approaches in the study of carotenoid absorption and metabolism in man., Conclusions: Humans appear to absorb various carotenoids in a relatively non-specific fashion, but absorption kinetics and plasma transport seem to differ among carotenoids, possibly because of differences in polarity. Absorbed beta-carotene for the most part is converted, mainly into retinyl esters, but several details with respect to the cleavage reaction remain to be elucidated. Although interactions among carotenoids do exist, their importance and the mechanisms involved are still unclear. No animal model reflects the human situation for beta-carotene metabolism entirely. Thus, for every research question, the optimal model needs to be selected. Methods available for studying beta-carotene metabolism in man are limited. The most promising methods are the single dose-response in chylomicrons, and plasma responses after dosing with stable isotopes.

The purpose of this study was to examine whether intestinal beta-carotene cleavage activity, measured with the dioxygenase assay, is affected by vitamin A intake and whether this in vitro activity is a determinant of beta-carotene cleavage in vivo, measured in lymph-cannulated rats. Six groups of 10-20 rats were fed a diet with a low, normal or high retinyl palmitate concentration (120 RE, 1200 RE and 12,000 RE per kg, respectively) for 14 to 18 wk, either supplemented or not with 50 mg beta-carotene/kg in the last 6 wk. Intestinal dioxygenase activity was 90% higher (P < 0.05) in the animals fed the unsupplemented low vitamin A diet than in the animals fed the unsupplemented high vitamin A diet, whereas in beta-carotene-supplemented rats intestinal dioxygenase activity was significantly lower than in unsupplemented rats. The molar ratio between retinyl esters and beta-carotene in lymph collected over 8 h after a single intestinal dose of beta-carotene (250 micrograms) to beta-carotene-unsupplemented rats fed the three levels of vitamin A was correlated with intestinal dioxygenase activity (r = 0.66, P = 0.003). Dioxygenase activity in the liver was not affected by the vitamin A concentration of the diet but was 70% higher in the beta-carotene-supplemented rats. Based on the difference in liver vitamin A contents between beta-carotene-supplemented and unsupplemented rats we estimated beta-carotene conversion factors of 9:1 for the rats fed the high vitamin A diet and 4:1 for the rats fed the normal and low vitamin A diets. Intestinal beta-carotene cleavage activity is higher in vitamin A-deficient rats than in rats with a high intake of either vitamin A or beta-carotene. The intestinal dioxygenase activity as measured in vitro is an adequate indicator of in vivo beta-carotene cleavage activity.

In view of controversies about assessment of the beta-carotene cleavage activity, methodological aspects and problems of the dioxygenase assay are described. Using rat and hamster intestinal preparations the method was optimized on retinal formation, the only cleavage product we could demonstrate. It appeared that the cell fraction with the highest cleavage activity was the 9,000 g supernatant (S-9). Maximal retinal formation was obtained with SDS, taurocholate and egg lecithin in the buffer and 3 micrograms beta-carotene dissolved in acetone. Ethanol, THF/DMSO (1:1) or propylene glycol as solvent for beta-carotene reduced retinal formation to 55, 24, and 19%, respectively. Retinal formation increased proportionally with the amount of protein S-9 used and was linear up to 40-60 minutes of incubation. Incubation with alpha-carotene or beta-cryptoxanthin resulted in a retinal formation of 29 and 55% of the amount formed from beta-carotene. Addition of 9 micrograms of lutein to an incubation with 3 micrograms beta-carotene reduced retinal formation, while lycopene had no effect. In conclusion, the beta-carotene cleavage assay with S-9 as enzyme source described in this report, seems a useful tool to study (dietary) determinants of beta-carotene cleavage activity, but for other purposes adaptation of the method is required.

Previous studies have indicated that consumption of boiled coffee raises total and low density lipoprotein (LDL) cholesterol, whereas drip-filtered coffee does not. We have tested the effect on serum lipids of consumed coffee that was first boiled and then filtered through commercial paper coffee filters. Sixty-four healthy volunteers consumed six cups per day of this boiled and filtered coffee for 17 days. Then, they were randomly divided into three groups, which, for the next 79 days, received either unfiltered boiled coffee (lipid content, 1.0 g/l), boiled and filtered coffee (0.02 g lipid/l), or no coffee. Serum total cholesterol levels rose by 0.42 mmol/l (16 mg/dl; 95% confidence interval [CI], 0.14-0.71), LDL cholesterol levels by 0.41 mmol/l (16 mg/dl; 95% CI, 0.16-0.66), and apolipoprotein B levels by 8.6 mg/dl (95% CI, 3.8-13.4) in those who consumed boiled coffee relative to those who consumed boiled and filtered coffee. Responses of triglycerides, high density lipoprotein cholesterol, and apolipoprotein A-I did not differ significantly among these groups. No significant effects on serum lipid levels were found in the boiled and filtered coffee-consuming group compared with those who drank no coffee. In subjects who drank boiled coffee, serum campesterol level, an indicator of cholesterol absorption, remained constant. The serum lathosterol level, an indicator of cholesterol synthesis, increased by 11% (p less than 0.05), but the lathosterol to cholesterol ratio did not change. We propose that paper filters of the type used for drip-filtered coffee retain the lipid present in boiled coffee and in that way remove the hypercholesterolemic factor.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolated vacuoles from ajmalicine-producing cell suspensions of Catharanthus roseus accumulated the alkaloid ajmalicine. Dissipation of the transtonoplast pH gradient with nigericin abolished ajmalicine accumulation, whereas dissipation of the transtonoplast potential with valinomycin had no effect. Addition of Mg-ATP resulted in a higher ajmalicine accumulation. Serpentine produced by the cells was largely recovered in isolated vacuoles; in contrast, ajmalicine was lost. Ajmalicine was converted in vitro into serpentine by horseradish basic peroxidases (EC 1.11.1.7). In cultured cells there was a striking conformity between the time course of serpentine content and that of the activity of basic peroxidases. Ajmalicine was converted efficiently into serpentine by basic peroxidases extracted from vacuoles and by intact isolated vacuoles. The results are consistent with the hypothesis that ajmalicine accumulates by an ion-trap mechanism and that the accumulated ajmalicine is converted into serpentine inside the vacuoles. By the transformation of ajmalicine into the charged serpentine a trap is created to retain the alkaloids more efficiently in the vacuole.

Cultured tobacco-pith tissue contains a cytoplasmic receptor for indoleacetic acid (IAA). The concentration of binding sites is very low in comparison to that of several auxin receptors found by other investigators. A few obvious possible causes (degradation or inactivation) were investigated. From the results we conclude that the low number of binding sites is real. The receptor binds IAA optimally at pH 7.5-7.8 and at a temperature of 24-30°C, when incubated for 25-30 min. The binding is very specific, as is shown by competition experiments. The concentration of the receptor in the callus tissue changes dramatically during each culture period, which suggests a possible role in development. The receptor was partly purified by gel filtration on Sepharose 6B followed by ion-exchange chromatography on DEAE-cellulose.