The pedunculopontine tegmental nucleus and responding for sucrose reward.

Pedunculopontine tegmental nucleus (PPTg) lesions in rodents lead to increased sucrose consumption, but the psychological deficit behind this remains uncertain. To understand better the relationship between consumption of, and motivation for, sucrose, the authors trained rats to traverse a runway for 20% or 4% sucrose solution; after 7 days, concentrations were reversed. Control rats consumed more 20% than 4% sucrose solution and promptly altered run times in response to concentration change. PPTg-lesioned rats consumed normal quantities of 4% but more 20% sucrose solution than controls and took longer to alter their runway time following the concentration change. These data suggest that lesions of the PPTg do not alter motivation per se and might be better understood as inducing a response selection deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spontaneous improvement of visual fusion by correction of minor anisometropia (author''s transl)

A comparison was made between biphasic brain heart infusion medium without and with 15% sucrose in vented blood culture bottles. A higher recovery rate (P less than 0.01) of fungi was noted in the medium without sucrose.     

Enthalpy relaxation in binary amorphous mixtures containing sucrose

PURPOSE: To compare the enthalpy relaxation of amorphous sucrose and co-lyophilized sucrose-additive mixtures near the calorimetric glass transition temperature, so as to measure the effects of additives on the molecular mobility of sucrose. METHODS: Amorphous sucrose and sucrose-additive mixtures, containing poly(vinylpyrrolidone) (PVP), poly(vinylpyrrolidone-co-vinyl-acetate) (PVPNA) dextran or trehalose, were prepared by lyophilization. Differential scanning calorimetry (DSC) was used to determine the area of the enthalpy recovery endotherm following aging times of up to 750 hours for the various systems. This technique was also used to compare the enthalpy relaxation of a physical mixture of amorphous sucrose and PVP. RESULTS: Relative to sucrose alone, the enthalpy relaxation of co-lyophilized sucrose-additive mixtures was reduced when aged for the same length of time at a comparable degree of undercooling in the order: dextran approximately PVP > PVPNA > trehalose. Calculated estimates of the total enthalpy change required for sucrose and the mixtures to relax to an equilibrium supercooled liquid state (deltaHinfinity) were essentially the same and were in agreement with enthalpy changes measured at longer aging times (750 hours). CONCLUSIONS: The observed decrease in the enthalpy relaxation of the mixtures relative to sucrose alone indicates that the mobility of sucrose is reduced by the presence of additives having a Tg that is greater than that of sucrose. Comparison with a physically mixed amorphous system revealed no such effects on sucrose. The formation of a molecular dispersion of sucrose with a second component, present at a level as low as 10%, thus reduces the mobility of sucrose below Tg, most likely due to the coupling of the molecular motions of sucrose to those of the additive through molecular interactions.     

Simultaneous contrast: Evidence from licking microstructure and cross-solution comparisons.

The microstructure of rats' licking responses was analyzed to investigate both “classic” simultaneous contrast (e.g., Flaherty & Largen, 1975) and a novel discrete-trial contrast procedure where access to an 8% test solution of sucrose was preceded by a sample of either 2%, 8%, or 32% sucrose (Experiments 1 and 2, respectively). Consumption of a given concentration of sucrose was higher when consumed alongside a low rather than high concentration comparison solution (positive contrast) and consumption of a given concentration of sucrose was lower when consumed alongside a high rather than a low concentration comparison solution (negative contrast). Furthermore, positive contrast increased the size of lick clusters while negative contrast decreased the size of lick clusters. Lick cluster size has a positive monotonic relationship with the concentration of palatable solutions and so positive and negative contrasts produced changes in lick cluster size that were analogous to raising or lowering the concentration of the test solution respectively. Experiment 3 utilized the discrete-trial procedure and compared contrast between two solutions of the same type (sucrose-sucrose or maltodextrin-maltodextrin) or contrast across solutions (sucrose-maltodextrin or maltodextrin-sucrose). Contrast effects on consumption were present, but reduced in size, in the cross-solution conditions. Moreover, lick cluster sizes were not affected at all by cross-solution contrasts as they were by same-solution contrasts. These results are consistent with the idea that simultaneous contrast effects depend, at least partially, on sensory mechanisms. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Conformational analysis of potent sweet taste ligands by nuclear magnetic resonance, computer simulations and X-ray diffraction studies

Four potent sweet-tasting molecules, N-(3,3-dimethylbutyl)-L-aspartyl-L-phenylalanine methylester 1 (7000 times more potent than sucrose), N-(3,3-dimethylbutyl)-L-aspartyl-D-valine (S)-alpha-ethylbenzylamide 2 (3000 time more potent than sucrose), L-aspartyl-D-valine (R)-alpha-methoxymethylbenzylamide 3 (1350 times more potent than sucrose and L-aspartyl-(1R,2S,4S)-1-methyl-2-hydroxy-4-phenylhexylamide 4 (2500 times more potent than sucrose) were studied by 1H NMR and computer simulations. These flexible molecules adopt multiple conformations in solution. The "L-shaped" structure, which we believe to be responsible for sweet taste is accessible to all four compounds in solution. Extended conformations with the AH and B-containing moieties in the +y-axis and the hydrophobic group X pointing in the y-axis have also been observed for all four sweeteners. For compounds 1 and 3, the solid-state conformations were determined by X-ray diffraction studies. These results demonstrate that compounds 1 and 3 adopt an "L-shaped" structure even in the crystalline state. The extraordinary potency of the N-alkylated compound 1 compared with the unsubstituted Asp-Phe-OMe may be explained by the effect of a second hydrophobic binding domain in addition to interactions arising from the "L-shaped" structure.     

Within-subjects positive and negative contrast effects in rats.

Conducted 4 experiments, using a total of 47 Sprague-Dawley albino rats. Ss were given alternating 1-min access periods to 2 tubes containing either 32 or 4% sucrose solutions for daily 6-min test sessions. Lick rate for 32% was higher under comparison (32 vs 4) than noncomparison (32 vs 32) conditions; and lick rate for 4% was lower under comparison conditions (4 vs 32) than under noncomparison conditions (4 vs 4). All sucrose conditions were varied within Ss, and both positive and negative contrast were obtained with a small n. In addition to lick rate, intake and latency measures revealed contrast effects. Deprivation conditions altered latency but not lick rate measures of contrast. Reducing the test session to 3 min (alternating 30-sec access periods) did not greatly affect contrast. Additional experiments provided evidence for distinct within- and between-days contrast effects, as well as a between-groups contrast effect. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gustatory thalamus lesions eliminate successive negative contrast in rats.

Neurologically intact rats expecting to receive a high-value reward (1.0 M sucrose), licked less for an unexpected low-value reward (0.15% saccharin) than did control subjects that only received the saccharin solution. This reward comparison effect, termed successive negative contrast, was eliminated after bilateral electrolytic lesions of the gustatory thalamus. The results are discussed in terms of disrupted memory processes that may have rendered the lesioned rats incapable of computing the relative reward value of the available solution (0. 15% saccharin) with respect to the memory of the preferred solution (1.0 M sucrose). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sucrose and fructose have qualitatively different flavors to rats

Previous studies suggest that rats might be able to discriminate between sucrose and fructose, but no previous study has examined this possibility in much detail. Rats were conditioned to avoid either sucrose or fructose by injecting them with lithium chloride when they drank these substances. Control rats were given the same injections but were not exposed to either sugar during training. After training, the rats were given a choice of fructose vs. sucrose. Data from control rats provided information about the relative taste intensity of the sugars. If the sugars possess only a single gustatory quality, control rats should prefer the sweeter sugar; under this assumption, sucrose appears to be two-four times sweeter than fructose. The two sugars share a common taste because rats trained to avoid sucrose avoided fructose when the fructose concentration was much greater than the sucrose concentration. Nevertheless, the two sugars are discriminable because, when the apparent sweetness of the sugars was matched, rats showed a greater aversion to the sugar they were trained to avoid. Aversions to sucrose and fructose also generalized to maltodextrins, but sucrose may have a somewhat greater maltodextrin flavor than does fructose. It is proposed that the biological function of maltodextrin taste is to allow animals to sense the ratio of glucose to fructose in foods.     

Sucrose intake in Germany

The present investigation reevaluated the German National Food Consumption Survey in order to obtain data on sucrose intake and food sources of sucrose intake in Germany. Moreover, it focused on the effect of sucrose intake on nutrient intake. By means of the food composition data base Bundeslebensmittelschlüssel, version II.2, 7-days dietary records of a representative sample of 15,838 persons aged 4 years and older were analyzed. The relation between sucrose and nutrients intake was investigated by variance and regression analyses. Low, moderate, and high sucrose intake categories were defined by means of sucrose density quartiles and comparisons were made for the percentages of persons meeting the German nutrient intake recommendations. Mean daily sucrose intake ranges between 43.2 g/d (f, 51-64 years) and 82.3 g/d (m, 13-14 years). The mean contribution of sucrose to total energy intake is highest with 14% in young age (4-6 years) and decreases to 9% and 7% in 51-64 year old women and men, respectively. The food groups "table sugar", "confectionery and ice cream", "biscuits, cake and pastries", "preserves", "dairy products", and "non-alcoholic beverages" are the main sucrose sources with varying importance in different age groups. The average amount of naturally occurring sucrose in the Germans' diet is estimated to 15-25% of total sucrose intake. Sucrose contributes 80-90% to total disaccharides intake in Germany. With each gram of sucrose the intake of energy rises on the average by 12.5 kcal (52.4 kJ), of protein by 0.3 g (9% of the energy increase), of fat by 0.5 g (34%), and of carbohydrates by 1.8 g (57%). Consequently, the higher the sucrose content of a diet, the lower is the contribution of fat to total energy intake. In contrast, the energy-adjusted effect of sucrose was found to be negative for energy-providing nutrients (except mono- and disaccharides) as well as for all the selected micronutrients, except calcium, vitamin E, vitamin C, and dietary fiber. Accordingly, the comparison between moderate and high sucrose consumers revealed a lower percentage of persons meeting nutrient intake recommendations in the high sucrose category under the condition of a comparable energy intake. This unfavorable effect of high sucrose intake is most prominent in 4-6 year old boys and girls as the groups with the highest sucrose intake. Since from the present data no exact figure for a sucrose or sugars intake recommendation can be deduced, it is suggested to keep on the WHO recommendation for a moderate sugar intake of 10% of energy intake.     

Assessment of the taste interaction between two qualitatively similar-tasting substances: A comparison between comparison rules.

The taste interaction between sucrose and fructose was assessed by using three different comparison procedures: the summated response comparison, the factorial plot comparison, and the equimolar comparison rule. The perceived sweetness intensities were obtained on a ratio scale by using a functional measurement approach in combination with a two-stimulus procedure. The conclusions obtained from each of the three comparison rules were identical. The taste interaction between sucrose and fructose could be explained to a large extent, but not completely, by the apparent taste "interactions" within sucrose and fructose as single substances. It is argued that the apparent taste interaction within a large number of single sugars and between two of these sugars in a mixture is somewhat synergistic at low sweetness levels, additive at intermediate sweetness levels, and suppressive at high sweetness levels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cisatracurium

Cisatracurium is one of ten isomers that form the racemic mix of atracurium (51W89 or 1 R-cis, 1'R-cis atracurium). It is three times more potent than atracurium itself and hemodynamically stable thanks to its scarce release of histamine. Cisatracurium is hydrolyzed mainly by the pathway of Hofmann (77%) and to a lesser degree it is metabolized by organ-dependent modes (mainly by the kidney (16%)). Dose therefore hardly needs to be changed for elderly patients or those with liver, kidney or cardiovascular disease. The calculated ED95 is 0.05 mg.kg-1 (0.04 mg.kg-1 in children), although a dose two to four times greater is used under clinical conditions to shorten tracheal intubation time because of low onset of blockade, particularly in comparison with rocuronium. The period of deep blockade (lack of response to neurostimulation) is prolonged by the higher dose, but recovery is dose-independent and recovery indices are similar. Cisatracurium has proven useful in intensive care because of its hemodynamic stability, which is comparable to that of steroid derivatives but with faster recovery from blockade once administration is discontinued. Its metabolism predominantly through Hofmann's pathway, with less laudanosine formation than is produced by atracurium, is also appreciated. Cisatracurium is described as the nondepolarizing muscle relaxant of choice for medium-to-long-term surgery on hemodynamically unstable patients or those with kidney or liver disease, and for neuromuscular blockade in intensive care.     

Pyruvate improves myocardial tolerance to reperfusion injury by acting as an antioxidant: a chemiluminescence study

The utilization of various substrates by sperm from the cauda epididymidis of the tammar was examined because the major naturally occurring sugar in the semen of this species is N-acetyl-D-glucosamine (NAG) and not furctose, as in eutherian mammals. The sperm displayed a high level of endogenous respiration that supported motility for relatively prolonged periods of time in vitro. They also metabolised exogenous 14C-labelled glucose, NAG, sucrose, and acetate through glycolytic and/or oxidative processes to produce lactate and 14CO2 at varying rates. The rate of uptake of NAG by tammar sperm was about four times greater than that of other substrates. Glucose and/or NAG stimulated the rate of oxygen consumption by about 20%, but acetate stimulated oxygen consumption by more than 40%. The most striking findings were that NAG almost completely inhibited the oxidation of glucose and sucrose by the sperm and depressed the uptake of glucose, 3-O-methylglucose, and sucrose. Acetate oxidation also was inhibited by NAG, but only by about 50%. Tammar sperm generated substantial amounts of free glucose during incubation with NAG, but this and the inhibitory effects of NAG on glucose oxidation were not mimicked by rat sperm. It is proposed that tammar sperm fail to oxidise glucose in the presence of NAG because of the rapid cellular uptake of NAG relative to glucose. Also, the intracellular glucose and acetate liberated from NAG would compete with exogenous glucose for processing in the Embden-meyerhof and tricarboxylic acid (TCA) cycle pathways. It is also suggested that tammar sperm oxidise sucrose after extracellular hydrolysis into its glucose and fructose components. The biological implications of these metabolic and transport properties of tammar sperm have as yet to be determined.     

Occurrence and distribution of sucrose-metabolizing enzymes in oral streptococci

Specific growth rates, growth yields, and the level and cellular distribution of three sucrose-metabolizing enzyme activities were determined for seven oral streptococci (Streptococcus mutans strains E49, BHT, 10449, SL-1, and LM-7, S. sanguis 10558, and S. salivarius 25975). Cultures were grown in a fermentor at pH 6 with either 20 mM glucose or 10 mM sucrose. Generation times varied between 21 and 70 min. Whereas some strains grew 10 to 50% more slowly with sucrose than with glucose, others did not. Growth was always logarithmic, and the growth yields were similar. Glcosyl transferase (EC 2.4.1.5) was largely extracellular; in sucrose cultures it was appreciably lower, but no major shift to a cell-associated form was found. In glucose cultures, the activity varied between 4 and 140 IU per 6-liter culture. The glucan formed was mostly or exclusively water insoluble. Glcosyl transferase was stimulated weakly (60% or less) by various dextrans. Fructosyl transferase (EC 2.4.1.10) was primarily extracellular (except in glucose cultures of S. salivarius) and varied between 0 and 337 IU/culture. In S. salivarius, the extracellular fructosyl transferase was induced by sucrose. In all S. Mutans cultures, the total fructosyl transferase activity was lower after growth with sucrose. All strains had extra- and intracellular invertase (EC 3.2.1.26) activity. Total levels varied between 210 and 3,500 IU/culture. Less extracellular activity was present in sucrose cultures. Only S. salivarius had appreciable activity in the cellular particulate fraction. Invertase activity was significantly higher than the combined glucosyl and fructosyl transferase activities in all cultures.     

Effects of intrahippocampal administration of colchicine on incentive contrast and on radial maze performance.

Examined the behavior of rats given intradentate injections of colchicine (COL). In Exp 1, COL-treated, artificial cerebrospinal fluid (CSF)-treated, and untreated Ss did not differ in the intake of 32% and 4% sucrose solutions, nor did they differ in degree of successive negative contrast when the 32% solution was changed to 4% sucrose. In Exp 2, the COL-treated and CSF-treated Ss did not differ in degree of suppression in the intake of a 0.15% saccharin solution when it preceded 32% sucrose in once-daily pairings (anticipatory contrast), nor did they differ in reversal performance when saccharin–sucrose and saccharin–saccharin pairings were reversed. In Exp 3, the COL-treated Ss were substantially impaired in radial-arm maze performance compared with CSF-treated controls. Results suggest that a completely functioning hippocampus is not necessary for the memory of reward quality, the comparison of rewards, the suppression of behavior when reward is decreased, the formation of associations between 2 levels of reward, and the reversal of this association, as long as these processes are reflected in consummatory behavior. Data are interpreted in terms of differences between instrumental behavior and sensory memory and/or consummatory behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attenuated Dopamine Efflux in the Rat Nucleus Accumbens During Successive Negative Contrast.

Rats shifted from 4% to 32% sucrose displayed successive negative contrast by initiating significantly fewer bouts of licking than control rats maintained on 4% sucrose. No significant increase in dopamine (DA) efflux in the nucleus accumbens (NAc) was observed during consumption of 4% sucrose by rats shifted from 32%. In contrast, consumption of 4% sucrose by control rats was accompanied by a significant increase in DA efflux in the NAc, which remained elevated 10 min postconsumption. These data are consistent with the hypothesis that DA efflux in the NAc reflects the current incentive valence of sucrose reward and its influence on initiation of individual bouts of sucrose consumption. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temperature and activity responses to sucrose concentration reductions occur on the 1st but not the 2nd day of concentration shifts, and are blocked by low, constant glucocorticoids.

Previous findings (N. Pecoraro, J. Chou-Green, & M. F. Dallman, 2003; N. Pecoraro & M. F. Dallman, 2005) indicated that unexpected reductions in sucrose concentration in once daily meals result in a febrile response on the 1st, but not the 2nd day of a concentration shift. This study shows that this day-specific fever is blocked by adrenalectomy accompanied by constant low corticosterone replacement. Rats implanted with telemetry probes were adrenalectomized and given low-corticosterone pellets or were sham operated. Food-restricted rats were given 2 rounds of sucrose concentration downshifts, as follows: 32% sucrose (14 days), 4% sucrose (6 days), 32% sucrose (4 days), and 4% sucrose (4 days). Intact rats showed more pronounced anticipation of the sucrose than did rats having low, clamped corticosterone. Only intact rats showed a 4-hr, postshift temperature burst on the 1st, but not the 2nd day of the shift to 4% sucrose, during both rounds of shifting. Increased activity accompanied the fever. These data confirm previous findings, show them to be dependent on high corticosterone, and appear to be related to a host of day-specific alterations in other motor outflows following unexpected downward shifts in palatable sucrose concentrations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimised dietary regimens for the laboratory maintenance of Phlebotomus langeroni nitzulescu (Diptera: Psychodidae)

The optimal feeding conditions for laboratory colonies of Phlebotomus langeroni, the vector of infantile visceral leishmaniasis in Egypt, were investigated. Sugarmeals were offered only before bloodmeals (the SB regimen), only after blood (BS), or both before and after blood (SBS). In each regimen, three different solutions of sucrose (10%, 30% and 50%, w/v) were tested as the source of sugarmeals. In general, the concentration of sucrose used had no significant effect on female longevity, although the longest lived females were those fed on 30% sucrose. Females on the BS regimen were the longest lived whereas those on the SB were the shortest lived. Sucrose concentration did not significantly affect total fecundity, the number of eggs oviposited by females, or the proportion of each egg batch that remained unlaid, but female flies fed 30% sucrose laid more eggs than those fed 10% or 50%, and SBS females laid more eggs than SB or BS. Sucrose concentration and dietary regimen both significantly affected the proportion of laid eggs that hatched, 30% sucrose giving significantly higher proportions than 10% or 50% (in all tested regimens), and the SBS regimen producing higher proportions than the SB or BS. Provision of 30% sucrose before and after bloodmeals is therefore recommended for the laboratory maintenance of P. langeroni.     

Sucrose, ethanol, and sucrose/ethanol reinforced responding under variable-interval schedules of reinforcement

Adding sweeteners to ethanol solutions is a common method of inducing rats to consume ethanol. However, it has usually been assumed that it is the sweet taste and/or the calories contained in the sweet solution that controls consumption. The present experiment examined the role of ethanol in controlling responding reinforced by ethanol or an ethanol/sucrose mixture compared with sucrose solutions of various concentrations. After initiation to self-administer 10% (v/v) ethanol using the sucrose-substitution method, rats were trained to respond under a concurrent VI 5" VI 5" schedule. During one condition, responding on one lever was reinforced by the presentation of 10% ethanol, and responding on a second lever was reinforced by water or one of the following sucrose solutions: 1% (w/v), 1.5%, 2%, 2.5%, 3%, and 5%. During a subsequent condition, responding reinforced by a 10% ethanol/2% sucrose mixture was compared under the concurrent schedule with responding reinforced by water, 2%, 2.5%, 3%, 5%, or 10% sucrose (w/v). The results indicated that the ethanol or ethanol/sucrose mixture maintained more responding than did sucrose solutions that were sweeter. Data support the conclusion that, after initiation, the taste and/or pharmacological effects of ethanol had become an important component of the reinforcing stimulus independent of the sweetener.     

Fractionation on the microscale of brain polyribosomes by electrophoresis on acrylamide gels

A method is described for brain polyribosome fractionation by acrylamide gel electrophoresis. Brain polyribosomes were run in 2.0% gels in quartz capillaries of 800 mum inner diameter where the gels were supported by capillary force. The gels could then be ultraviolet-scanned in situ. Amounts of brain polyribosomes as small as 10-10(-3) A260nm unit could be analysed by this method. The method was checked by running a macroscale-prepared brain polyribosome sample. The various electrophoretic bands obtained showed a favourable A260nm: A280 ratio. A short RNase treatment caused the disappearance of the slowly migrating bands and the emergence of a predominant band migrating faster than the dimer. The various polyribosomal bands were then identified by comparison with the mobility of polyribosome fractions taken from a sucrose gradient fractionation. Finally, the electrophoretic pattern of brain polyribosomes compared favourably with the pattern obtained by the classic method of sucrose gradient sedimentation. The electrophoretic fractionation of polyribosomes prepared from one rat hippocampus (80 mg) is presented.     

Epidemiological analysis defining concurrent outbreaks of Serratia marcescens and methicillin-resistant Staphylococcus aureus in a neonatal intensive-care unit

OBJECTIVE: To determine the plasma glucose and insulin responses of various doses of glucose, sucrose, fructose and white bread in normal human subjects. DESIGN: Plasma glucose and insulin were measured before and at various times after 8 subjects ate 13 different test meals in randomized order on separate days after an overnight fast. Test meals consisted of 500 ml of tea or water to which was added either nothing, 25, 50, or 100 g of glucose or sucrose, 25 or 50 g fructose, 50 g glucose plus 50 g fructose, or a 25, 50 or 100 g carbohydrate portion of white bread. The glycaemic (GI) and insulinaemic index (II) values of the sugars were calculated by expressing the incremental areas under the plasma glucose and insulin curves (AUC) after glucose, sucrose and fructose as a percentage of the respective AUC after white bread containing the same amount of carbohydrate. SETTING: University teaching hospital clinical nutrition centre. SUBJECTS: Lean, normal subjects (4 male, 4 female) 21-33 y of age. RESULTS: Plasma insulin responses increased nearly linearly as carbohydrate intake increased from 0 to 100 g, but glycaemic responses increased by only 68% and 38% as carbohydrate intake increased from 25 to 50 g and 50 to 100g, respectively. The GI and II values of glucose, 149+/-16 and 147+/-18, respectively, were significantly greater than those of bread (100; P<0.05), while the values for fructose, 16+/-4 and 22+/-3 were significantly less than those of bread (P<0.001). GI values did not differ significantly from II values. CONCLUSIONS: It is concluded that, in normal subjects, as carbohydrate intake is increased from 0 to 100 g, plasma insulin responses increase at a greater rate than plasma glucose responses. The insulinaemic responses elicited by glucose, sucrose or fructose are similar to those that would be expected from a starchy food with the same glycaemic index.