bluuebunny/crossref_metadata_2025 huggingface dataset:
Micelle formation in mixtures of nonionic and anionic detergents
Authors: Schick M. J. , Manning D. J.
Published: June 2007

This paper describes the effect of a homologous series of polyoxyethylene n‐dodecanols on the critical micelle concentration (CMC) of sodium n‐dodecyl alcohol sulfate as a function of composition of the mixtures and temperature. The CMC of the nonionic component of the mixed micelles is about one‐hundredth of that of the anionic. Only a gradual increase in the CMC values of the mixed micelles above the values of the nonionic components was observed in the composition range of 0舑90 mole % anionic detergent. This is followed by an abrupt transition to the high CMC values of the anionic component. The gradual increase of the CMC values in the range below 90 mole % anionic detergent of n‐dodecanol+ 4 EO exceeds that of the higher homologs containing 7, 23 and 30 ethylene oxide units. It is postulated that the degree of ionic repulsion of the ionic component in mixed micelles is markedly decreased as the proportion of nonionic component reaches a threshold range of 10 mole %. This effect is more pronounced with large ethylene oxide coils operating at the periphery of the micelle core than with short ethylene oxide coils. Thermodynamic data have been included.
Carbonyls in oxidizing fat. VIII. Effect of the Pool and Klose method on monocarbonyl precursors in autoxidized lard
Authors: Gaddis A. M. , Ellis R. , Currie G. T.
Published: June 2007

Monocarbonyl compounds isolated by the Pool and Klose method greatly exceeded those obtained by a mild quantitative vacuum distillation method. As indicated by amounts of individual aldehydes, the Pool and Klose method of reaction with 2,4‐dinitrophenylhydrazine on hydrated alumina partially decomposed hydroperoxides of unsaturated fatty acid glycerides and appeared to shift the normal balance of isomeric hydroperoxides. High proportions of unsaturated aldehydes were separated, and a new, highly unsaturated class in substantial amounts was present. Evidence, based on yield and type of aldehyde, suggests that in polyunsaturated fatty acids the hydroperoxide may preferentially form at the appropriate carbon furthest removed from the carboxyl group in the pentadiene system. This might partially explain the low proportions of alk‐2,4‐dienals in the free aldehydes of lard oxidized under mild conditions.
Fermentation of long chain compounds byTorulopsis magnoliae III. Preparation of dicarboxylic acids from hydroxy fatty acid sophorosides
Authors: Tulloch A. P. , Spencer J. F. T.
Published: June 2007

Conversion of hydroxy fatty acids, prepared from the products of fermentation of long chain hydrocarbons or fatty acids withTorulopsis magnoliae, to dicarboxylic acids with 15 to 18 carbon atoms is described. Both nitric acid oxidation and fission in 85% KOH give yields of 60舑75%, but the products have different compositions. The nature of the compound fermented determines the composition of the hydroxy acids produced and hence that of the derived dicarboxylic acids. A convenient method is presented for hydrolysis of the hydroxy fatty acid sophorosides obtained by fermentation.
Oxypropylation of fatty alcohols, and the sulfation products
Authors: Weil J. K. , Stirton A. J. , Barr Elizabeth A.
Published: June 2007

Reaction of propylene oxide, rather than ethylene oxide, with fatty alcohols, gives a higher yield (50%) of mono‐oxyalkylation product because the secondary alcohol formed is less reactive than the primary alcohol formed with ethylene oxide. Rate of further reaction is about half the rate of the parent primary alcohol. Distributuon of propylene oxide reaction products follows the Weibull‐Nycander equation.

Analysis of reaction products was accomplished by gas‐liquid chromatography of the acetylated ether alcohol mixtures. Pure mono‐oxypropylated alcohols ROCH2CHOHCH3 and in some cases dioxypropylated alcohols R[OCH2CH(CH3)]2OH were separated by fractional distillation.

Individual ether alcohols and products with a known average number of oxypropyl groups were sulfated and evaluated in terms of Krafft point, critical micelle concentration, detergency, foam height and lime soap dispersing properties. Incorporation of one oxypropyl group was more effective than the same degree of oxyethylation, and improved solubility with no significant loss in foaming and detergency. Ether alcohol sulfates from propylene oxide are stable to alkaline hydrolysis and nearly equal to the sulfates from ethylene oxide in their stability to acid hydrolysis.
The accuracy of ester fractionation analysis of butterfat
Authors: Hansen R. P.
Published: June 2007

The ester fractionation method under the conditions described, has been shown to yield for triplicate fatty acid analyses of three different butterfat samples, results which are reproducible within an over‐all standard deviation of ±0.26.

Statistical interpretation of the differences between fatty acid analyses of two samples shows that the method used in this work is sufficiently accurate to detect seasonal variations in butterfat.
Buckwheat leaf meal fat. I. Its physical and chemical characteristics and the constituents of the water‐soluble and unsaponifiable fractions of the saponified fat
Authors: Krewson Charles F. , Couch James F.
Published: June 2007

The leaf meal fat of the Japanese buckwheat plant has been prepared, and its physical and chemical characteristics have been determined. Spectrophotometric analysis of the fat of this variety indicates that in composition it is similar to the fat of the Tartary variety, the one now preferably used for manufacture of rutin. The large quantity of unsaponifiable matter is unusual. This fraction contains carotene, xanthophylls, phytol, β‐sitosterol, and an eicosanol.

Also of interest is the presence in the fat of significant quantities of lecithin when isopropanol is used for extraction. The water‐soluble acidic constituents of the saponified fat consist of the organic acids formic, acetic, and lactic, and the inorganic acids phosphoric, nitric, sulfuric, and hydrochloric. Ammonia was present in the alcohol distillate collected after saponification, and glycerol was identified in the water‐soluble acid fraction. Quantitative values are given for formic and lactic acids and for ammonia.
The comparative nutritive value of mono‐, Di‐, and triglycerides
Authors: Mattson F. H. , Baur F. J. , Beck L. W.
Published: June 2007

Weanling rats were fed diets containing various pure mono‐, di‐, or triglycerides at a 25% level for 10 weeks. The following results were obtained:

Mono‐, di‐, and triglycerides of corresponding fatty acid composition were of equivalent caloric efficiency.

The caloric efficiencies of the mono‐ and triglycerides of pure lauric or stearic acid were found to be low. This may have been due wholly or partially to poor absorption.

Autopsies and histological examination of the tissues of the animals revealed no abnormalities attributable to the consumption of any of these fats. Appearance of all animals was normal throughout the experiment.

The body fat of the animals was the same regardless of the type of glyceride structure fed. However the type of body fat deposited reflected, in part, the fatty acid component of the dietary glyceride.

From these results it is concluded that, except for differences in caloric value, mono‐, di‐, and triglycerides of corresponding fatty acid composition, are nutritionally equivalent.
Pilot extraction studies. Evaluation of defatted yeast and yeast fat
Authors: Brasch J. F.
Published: June 2007

Conclusions

The pilot studies performed on the extraction of fat from yeast indicate that it is possible commercially to extract yeast to .05% residual fat or less, using finely pulverized yeast in a continuous countercurrent horizontal extractor and Skellysolve B for the solvent.

The yeast obtained by this extraction is lighter in color and, when fresh, has a blander taste than similar unextracted yeast, provided that it is dried under carefully controlled conditions so that all the solvent is removed and yet the yeast is not toasted. However after several months' aging, the extracted yeast does not compare favorably with fresh unextracted yeast on a taste basis.

The fat extracted has a high phosphatide and high unsaponifiable fraction and will vary considerably in composition, depending on species of yeast, environment during growth, and method of extraction. Because of its composition it cannot be conveniently refined and therefore would not compete favorably with vegetable oils for bulk industrial use.
Note on the linoleic acid‐tocopherol relationship in fats and oils
Authors: Hove Edwin L. , Harris Philip L.
Published: June 2007

Conclusions

The linoleic acid and total tocopherol content of animal and vegetable oils, for which these characteristics are known, are correlated with a high degree of significance;r=+0.79.
A note on some physical properties of the animal tallows and their glyceride composition
Authors: Kartha A. R. S.
Published: June 2007

The results of Bailey on the alterations produced by interesterification in the melting points and micropenetration values at 70°F. to 90°F. of various animal tallows cannot be explained on the basis of the
Production of polyvinyl esters by ester interchange
Authors: Eckey E. W. , Alderson R. O. , Woestman R. J.
Published: June 2007

Mixed polyvinyl esters of acetic acid and higher fatty acids can be made by ester interchange between polyvinyl acetate and fatty esters. Their properties indicate that some of these products merit attention as materials for use in the drying oil industries. Because of their enhanced drying qualities and greater tolerance of the presence of saturated acid components, in comparison with the corresponding glycerides, they potentially broaden the range of fatty materials utilizable as drying oils.
2‐Monoglycerides
Authors: Brokaw G. Y. , Perry E. S. , Lyman W. C.
Published: June 2007

Commerical monoglycerides and mono‐diglycerides contain 2‐isomers. The amount is in the range of 5 to 8% of the total monoglyceride content.

2‐Mono‐olein and 2‐monostearin have been isolated from the reaction products of glycerin with oleic and with stearic acids.

At least for cake baking utility, 2‐monoglycerides appear to be equivalent to 1‐monoglycerides.

An analysis for total monoglyceride content is proposed. It incorporates perchloric acid isomerization directly into the usual periodic acid analusis.
Physical characterization of a) a series of ethyl esters and b) a series of ethanoate esters
Authors: Shigley J. W. , Bonhorst C. W. , Liang P. M. , Althouse P. M. , Triebold H. O.
Published: June 2007

Physical characterizations of (1) the ethyl esters of the naturally occurring C6−C18 saturated fat acids and (2) the ethanoate esters of the saturated alcohols corresponding to the above acids have been made. They are a) refractive indices at 20°, 25°, 30°, 35°, and 40°C., b) densities and viscosities at 35°, 50°, 65°, 80°, and 95° C., and c) boiling points at several pressures.

The physical characteristics exhibited by the two series of esters are quite similar. However the actual values obtained for the ethanoate esters are slightly higher than those obtained for the corresponding ethyl esters.
Phase studies of the systems synthetic soap‐sodium chloride‐water
Authors: Blokker P. C.
Published: June 2007

The phase behavior of ternary mixtures of various synthetic soaps, sodium chloride, and water are described. Several mixed sodium alkyl sulphates were investigated in detail at two temperatures; pure alkyl sulphates and alkyl and alkylarene sulphonates were investigated only tentatively. The phase relations showed a striking resemblance with those of fatty acid soaps.
Urea adducts of mono‐ and diesters of fatty acids
Authors: Heckles J. S. , Dunlap L. H.
Published: June 2007

The experimental work has shown how molecular configurations of fatty acid glycerides affect urea complex formation. Extraction data indicate that urea will form a complex with glycerol monopalmitate, monostearate, and mono‐oleate but not under these conditions with glycerol monolinoleate or monolinolenate from mixtures containing these monoesters. Data also indicate that it is easier for urea to form a complex with monoglycerides than with diglycerides.

In a mixture containing mono‐ and diglycerides of saturated and unsaturated fatty acids, urea will separate first on the basis of saturation, then secondly on the basis of the degree of esterification of the glycerol.
Laparoscopic Intragastric Full‐thickness Excision (LIFE) of Posterior Gastric Lesions under Flexible Endoscopic Control—A Feasibility Study
Authors: Hoya Yoshiyuki , Yamashita Makoto , Inagaki Takuya , Yanaga Katsuhiko
Published: June 2007

Background

We have developed a new technique for treatment of intramucosal carcinoma

which exceeds the standard indication for endoscopic mucosal resection and carcinoma invading the submucosa without lymph node metastasis that are located in the posterior wall of the stomach, which we refer to as laparoscopic intragastric full‐thickness excision (LIFE) under flexible endoscopic control.

Surgical Technique

Three pigs were used for the study. Three trocars were used. The first trocar (trocar # 1) was placed in the subumbilical region to introduce the videoscope, whereas the second and third trocars (trocar # 2 and trocar # 3) were punctured percutaneously into the abdominal cavity. A straight needle with 3‐0 silk suture was attached to a T‐bar on the wire side and inserted into the abdominal cavity. An area adjacent to the lesion in the posterior wall of the stomach was pierced by the straight needle, which was then pulled into the stomach using the forceps of the endoscope. The T‐bar, after being passed through the abdominal wall, was fixed outside the gastric wall, and trocar # 3 was repositioned in the stomach by the percutaneous transgastric route. The posterior wall of the stomach was pulled inward by the T‐bar, and the lesion was removed by several excisions with laparoscopic stapling devices inserted through trocar # 3; extraction of the specimen was achieved through trocar # 3. The gastrotomy site was suture‐closed using instruments positioned through trocar # 2 and trocar # 3 under laparoscopy.

Conclusions

Based on a feasibility study in pigs, the LIFE procedure can be performed for lesions of the posterior wall of the stomach.
Advanced glycation end products and the absence of premature atherosclerosis in glycogen storage disease Ia
Authors: den Hollander N. C. , Mulder D. J. , Graaff R. , Thorpe S. R. , Baynes J. W. , Smit G. P. A. , Smit A. J.
Published: June 2007

Introduction

Despite their unfavourable cardiovascular risk profile, patients with glycogen storage disease type Ia (GSD Ia) do not develop premature atherosclerosis. We hypothesized that this paradox might be related to a decreased formation of advanced glycation end products (AGEs) resulting from lifetime low plasma glucose levels and decreased oxidative stress.

Methods

In 8 GSD Ia patients (age 20–24 years) and 30 matched controls we measured carotid intima‐media thickness (IMT), skin autofluorescence (AF; a non‐invasive index for AGEs), and specific AGEs (pentosidine, N‐(carboxymethyl)lysine (CML), N‐(carboxyethyl)lysine (CEL)) and collagen linked fluorescence (CLF, measured at excitation/emission wavelength combinations of 328/378 and 370/440 nm) in skin samples.

Results

Carotid IMT was significantly lower in GSD Ia patients. Skin AF did not differ between patients and controls. The skin samples showed higher CEL levels in the patient group (p=0.008), but similar levels of pentosidine, CML, and CLF. In the total group, skin AF correlated with CML (r=0.39, p=0.031), CLF 328/378 nm (r=0.53; p=0.002) and CLF 370/440 nm (r=0.60; p=0.001). In the control group, AF also correlated with the maximum carotid IMT (r=0.6; p=0.004).

Conclusion

Although our data confirm that GSD Ia patients present with a reduced burden of atherosclerosis, this phenomenon cannot be explained by differences in AGE accumulation as measured in the skin.
Introgressive hybridization as the breakdown of postzygotic isolation: a theoretical perspective
Authors: Tanaka Yoshinari
Published: June 2007

In this paper, both the empirical and theoretical genetic aspects of human‐mediated introgressive hybridization are reviewed in terms of their association with the breakdown of postzygotic isolating mechanisms. I also compare several simulation models with an ecological or genetic focus that are relevant to the prediction and risk assessment of genetic extinction due to hybridization. One barrier to devising comprehensive risk assessment frameworks is a lack of sufficient population genetic studies that associate introgressive hybridization with specific isolating mechanisms. A gametic model based on multilocus underdominant fitness is one of the best genetic models for introgressive hybridization because it explicitly incorporates the postzygotic isolating mechanism known as Dobzhansky–Muller genetic incompatibility.
Descriptive Social Norms as Underappreciated Sources of Social Control
Authors: Cialdini Robert B.
Published: June 2007

Böckenholt and van der Heijden’s results regarding compliance with insurance regulations—that the enforcement activities of a regulatory agency were relatively unpredictive of compliance—are consistent with findings from other domains (e.g., tax adherence), where personal factors and informal social controls have been shown to play a more significant role. However, the specific form of informal social control investigated in Böckenholt and van der Heijden’s study (the perceived approval/disapproval of friends and family) is not the only kind of informal social control that has proven effective in spurring compliance. Descriptive social norms, which involve perceptions not of what others approve but of what others actually do, also influence compliance decisions powerfully. Yet, the role of descriptive social norms in rule adherence is often underappreciated by governed and governors alike. The consequences of this relative lack of recognition are discussed within the arena of compliance with pro-environmental regulations and requests.
Lung function with carvedilol and bisoprolol in chronic heart failure: Is β selectivity relevant?
Authors: Agostoni Piergiuseppe , Contini Mauro , Cattadori Gaia , Apostolo Anna , Sciomer Susanna , Bussotti Maurizio , Palermo Pietro , Fiorentini Cesare
Published: June 2007

Background

Carvedilol is a β‐blocker with similar affinity for β1‐ and β2 receptors, while bisoprolol has higher β1 affinity. The respiratory system is characterized by β2‐receptor prevalence. Airway β receptors regulate bronchial tone and alveolar β receptors regulate alveolar fluid re‐absorption which influences gas diffusion.

Aims

To compare the effects of carvedilol and bisoprolol on lung function in patients with chronic heart failure (CHF).

Methods and results

We performed a double‐blind, cross‐over study in 53 CHF patients. After 2 months of full dose treatment with either carvedilol or bisoprolol, we assessed lung function by salbutamol challenge, carbon monoxide lung diffusion (DLCO), including membrane conductance (DM), and gas exchange during exercise. FEV1 and FVC were similar; after salbutamol FEV1 was higher with bisoprolol (p<0.04). DLCO was 82±21% of predicted with carvedilol and 90±20% with bisoprolol (p<0.01) due to DM changes. Peak VO2 was 17.8±4.5 mL/min/kg on bisoprolol and 17.0±4.6 on carvedilol, (p<0.05) with no differences in bronchial tone (same expiratory time) throughout exercise. Differences were greater in the 22 subjects with DLCO<80%.

Conclusion

Carvedilol and bisoprolol have different effects on DLCO and response to salbutamol. DLCO differences, being DM related, are due to changes in active membrane transport which is under alveolar β2‐receptor control. Peak VO2 was slightly higher with bisoprolol particularly in CHF patients with reduced DLCO.
The impact of low back pain on work: A study in primary care consulters
Authors: Wynne‐Jones Gwenllian , Dunn Kate M. , Main Chris J.
Published: June 2007

Background: The cost of low back pain (LBP) to employers is high, with an estimated £9090 million lost in the United Kingdom in 1998. Economic analysis of LBP has focused on work absence among the employed. There is little research characterising individuals who report reduced duties or who are not in employment because of LBP.

Aims: To compare the health related characteristics of primary care LBP consulters reporting usual employment, reduced duties, sick leave and non‐employment as a result of LBP.

Methods: Prospective cohort study recruiting LBP consulters aged 30–59 years of age from five general practices in North Staffordshire.

Results: Nine hundred and thirty‐five participants completed the baseline phase, 65% were in employment and 35% were not in employment. Of the employed participants over 1 in 10 (11%) were undertaking reduced duties and almost one‐fifth were reporting sick leave (22%). Furthermore, 37% of non‐employed consulters reported that LBP was the reason for non‐employment. Significant differences at baseline in socioeconomic status, self‐rated health, anxiety, depression and disability were found between those undertaking their usual job, those on reduced duties and those on sickness absence due to LBP, with those participants further removed from the work force reporting worse health across all measures. Significant differences were also found in self‐rated health between those not working due to LBP and those not working for other reasons, with participants not working due to LBP reporting worse self‐rated health. At follow‐up, work status was found to be relatively stable.

Conclusion: These findings indicate that the economic impact of LBP may be higher than previously estimated when data on reduced duties is combined with work absence. The additional impact of unemployment due to LBP should also be included in future assessments of the impact of LBP on the workforce.
ELOVL2 overexpression enhances triacylglycerol synthesis in 3T3‐L1 and F442A cells
Authors: Kobayashi Tsutomu , Zadravec Damir , Jacobsson Anders
Published: June 2007

Elongation of very long‐chain fatty acids (ELOVL) members were overexpressed in two preadipocyte cell lines, ELOVL2 and ELOVL3 in 3T3‐L1 cells, and ELOVL1–3 in F442A cells. Cells overexpressing ELOVL2, whose preferred substrates are arachidonic acid (AA, C20:4n−6) and eicosapentaenoic acid (EPA, C20:5n−3), showed an enhanced triacylglycerol (TAG) synthesis and subsequent accumulation of lipid droplets. Incorporation of fatty acid (FA) but not of glucose into TAG was enhanced by ELOVL2‐overexpression. Two lipogenic genes encoding diacylglycerol acyltransferase‐2 (DGAT2) and fatty acid‐binding protein‐4 (FABP4, aP2) were induced in ELOVL2‐overexpressing cells, whereas no such effect was seen on the fatty acid synthase (FAS) gene.
Severe abdominal dog bite wounds in a pregnant cat
Authors: Kumru Ismail H. , Seyrek-Intas Kamil , Tuna Bilginer , Celimli Nureddin , Seyrek-Intas Deniz
Published: June 2007

Bite wounds are one of the most common reasons for admission of cats to veterinary clinics. Appropriate wound management seems to be more important in the successful outcome of bite wound injuries than antibiotic therapy alone. This report describes a heavily pregnant cat that suffered severe abdominal bite wounds necessitating treatment with extensive surgery. A necrotic herniated kidney, abdominal wall hernias, internal peritoneal ruptures and fracture of the thirteenth rib, gravid cornu rupture, an extrauterine dead foetus and its free kidney were all observed at laparotomy. At surgery the extrauterine dead foetus was removed, and two live foetuses were retrieved by en bloc ovariohysterectomy. A right nephrectomy and partial costectomy were also performed. Two weeks postoperatively, the cat had fully recovered without a problem. Bite wounds encountered in cats, though severe and invasive, can be tolerated and extensive surgical management can result in successful outcomes even under suboptimal conditions.
Lagrangian conditional statistics, acceleration and local relative motion in numerically simulated isotropic turbulence
Authors: YEUNG P. K. , POPE S. B. , KURTH E. A. , LAMORGESE A. G.
Published: June 2007

Lagrangian statistics of fluid-particle velocity and acceleration conditioned on fluctuations of dissipation, enstrophy and pseudo-dissipation representing different characteristics of local relative motion are extracted from a direct numerical simulation database of stationary (forced) homogeneous isotropic turbulence. The grid resolution in the simulations is up to 20483, and the Taylor-scale Reynolds number ranges from about 40 to 650, where characteristics of small-scale intermittency in the Eulerian flow field are well developed. A key joint statistic of the conditioning variables is the dissipation-enstrophy cross-correlation, which is asymmetric, but becomes less so at high Reynolds number. Conditional velocity autocorrelations are consistent with rapid changes in the velocity of fluid particles moving in regions of large velocity gradients. Examination of statistics conditioned upon enstrophy, especially in a local coordinate frame moving with the vorticity vector, and of the centripetal acceleration suggests the presence of vortex-trapping effects which persist for several Kolmogorov time scales. Further results on acceleration statistics and joint velocity-acceleration autocorrelations are also presented to help characterize in detail the properties of a joint stochastic process of velocity, acceleration and the pseudo-dissipation. Together with recent work on Eulerian conditional acceleration and Reynolds-number dependence of basic Lagrangian quantities, the present results are directly useful for the development of a new stochastic model formulated to account for intermittency and Reynolds-number effects as described in detail in a companion paper.
Diet selection and animal state: an integrative framework
Authors: Kyriazakis Ilias , Tolkamp Bert J. , Emmans Gerry
Published: June 2007

In the present paper we deal with the problems of explaining and predicting diet selection of animals under controlled conditions, i.e. conditions that can be described and in which any influences of the environment can be either controlled or at least monitored. Diet selection is considered within an integrative framework of feeding behaviour that views both food intake and diet selection as an outcome of the animal's internal state and knowledge of the feeding environment. Three questions that arise from the framework are considered: (1) how do animals learn about foods available to them as a choice? (2) what changes in internal state affect diet selection? (3) how much time is needed for a change in the animal's internal state to be detected and for it to react to this change through a modification of its diet selection? It is proposed that animals have developed behavioural mechanisms that allow them to recognize foods on the basis of their nutritional as well as other properties. The rate at which animals learn about foods depends largely on the extent of the animal's deficiency and on the extent of the post-ingestive consequences induced by the foods. There is little evidence that animals modify their diet selection in response to short-term systemic fluctuation of their internal environment. On the other hand, long-term changes in the internal state of the animal lead to consequent long-term changes in diet selection. The time needed for a change in diet selection to be observed depends on the deviation created in the animal's internal state, either as a result of a physiological change or as a consequence of feeding. Thus, a more appropriate question to consider is not 'what time period matters to the animal?' but 'how much change or deviation in the internal state is the animal prepared to accept?'
High-fat and low-fat (behavioural) phenotypes: biology or environment?
Authors: Blundell John E. , Cooling John
Published: June 2007

It is now widely accepted that obesity develops by way of genetic mechanisms conferring specific dispositions which interact with strong environmental pressures. It is also accepted that certain dispositions constitute metabolic risk factors for weight gain. It is less well accepted that certain patterns of behaviour (arising from biological demands or environmental influences) put individuals at risk of developing a positive energy balance and weight gain (behavioural risk factors). Relevant patterns of behaviour include long-lasting habits for selecting and eating particular types of foods. Such habits define two distinct groups characterized as high-fat (HF) and low-fat (LF) phenotypes. These habits are important because of the attention given to dietary macronutrients in body-weight gain and the worldwide epidemic of obesity. Considerable evidence indicates that the total amount of dietary fat consumed remains the most potent food-related risk factor for weight gain. However, although habitual intake of a high-fat diet is a behavioural risk factor for obesity, it does not constitute a biological inevitability. A habitual low-fat diet does seem to protect against the development of obesity, but a high-fat diet does not guarantee that an individual will be obese. Although obesity is much more prevalent among HF than LF, some HF are lean with BMI well within the normal range. The concept of 'different routes to obesity' through a variety of nutritional scenarios can be envisaged, with predisposed individuals varying in their susceptibility to different dietary inputs. In a particular subgroup of individuals (young adult males) HF and LF displayed quite different profiles of appetite control, response to nutrient challenges and physiological measures, including BMR, RQ, heart rate, plasma leptin levels and thermogenic responses to fat and carbohydrate meals. These striking differences suggest that HF and LF can be used as a conceptual tool to investigate the relationship between biology and the environment (diet) in the control of body weight.
Assuaging nutritional complexity: a geometrical approach
Authors: Simpson Stephen J. , Raubenheimer David
Published: June 2007

We have introduced a framework that enables the identification of the important elements in complex nutritional systems, and the quantification of the interactions among them. These interactions include those among the multiple constituents of the ingesta, as well as between behavioural (ingestive) and physiological (post-ingestive) components of nutritional homeostasis. The resulting descriptions provide a powerful means to generate and test hypotheses concerning the mechanisms, ecology and evolution of nutritional systems. We provide an overview of the key concepts involved in our scheme, and then introduce four examples in which the framework is used to develop and test hypotheses. In the first example we use comparative methods based on a data set of 117 insect species to test a prediction about the relationship between evolving an association with bacterial endosymbionts and the composition of the optimal diet. Second, using two species of locusts (a grass specialist and a generalist), we consider the relationship between an animal's diet breadth and the decision rules employed when feeding on foods containing suboptimal protein: carbohydrate values. Third, we introduce a mathematical model that predicts the dose-response properties of gustatory systems in the context of nutritional homeostasis. Finally, we consider the interaction between tannic acid and macronutrient balance in the diet of locusts.
Effects of extreme environments on food intake in human subjects
Authors: Westerterp-Plantenga Margriet S.
Published: June 2007

Effects of extreme environments on food intake in human subjects are analysed as behavioural and physiological adaptations to annual and circadian rhythms, temperature and altitude. Effects of the environment on food intake through food availability have direct consequences on energy balance and body weight. Different geographical regions show variations in the composition of dietary foods, i.e. the relative proportions of carbohydrate, protein and fat. In developing countries the annual cycle appears to affect body weight through dependence on food availability. In West-European countries this effect appears to depend on physical activity. Energy and macronutrient intakes appear to follow a circadian pattern, with breakfast being relatively high in carbohydrate and dinner being relatively high in fat. In cold conditions, maintaining an adequate food intake is important in sustaining normal physiological responses to cold. Evidence for a possible cold-induced increase in appetite is poor. A condition influencing level of intake is the palatability of the food. High altitude, i.e. hypobaric hypoxia, appears to reduce appetite, energy intake and body mass, irrespective of acute mountain sickness (AMS). Meal size is reduced and meal frequency increased. Under circumstances of AMS, dissociation between appetite and hunger occurs. Thus, spontaneous adaptation to extreme environments requiring increased energy intake occurs first by adaptation of body weight to a new energy balance. In general, prevention of a negative energy balance occurs by learning with respect to food intake. After return to normal, adjustment of energy intake to the original energy balance occurs with restoration of body weight.
Habitat selection according to the ability of animals to eat, digest and detoxify foods
Authors: Duncan Alan J. , Gordon Iain J.
Published: June 2007

Large herbivores play a major role in shaping vegetation community dynamics through selective consumption of particular plants and plant communities. An understanding of the factors influencing diet selection at the level of individual bites (‘bite scale’) is important for prediction of the impact of herbivores on vegetation at the habitat scale. Bite-scale diet selection represents an integration of the twin goals of maximizing nutrient intake and minimizing toxin intake. Recent research with ruminants in pen-fed situations has shown that animals are able to make choices between artificial foods that maximize growth and other production variables. The role of post-ingestive feedback as an important mechanism for allowing animals to assess the nutritional quality of particular foods, and so select optimal diets, has been recognized in a number of recent experiments. Our understanding of the role of toxin intake minimization in diet selection decisions is more rudimentary. An important advance in the last decade has been the acknowledgement of the role of post-ingestive feedback and learning as a mechanism for avoidance of dietary toxicity. Further research is required to assess the importance of these processes in relation to free-grazing animals. The extent to which an understanding of bite-scale diet selection can be used to predict habitat utilization is not well understood. At the habitat scale additional factors such as predator avoidance, social constraints, avoidance of parasitism and microclimatic effects have an important influence on foraging decisions. Future research needs to focus on developing a quantitative understanding of such decisions at the habitat scale.
Social determinants of food choice
Authors: Shepherd Richard
Published: June 2007

Food choice is influenced by a large number of factors, including social and cultural factors. One method for trying to understand the impact of these factors is through the study of attitudes. Research is described which utilizes social psychological attitude models of attitude-behaviour relationships, in particular the Theory of Planned Behaviour. This approach has shown good prediction of behaviour, but there are a number of possible extensions to this basic model which might improve its utility. One such extension is the inclusion of measures of moral concern, which have been found to be important both for the choice of genetically-modified foods and also for foods to be eaten by others. It has been found to be difficult to effect dietary change, and there are a number of insights from social psychology which might address this difficulty. One is the phenomenon of optimistic bias, where individuals believe themselves to be at less risk from various hazards than the average person. This effect has been demonstrated for nutritional risks, and this might lead individuals to take less note of health education messages. Another concern is that individuals do not always have clear-cut attitudes, but rather can be ambivalent about food and about healthy eating. It is important, therefore, to have measures for this ambivalence, and an understanding of how it might impact on behaviour.
Pre-operative nutritional assessment
Authors: Corish Clare A.
Published: June 2007

Protein-energy undernutrition, or the possibility of its development, has been documented to occur frequently in surgical patients admitted to hospital. Nutritional status is known to deteriorate over the course of the hospital stay, with poor awareness by medical and nursing staff as to the deleterious effects of impaired nutritional status on clinical outcome and hospital costs. While there is no consensus on the best method for assessment of the nutritional status of surgical patients pre-operatively, there are a number of techniques available. These techniques can be divided into two types, those suitable for screening for nutrition risk on admission to hospital and those used to fully assess nutritional status. Both techniques have their limitations, but if used correctly, and their limitations recognized, should identify the appropriate degree of nutritional intervention for an individual patient in a timely and cost-effective manner. The techniques currently available for nutritional screening and nutritional assessment are reviewed, and their applicability to the Irish setting are discussed in the present paper.
Observation of intramyocellular lipids by means of1H magnetic resonance spectroscopy
Authors: Boesch Chris , Décombaz Jacques , Slotboom Johannes , Kreis Roland
Published: June 2007

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are being increasingly used for investigations of human muscle physiology. While MRI reveals the morphology of muscles in great detail (e.g. for the determination of muscle volumes), MRS provides information on the chemical composition of the tissue. Depending on the observed nucleus, MRS allows the monitoring of high-energy phosphates (31P MRS), glycogen (13C MRS), or intramyocellular lipids (1H MRS), to give only a few examples. The observation of intramyocellular lipids (IMCL) by means of1H MRS is non-invasive and, therefore, can be repeated many times and with a high temporal resolution. MRS has the potential to replace the biopsy for the monitoring of IMCL levels; however, the biopsy still has the advantage that other methods such as those used in molecular biology can be applied to the sample. The present study describes variations in the IMCL levels (expressed in mmol/kg wet weight and ml/100 ml) in three different muscles before and after (0, 1, 2, and 5 d) marathon runs for a well-trained individual who followed two different recovery protocols varying mainly in the diet. It was shown that the repletion of IMCL levels is strongly dependent on the diet post exercise. The monitoring of IMCL levels by means of1H MRS is extremely promising, but several methodological limitations and pitfalls need to be considered, and these are addressed in the present review.
Macronutrient metabolism of adipose tissue at rest and during exercise: a methodological viewpoint
Authors: Frayn Keith N.
Published: June 2007

The metabolism of white adipose tissue is regulated by many factors, including hormones and substrates delivered in the blood, the activity of the autonomic nervous system and the rate of flow of blood through the tissue. An integrated view of adipose tissue metabolism can only be gained, therefore, from studiesin vivo. Of the various techniques available for studying adipose tissue metabolismin vivo, the measurement of arterio-venous differences offers some unique possibilities. In human subjects this technique has been performed mostly by catheterization of the venous drainage of the subcutaneous abdominal depot. Studies using this technique indicate that adipose tissue has an active pattern of metabolism, responding rapidly to meal ingestion by suppressing the release of non-esterified fatty acids, or to exercise with an increase in fat mobilization. Adipose tissue blood flow may also change rapidly in these situations; for instance, it increases markedly after a meal, potentially increasing the delivery of triacylglycerol to the enzyme lipoprotein lipase (EC3.1.1.34) for hydrolysis. During exercise, there is evidence that adipose tissue blood flow does not increase sufficiently to allow delivery of all the fatty acids released into the systemic circulation. The various adipose tissue depots have their own characteristic metabolic properties, although in human subjects these are difficult to study with the arterio-venous difference technique. A combination of tracer infusion with selective catheterization allows measurements of leg, splanchnic and non-splanchnic upper-body fat mobilization and triacylglycerol clearance. Development of such techniques may open up new possibilities in the future for obtaining an integrated picture of adipose tissue function and its depot-specific variations.
Microdialysis: use in human exercise studies
Authors: Arner Peter
Published: June 2007

Microdialysis has been used for 25 years to study brain function in vivo. Recently, it has been developed for investigations on peripheral tissues. A microdialysis catheter is an artificial blood vessel system which can be placed in the extracellular space of various tissues such as adipose tissue and skeletal muscle in order to examine these tissues in situ. Molecules are collected from the tissue by the device and their true interstitial concentration can be estimated. Metabolically-active molecules can be delivered to the interstitial space through the microdialysis probe and their action on the tissue can be investigated locally without producing generalized effects. It is also possible to study local tissue blood flow with microdialysis by adding a flow marker (usually ethanol) to the microdialysis solvent. The microdialysis technique is particularly useful for studies of small and water-soluble molecules. A number of important observations on the in vivo regulation of lipolysis, carbohydrate metabolism and blood flow in human skeletal muscle and adipose tissue have been made recently using microdialysis.
Vasoactive substances in the interstitium of contracting skeletal muscle examined by microdialysis
Authors: Bangsbo J.
Published: June 2007

In the study of the regulation of skeletal muscle blood flow during exercise it is useful to obtain information regarding the concentrations of vasoactive substances in the muscle interstitium, a site where the compounds act on the vascular and skeletal muscle cells. The microdialysis technique is a useful tool for measuring interstitial substances in the muscle at rest and during exercise in human subjects, and the technique can also be used to study the effect of both systemic and local interventions in a specific area of an exercising muscle. Probe recovery, which represents the relative amount of a substance that is diffusing to the dialysis membrane, changes from rest to exercise and can be determined by the internal-standard technique which allows for a relatively high time resolution (min). Furthermore, the use of electrodes at the microdialysis outlet makes it possible to perform continuous measurements of interstitial substances. The present review gives examples of how the microdialysis technique has been applied to study potentially important vasodilators such as adenosine, NO and K+ in human skeletal muscles and highlights areas for future research to establish the functional importance of these compounds.
An introduction to the use of tracers in nutrition and metabolism
Authors: Rennie Michael J.
Published: June 2007

The present article is a review written at a level suitable for students and new workers to the field of techniques in common current use for the measurement of static and dynamic features of metabolism, especially nutritional metabolism. It covers the nature of radioactive and stable-isotope tracers, the means of measuring them, and the advantages and disadvantages of their use. The greater part of the review deals with methods for the measurement of pool sizes and metabolic processes, with the emphasis being on protein metabolism, a field the author knows best. The examples given are from a variety of sources, including the work of the author, but the principles underlying the techniques are universally applicable to all metabolic investigations using tracers.
Correction factors for 13C-labelled substrate oxidation at whole-body and muscle level
Authors: van Hall Gerrit
Published: June 2007

The oxidation of fatty acids, carbohydrates and amino acids can be measured by quantifying the rate of excretion of labelled CO2 following administration of 14C- or 13C-labelled substrates at whole-body and tissue level. However, there is a theoretical need to correct the oxidation rates for the proportion of labelled CO2 that is produced via oxidation but not excreted. Furthermore, depending on the substrate and position of the C label(s), there may also be a need to correct for labelled C from the metabolized substrate that does not appear as CO2, but rather becomes temporarily fixed in other metabolites. The bicarbonate correction factor is used to correct for the labelled CO2 not excreted. Recently, an acetate correction factor has been proposed for the simultaneous correction of CO2 not excreted and label fixed in other metabolites via isotopic exchange reactions, mainly in the tricarboxylic acid cycle. Changes in metabolic rate induced, for example, by feeding, hormonal changes and physical activity, as well as infusion time, have been shown to affect both correction factors. The present paper explains the theoretical and physiological basis of these correction factors and makes recommendations as to how these correction factors should be used in various physiological conditions.
Long-term renormalization of chromatic mechanisms following cataract surgery
Authors: DELAHUNT PETER B. , WEBSTER MICHAEL A. , MA LEI , WERNER JOHN S.
Published: June 2007

The optical density of the human crystalline lens progressively increases with age, the greatest increase in the visible spectrum being at short wavelengths. This produces a gradual shift in the spectral distribution of the light reaching the retina, yet color appearance remains relatively stable across the life span, implying that the visual system adapts to compensate for changes in spectral sensitivity. We explored properties of this adaptive renormalization by measuring changes in color appearance following cataract surgery. When the lens is removed, cataract patients often report a large perceptual shift in color appearance that can last for months. This change in color appearance was quantified for four cataract patients (63–84 years) by determining the chromaticity of stimuli that appeared achromatic before surgery, and at various intervals after surgery for up to 1 year. Stimuli were presented on a calibrated CRT as 9.5-deg spots, with 3-s duration and 3-s interstimulus intervals (ISIs). Chromaticity was adjusted by the subjects in CIE L*a*b* color space with luminance fixed at 32 cd/m2, on a dark background. We also estimated the optical density of the cataractous lens by comparing absolute scotopic thresholds from 410 nm to 600 nm before and after surgery. The results demonstrated that immediately following surgery there is a large increase in the short-wave light reaching the retina, mainly below 500 nm. The achromatic settings generally showed an initial large shift in the “yellow” direction after surgery that gradually (but never fully) returned to the original achromatic point before surgery. The shifts in the achromatic point occur over a number of months and appear to occur independently of the fellow eye.