Effects of Hofmeister salt series on gluten network formation: Part I. Cation series.

Different cationic salts were used to investigate the effects of the Hofmeister salt series on gluten network formation. The effects of cationic salts on wheat flour dough mixing properties, the rheological and the chemical properties of the gluten extracted from the dough with different respective salts, were investigated. The specific influence of different cationic salts on the gluten structure formation during dough mixing, compared to the sodium ion, were determined. The effects of different cations on dough and gluten of different flours mostly followed the Hofmeister series (NH4(+), K(+), Na(+), Mg(2+) and Ca(2+)). The impacts of cations on gluten structure and dough rheology at levels tested were relatively small. Therefore, the replacement of sodium from a technological standpoint is possible, particularly by monovalent cations such as NH4(+), or K(+). However the levels of replacement need to take into account sensory attributes of the cationic salts.

Effects of Hofmeister salt series on gluten network formation: Part II. Anion series.

Different anion salts from the Hofmeister series were used to investigate their effects on gluten network formation. The effects of these anion salts on the mixing properties of the dough and the rheological and chemical properties of gluten samples extracted from the dough with these respective salts were compared. The aim of this work was to determine how different anion salts influence the formation of the gluten structure during dough mixing. It was found that the Hofmeister anion salts affected the gluten network formation by interacting directly with specific amino acid residues that resulted in changes in gluten protein composition, specifically the percentage of the unextractable polymeric protein fractions (%UPP). These changes consequently led to remarkable differences in the mixing profiles and microstructural features of the dough, small deformation rheological properties of the gluten and a strain hardening behaviour of both dough and gluten samples.

A secretory leukocyte protease inhibitor variant with improved activity against lung infection.

Secretory leukocyte protease inhibitor (SLPI) is an important respiratory tract host defense protein, which is proteolytically inactivated by excessive neutrophil elastase (NE) during chronic Pseudomonas infection in the cystic fibrosis (CF) lung. We generated two putative NE-resistant variants of SLPI by site-directed mutagenesis, SLPI-A16G and SLPI-S15G-A16G, with a view to improving SLPI's proteolytic stability. Both variants showed enhanced resistance to degradation in the presence of excess NE as well as CF patient sputum compared with SLPI-wild type (SLPI-WT). The ability of both variants to bind bacterial lipopolysaccharides and interact with nuclear factor-κB DNA binding sites was also preserved. Finally, we demonstrate increased anti-inflammatory activity of the SLPI-A16G protein compared with SLPI-WT in a murine model of pulmonary Pseudomonas infection. This study demonstrates the increased stability of these SLPI variants compared with SLPI-WT and their therapeutic potential as a putative anti-inflammatory treatment for CF lung disease.

Nanoencapsulation of ABT-737 and camptothecin enhances their clinical potential through synergistic antitumor effects and reduction of systemic toxicity.

The simultaneous delivery of multiple cancer drugs in combination therapies to achieve optimal therapeutic effects in patients can be challenging. This study investigated whether co-encapsulation of the BH3-mimetic ABT-737 and the topoisomerase I inhibitor camptothecin (CPT) in PEGylated polymeric nanoparticles (NPs) was a viable strategy for overcoming their clinical limitations and to deliver both compounds at optimal ratios. We found that thrombocytopenia induced by exposure to ABT-737 was diminished through its encapsulation in NPs. Similarly, CPT-associated leukopenia and gastrointestinal toxicity were reduced compared with the administration of free CPT. In addition to the reduction of dose-limiting side effects, the co-encapsulation of both anticancer compounds in a single NP produced synergistic induction of apoptosis in both in vitro and in vivo colorectal cancer models. This strategy may widen the therapeutic window of these and other drugs and may enhance the clinical efficacy of synergistic drug combinations.

Acute stress potentiates brain response to milkshake as a function of body weight and chronic stress.

OBJECTIVE: Stress is associated with an increased intake of palatable foods and with weight gain, particularly in overweight women. Stress, food and body mass index (BMI) have been separately shown to affect amygdala activity. However, it is not known whether stress influences amygdala responses to palatable foods, and whether this response is associated with chronic stress or BMI. DESIGN: A total of 14 overweight and obese women participated in a functional magnetic resonance imaging (fMRI) scan as they consumed a palatable milkshake during script-driven, autobiographical, guided imagery of stressful and neutral-relaxing scenarios. RESULTS: We report that a network including insula, somatomotor mouth area, ventral striatum and thalamus responds to milkshake receipt, but none of these areas are affected by stress. In contrast, whereas the left amygdala responds to milkshake irrespective of condition, the right amygdala responds to milkshake only under stressful conditions. Moreover, this right amygdala response is positively associated with basal cortisol levels, an objective measure of chronic stress. We also found a positive relationship between BMI and stress-related increased response to milkshake in the orbitofrontal cortex(OFC). CONCLUSION: These results demonstrate that acute stress potentiates response to food in the right amygdala and OFC as a function of chronic stress and body weight, respectively. This suggests that the influence of acute stress in potentiating amygdala and OFC responses to food is dependent upon individual factors like BMI and chronic stress. We conclude that BMI and chronic stress play a significant role in brain response to food and in stress-related eating.

Food and drug cues activate similar brain regions: a meta-analysis of functional MRI studies.

In healthy individuals, food cues can trigger hunger and feeding behavior. Likewise, smoking cues can trigger craving and relapse in smokers. Brain imaging studies report that structures involved in appetitive behaviors and reward, notably the insula, striatum, amygdala and orbital frontal cortex, tend to be activated by both visual food and smoking cues. Here, by carrying out a meta-analysis of human neuro-imaging studies, we investigate the neural network activated by: 1) food versus neutral cues (14 studies, 142 foci) 2) smoking versus neutral cues (15 studies, 176 foci) 3) smoking versus neutral cues when correlated with craving scores (7 studies, 108 foci). PubMed was used to identify cue-reactivity imaging studies that compared brain response to visual food or smoking cues to neutral cues. Fourteen articles were identified for the food meta-analysis and fifteen articles were identified for the smoking meta-analysis. Six articles were identified for the smoking cue correlated with craving analysis. Meta-analyses were carried out using activation likelihood estimation. Food cues were associated with increased blood oxygen level dependent (BOLD) response in the left amygdala, bilateral insula, bilateral orbital frontal cortex, and striatum. Smoking cues were associated with increased BOLD signal in the same areas, with the exception of the insula. However, the smoking meta-analysis of brain maps correlating cue-reactivity with subjective craving did identify the insula, suggesting that insula activation is only found when craving levels are high. The brain areas identified here are involved in learning, memory and motivation, and their cue-induced activity is an index of the incentive salience of the cues. Using meta-analytic techniques to combine a series of studies, we found that food and smoking cues activate comparable brain networks. There is significant overlap in brain regions responding to conditioned cues associated with natural and drug rewards.

Amygdala response to sucrose consumption is inversely related to artificial sweetener use.

Controversy exists over whether exposure to artificial sweeteners degrades the predictive relationship between sweet taste and its post-ingestive consequences. Here we tested whether brain response to caloric sucrose is influenced by individual differences in self-reported artificial sweetener use. Twenty-six subjects participated in fMRI scanning while consuming sucrose solutions. A negative correlation between artificial sweetener use and amygdala response to sucrose ingestion was observed. This finding supports the hypothesis that artificial sweetener use may be associated with brain changes that could influence eating behavior.

Evidence for an integrated oral sensory module in the human anterior ventral insula.

Taste, which is almost always accompanied by other oral sensations, serves to identify potential nutrients and toxins. The present study was designed to determine the influence of sensory modality (chemesthetic vs. gustatory) and physiological significance (potentially nutritive vs. potentially harmful) on insular response to oral stimulation. Sixteen subjects underwent functional magnetic resonance imaging scanning while receiving 2 potentially nutritive solutions (sucrose and NaCl), 2 potentially harmful solutions (quinine and capsaicin, a chemesthetic stimulus), and a tasteless control solution. We identified a region of anterior ventral insula that responded to oral stimulation irrespective of modality or physiological significance. However, when subjects tasted a potentially nutritive stimulus, the connectivity between the insula and a feeding network including the hypothalamus, ventral pallidum, and striatum was greater than when tasting a potentially harmful stimulus. No differential connectivity was observed as a function of modality (gustatory vs. chemesthetic). These results support the existence of an integrated supramodal flavor system in the anterior ventral insula that preferentially communicates with the circuits guiding feeding when the flavor is potentially nutritive.

Individual differences in the neurophysiology of reward and the obesity epidemic.

The obesity epidemic has unfolded in a matter of decades, not millennia, and therefore cannot be attributed to a drift in the genome. Rather, the temporal characteristics of the epidemic more closely track environmental and lifestyle changes, such as reduced physical activity, increased availability of palatable and energy-dense foods and drinks, and increased acceptance of eating outside of meal time (among others). One important observation is that not everyone is becoming obese. This suggests that individual factors interact with recent environmental changes to predispose some to overeat. One hypothesis that has been gaining traction in the neuroscience community is that individual differences in the neural encoding of foods may predispose some to overeat in the presence of a surplus of energy-dense, palatable foods and drinks. The aim of this review is to highlight several possible ways by which individual differences in the neurophysiology of food reward may lead to overeating.

Relation between obesity and blunted striatal response to food is moderated by TaqIA A1 allele.

The dorsal striatum plays a role in consummatory food reward, and striatal dopamine receptors are reduced in obese individuals, relative to lean individuals, which suggests that the striatum and dopaminergic signaling in the striatum may contribute to the development of obesity. Thus, we tested whether striatal activation in response to food intake is related to current and future increases in body mass and whether these relations are moderated by the presence of the A1 allele of the TaqIA restriction fragment length polymorphism, which is associated with dopamine D2 receptor (DRD2) gene binding in the striatum and compromised striatal dopamine signaling. Cross-sectional and prospective data from two functional magnetic resonance imaging studies support these hypotheses, which implies that individuals may overeat to compensate for a hypofunctioning dorsal striatum, particularly those with genetic polymorphisms thought to attenuate dopamine signaling in this region.

Gustatory agnosia.

OBJECTIVE: To report the assessment of a patient exhibiting gustatory agnosia. METHODS: Preoperative and postoperative neuropsychological, neuroimaging, and chemosensory evaluations were performed in a 39-year-old woman undergoing surgical treatment for intractable epilepsy. RESULTS: Preoperative MRIs showed bilateral (right > left) atrophy in the medial temporal lobes and complete atrophy of the left insula. Evaluation of gustatory function revealed normal suprathreshold intensity estimation, affective evaluation, and detection thresholds but elevated recognition thresholds. A functional neuroimaging study showed activation to stimulation of aversive taste in the left amygdala. Surgical treatment entailed resection from the left medial temporal lobe that included the region of amygdala that had responded to taste. Postoperatively, detection, naming, and intensity estimation for taste remained normal, but the patient was unable to recognize different tastes (sweet, sour, salty, and bitter). A second evaluation 2.5 years after her surgery revealed no change in taste ability. CONCLUSION: The anteromedial temporal lobe has an important role in recognizing taste quality.

The posterior cingulate and medial prefrontal cortex mediate the anticipatory allocation of spatial attention.

The purpose of this study was to identify brain regions underlying internally generated anticipatory biases toward locations where significant events are expected to occur. Subjects fixated centrally and responded to peripheral targets preceded by a spatially valid (predictive), invalid (misleading), or neutral central cue while undergoing fMRI scanning. In some validly cued trials, reaction time was significantly shorter than in trials with neutral cues, indicating that the cue had successfully induced a spatial redistribution of motivational valence, manifested as expectancy. The largest cue benefits led to selectively greater activations within the posterior cingulate and medial prefrontal cortex. These two areas thus appear to establish a neural interface between attention and motivation. An inverse relationship to cue benefit was seen in the parietal cortex, suggesting that spatial expectancy may entail the inhibition of attention-related areas to reduce distractibility by events at irrelevant locations.

Changes in brain activity related to eating chocolate: from pleasure to aversion.

We performed successive H(2)(15)O-PET scans on volunteers as they ate chocolate to beyond satiety. Thus, the sensory stimulus and act (eating) were held constant while the reward value of the chocolate and motivation of the subject to eat were manipulated by feeding. Non-specific effects of satiety (such as feelings of fullness and autonomic changes) were also present and probably contributed to the modulation of brain activity. After eating each piece of chocolate, subjects gave ratings of how pleasant/unpleasant the chocolate was and of how much they did or did not want another piece of chocolate. Regional cerebral blood flow was then regressed against subjects' ratings. Different groups of structures were recruited selectively depending on whether subjects were eating chocolate when they were highly motivated to eat and rated the chocolate as very pleasant [subcallosal region, caudomedial orbitofrontal cortex (OFC), insula/operculum, striatum and midbrain] or whether they ate chocolate despite being satiated (parahippocampal gyrus, caudolateral OFC and prefrontal regions). As predicted, modulation was observed in cortical chemosensory areas, including the insula and caudomedial and caudolateral OFC, suggesting that the reward value of food is represented here. Of particular interest, the medial and lateral caudal OFC showed opposite patterns of activity. This pattern of activity indicates that there may be a functional segregation of the neural representation of reward and punishment within this region. The only brain region that was active during both positive and negative compared with neutral conditions was the posterior cingulate cortex. Therefore, these results support the hypothesis that there are two separate motivational systems: one orchestrating approach and another avoidance behaviours.

Increased intensity perception of aversive taste following right anteromedial temporal lobe removal in humans.

We used a modified version of the Spatial Taste Test to assess taste intensity perception in patients with either left or right temporal resection from the anteromedial temporal lobe (AMTL), and a group of control subjects. Sweet, sour, salty and bitter solutions were applied onto discrete locations of the tongue to stimulate either left or right fungiform, or left or right foliate papillae. Intensity ratings were assessed with the Labeled Magnitude Scale. Subjects also sipped 5 ml of each solution for whole mouth stimulation. Genetically based determinants of taste sensitivity were assessed with ratings of 6-n-propylthiouracil, and covaried from all analyses. As in previous studies, analysis of covariance indicated that the subjects in the right temporal group rated an aversive bitter taste as more intense than did subjects in the control group. In contrast, there were no group differences for sucrose ratings, suggesting that the AMTL may be involved preferentially in processing aversive compared with hedonic tastes. No group x side, or group x location effects were present. These results confirm that removal of the right AMTL in humans results in increased taste intensity/aversiveness perception. This finding complements existing literature indicating that the AMTL is important for processing aversive taste, and suggests that inhibitory mechanisms may play an important role in such processing.

Changes in taste intensity perception following anterior temporal lobe removal in humans.

To investigate the role of the anterior temporal lobe in taste perception, we compared taste intensity estimations made by patients who had removal from either the left or the right anterior temporal lobe for the treatment of intractable epilepsy with a group of healthy control subjects. Estimations were made for five concentrations of each of four different tastes, as well as for five cards of varying saturations of gray, which served as a control task. A cross-modal magnitude estimation procedure was employed in which subjects used distance on a measuring tape to reflect intensity estimation. Distances were then transformed into logs, and the slope and the correlation with stimulus concentration or saturation was calculated. Correlation was taken as a measure of accuracy of estimation and slope was taken as a measure of perceived intensity. As predicted, repeated measures analysis of variance (ANOVA) revealed a significant difference between the control group and both patient groups in taste intensity estimations, but not for grayness, reflecting the importance of the anterior temporal lobe in low-level gustatory but not visual perception. Additionally, repeated measures ANOVA for slopes indicated that subjects in the right temporal group rated the bitter taste as more intense than did subjects in other groups, possibly reflecting increased intensity perception of the unpleasant bitter taste.

The lipid composition of drusen, Bruch's membrane, and sclera by hot stage polarizing light microscopy.

PURPOSE: To detect and identify, in situ, the lipid composition of drusen, diffuse Bruch's membrane deposits, and sclera in aging human eyes using hot-stage polarizing microscopy (HSPM), a method that allows qualitative determination of lipid subtypes within histologic sections based on morphology and melting temperatures of liquid crystals as monitored by birefringence during heating and cooling. METHODS: Full-thickness buttons of the central macula and the periphery of human eyes from 17 patients were fixed in 5% calcium-buffered formalin. Frozen sections were stained with oil red O or Sudan black or were analyzed by HSPM. RESULTS: Birefringent anisotropic droplets ("maltese crosses") with melting characteristics of cholesterol esters were identified within diffuse Bruch's membrane deposits, drusen, and sclera. Deposits that melted from crystal to oil without any maltese cross formation when cooled were present in the sclera and are consistent with triglyceride-rich deposits. Deposits with optical properties consistent with phospholipids were identified in a single aged eye. Eyes from young donors did not show these changes. CONCLUSIONS: HSPM is a valuable technique for evaluating the nature of lipid deposits in aging eyes. Further studies are warranted to determine whether similar changes are also present in eyes with age-related macular degeneration.

Atomic resolution structure analysis of beta' polymorph crystal of a triacylglycerol: 1,2-dipalmitoyl-3-myristoyl-sn-glycerol.

The crystal structure of the beta'-2 form of a mixed chain triacylglycerol (TAG), 1,2-dipalmitoyl-3-myristoyl-sn-glycerol (PPM), was determined to a final reliability factor of 0.074. This work is the first to resolve the atomic-level structure of the beta' polymorph, which is of the highest functionality among multiple polymorphs in asymmetric TAG. In particular, fat crystals present in food emulsions are in beta', whose transformation into beta causes deterioration in their physical properties. beta'-2, one of the two beta' forms of PPM, forms a monoclinic unit cell with a space group of C2; Z = 8, a = 16.534(5) A, b = 7.537(2) A, c = 81.626(9) A; beta = 90.28(2) degrees, V = 10171(3) A(3), density = 1.018 g/cm(3), and mu = 4.96 cm(-1). The following characteristics were obtained: 1) two asymmetric units, named A and B, form a hybrid-type orthorhombic perpendicular subcell; 2) the two asymmetric units reveal different glycerol conformations: trans for sn-1 palmitic acid and sn-2 palmitic acid, but gauche for sn-3 myristic acid in A; and trans for sn-2 palmitic acid and sn-3 myristic acid, but gauche for sn-1 palmitic acid in B; 3) a unit lamellae reveals a four-chain-length structure consisting of two double-layer leaflets; 4) the two double-layer leaflets are combined end-by-end in a unit lamellae; and 5) the chain axes are alternatively inclined against the lamellar interface. -- Sato, K., M. Goto, J. Yano, K. Honda, D. R. Kodali, and D. M. Small. Atomic resolution structure analysis of beta' polymorph crystal of a triacylglycerol: 1,2-dipalmitoyl-3-myristoyl-sn-glycerol. J. Lipid Res. 2001. 42: 338--345.

The N-terminal 17% of apoB binds tightly and irreversibly to emulsions modeling nascent very low density lipoproteins.

The N-terminal 17% of apolipoprotein B (apoB-17) readily associates with dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLV) to form large (240-A diameter) discoidal particles. Because apoB is normally secreted with triacylglycerol (TAG)-rich lipoproteins, we studied the binding of apoB-17 to triolein-rich emulsions modeling nascent TAG-rich very low density-like lipoproteins. Emulsions with the following composition (by weight) were prepared: 85--89% triolein, 1.1--1.4% cholesterol, and 10--14% phosphatidylcholines (PC) including either egg yolk (EY)-, dimyristoyl (DM)-, or dipalmitoyl (DP)-PC representing (at 25 degrees C), respectively, a fluid surface, a surface at transition, and a mainly solid surface. The respective sizes were 1,260 +/- 500, 1,070 +/- 450, and 830 +/- 300 A mean diameter. The emulsions were incubated with conditioned medium containing apoB-17, and then reisolated by ultracentrifugation. Analysis of the emulsion-bound proteins by gel electrophoresis showed that all three emulsions bound primarily apoB-17. The DPPC emulsions bound more apoB-17 than EYPC or DMPC emulsions. Immunoaffinity-purified apoB-17 exhibited saturable, high affinity binding to EYPC and DPPC emulsions. The respective K(d) values were 32 +/- 23 and 85 +/- 27 nM and capacities (N) were 10 and 58 molecules of apoB-17 per particle. When apoB-17 bound to emulsions was incubated with DMPC MLV at 26 degrees C for 18 h, it remained bound to the emulsions, indicating that once bound to these emulsions it is unable to exchange off and solubilize DMPC into discs. In contrast, apoE-3 bound to emulsions dissociated from the emulsions when incubated with DMPC MLV and formed discs.Thus, apoB-17 binds strongly and irreversibly to emulsions modeling nascent lipoproteins. It therefore may play an important role in the stabilization of nascent VLDL and chylomicrons.- Herscovitz, H., A. Derksen, M. T. Walsh, C. J. McKnight, D. L. Gantz, M. Hadzopoulou-Cladaras, V. Zannis, C. Curry, and D. M. Small. The N-terminal 17% of apoB binds tightly and irreversibly to emulsions modeling nascent very low density lipoproteins. J. Lipid Res. 2001. 42: 51;-59.

Morphology of sodium deoxycholate-solubilized apolipoprotein B-100 using negative stain and vitreous ice electron microscopy.

The primary and secondary structures of apolipoprotein B-100 (apoB-100) are well established. Previous morphological studies have suggested that apoB is a long, flexible, threadlike molecule that encircles the low density lipoprotein (LDL) particle. Several large domain regions of the protein have been observed in frozen hydrated LDL and may be involved in anchoring of the protein to the lipid surface of LDL. Calorimetric studies of sodium deoxycholate (NaDC)-solubilized apoB indicated a similar number of independently melting domains. We therefore undertook a morphological study of NaDC-solubilized apoB-100 using negative stain and vitreous ice cryoelectron microscopy, a nonperturbing preservation technique. Negative staining experiments were performed in two ways: 1) grids were pulled through NaDC-containing buffer surfaces on which monolayers of apoB had been promoted, or 2) apoB molecules were allowed to diffuse onto carbon surfaces of grids that were floated on sample droplets. Vitrified molecules of apoB were obtained by plunging a thin fluid layer of protein adhered to a holey carbon-coated grid into supercooled ethane and by preserving the molecules in liquid nitrogen. The majority of molecules prepared in negative stain and vitreous ice were curved or arced and had alternating thin and thick regions. In negative stain, the apoB molecules lay on the grid perpendicular to the electron beam and had a mean length of 650 A. In vitreous ice the molecules were randomly oriented and their images ranged from 160 to 650 A in length. Vitrified molecules provided visualization of one or two beaded regions. Similar regions were observed in negative stain but the overall thickness was two to three times greater. Some vitrified molecules contained ribbon-like portions. Our study supports previously obtained data on molecule length but suggests that negative staining overestimates molecule width. These first images of vitrified NaDC-solubilized apoB-100 confirm the long, flexible, beaded thread morphology of the molecule and support the unique potential of this technique when coupled with proper molecule orientation and antibody labeling to correlate the tertiary structure of apoB seen in the intact particle with that of the isolated molecule.

Specificity of lipid incorporation is determined by sequences in the N-terminal 37 of apoB.

The N-terminal 17% of apolipoprotein B (apoB-17) is secreted lipid-poor while apoB-41 particles are secreted with a triacylglycerol (TAG)-rich core. Thus, the sequence between apoB-17 and apoB-41 is necessary for the assembly of TAG-rich lipoproteins. To delineate this region, C127 cells were permanently transfected to secrete the N-terminal 29, 32.5, or 37% of apoB. Density gradient centrifugation showed that secreted apoB-29, apoB-32.5, and apoB-37 had peak densities of 1.25, 1.22, and 1.16 g/mL and percent lipid of particle weights of 30, 37, and 49%, respectively. Calculated anhydrous particle diameters were: apoB-29 = 81 A, apoB-32.5 = 88 A, and apoB-37 = 101 A. Immunoprecipitated particles labeled with [(3)H]oleate showed that, as apoB length increased from apoB-29 to apoB-32.5 and apoB-37, the number of TAG (core) molecules per apoB particle increased almost 16-fold from 8 to 32 to 124, while phospholipids and diacylglycerols (surface lipids) increased only slightly from 71 to 87 to 97 molecules, respectively. Thus, sequences in the C-terminus of apoB-29 bind phospholipids and diacylglycerols, sequences between apoB-29 and apoB-32.5 augment TAG binding and sequences between apoB-32.5 and apoB-41 account for the marked incorporation of TAG at a rate of approximately 1 TAG per 2 amino acids. Cryoelectron micrographs of isolated apoB-37 particles revealed mostly spherical particles of approximately 110 A (11.0 nm) with an electron lucent center, consistent with these particles having a TAG core. We suggest that the predicted amphipathic beta-sheets beginning at apoB-29, starts to preferentially recruit core lipids into apoB and propose that the consistent presence of DAG in the secreted particles may have a role in fission of the nascent lipoprotein particles from the endoplasmic reticulum membrane.