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PubMed1991

Increase of sialylated tetraantennary sugar chains in parallel to the higher lung-colonizing abilities of mouse melanoma clones.

The N-linked sugar chains of melanoma cell membrane from five murine B16 melanoma clones (F1, F10, BL6, W1-4, and C4-1) with different degrees of metastatic abilities after intravenous and intrafootpad injections were released quantitatively as oligosaccharides by hydrazinolysis, and their structures were analyzed by serial lectin column chromatography, Bio-Gel P-4 column chromatography, and sequential glycosidase digestion. Sugar chain structures of each clone have shown to consist of the same elemental oligosaccharides, but to differ in their percent compositions. More than 84% of the neutral oligosaccharides were high mannose-type sugar chains. Most complex-type sugar chains were sialylated, of which the major structure was tetraantennary sugar chain. Highly lung-colonizing F10 cells had 1.4 and 1.7 times more non-repeated tetraantennary sugar chains than moderately colonizing F1 and C4-1 cells, respectively, and 2.5 times more than poorly colonizing W1-4 cells. BL6 cells, which are also highly lung-colonizing, had 1.5 and 1.9 times more non-repeated tetraantennary sugar chains than F1 and C4-1 cells, respectively, and 2.8 times more than W1-4 cells. These results suggest that increase of sialylated tetraantennary complex-type sugar chains without N-acetyllactosamine repeating units of B16 melanoma cells might correlate with the higher lung-colonizing ability after intravenous injection.

Animals↗

PubMed1996

A survey of factors influencing the prescribing of sugar-free medicines for children by a group of general medical practitioners in Northern Ireland.

Factors which influence the prescribing of sugar-free medicines by 47 general medical practitioners were examined by means of questionnaire. The doctors all practise in the Newry and Mourne district of the Southern Health and Social Services Board, Northern Ireland. Twenty-six (55%) of the doctors stated that they support the principle of prescribing sugar-free medicines for children; the same number stated that they oblige parental requests and 14 (30%) stated that they frequently prescribe a common group of sugar-free medicines. However, only 14 (30%) of the doctors considered that their knowledge of sugar-free medicines was up-to-date. The main sources of information about sugar-free preparations were drug company travelling representatives and professional journals, but a few doctors learned of this issue from other professionals, including dental practitioners. The majority of doctors (especially those with a practice policy of prescribing sugar-free medicines) felt it was important to prescribe sugar-free preparations for all children, not only for those requiring long-term medication. The results show that there is a reasonable level of interest in this issue among the doctors in the area, but that there is an on-going need for further encouragement and provision of information for them, in order to increase as far as possible the use of sugar-free preparations for children.

Adolescent↗

PubMed2005

Low calorie commercial sugar is a sensitive marker of glomerular filtration rate.

BACKGROUND: Glomerular filtration rate (GFR) in humans and animals might be determined with precision by measuring the clearance of an ideal marker, such as inulin. However, the use of inutest, an inulin analog, is limited by its cost and accessibility. The present study tested whether low calorie commercial sugar (LC sugar) can be used to measure GFR during normal and renal dysfunction. METHODS: Two groups of 6 male Wistar rats weighing 300 to 350 g were included. One group was treated with a daily dose of cyclosporine (CsA) 30 mg/kg subcutaneously for 7 days and the other group was formed by nontreated control rats. In one half of each group, GFR was evaluated by using inutest and in the other half by using LC sugar. GFR was also evaluated by using a wide LC sugar plasma concentration range in an additional group. RESULTS: In nontreated rats, the mean GFR evaluated with LC sugar was 2.2 +/- 0.1 mL/min. This value is equal to that obtained with inutest: 2.3 +/- 0.1 mL/min. CsA administration produced a significant reduction of renal blood flow and renal function. The GFR reduction induced by CsA was similarly determined by both LC sugar and inutest to be at 1.0 +/- 0.2 and 1.1 +/- 0.2 mL/min (P= NS), respectively. In addition, GFR did not change when LC sugar plasma concentration gradually increased. CONCLUSION: Our results show that in both normal and pathophysiologic conditions, LC sugar is a good marker of GFR similar to the gold standard inutest.

Animals↗

PubMed1995

Sugar consumption and caries risk in schoolchildren with low caries experience.

This paper assesses the risk from sugar consumption in a population of school children with low caries experience. It relates eight different measures of sugar consumption to the occurrence of any DMFS increment, and, separately, to approximal and pit-and-fissure DMFS. The data are from a 3-yr longitudinal study of 429 children, initially aged 11-15, residing in non-fluoridated rural communities in Michigan, USA. All children completed at least three dietary interviews, were present for baseline and final dental examinations, and had a parent or guardian provide questionnaire information on residence history, use of fluoride and dental services, and family history. Results indicated that a higher proportion of total energy intake from sugars increased the probability of caries on all surfaces, and a higher total intake of sugars was also associated with total caries increment. No relationship, however, was found between DMFS increment and the frequency of eating high sugar foods. Each additional 5 g of daily sugars intake was associated with a 1% increase in the probability of developing caries, and those whose energy intake from sugars was 1 SD above the mean had 2.0 times the risk of developing approximal caries than did children whose energy intake from sugars was 1 SD below the mean.

Adolescent↗

PubMed2006

Sugar snack consumption in Ugandan schoolchildren: Validity and reliability of a food frequency questionnaire.

OBJECTIVES: This study assessed the reproducibility and relative validity of an eight-item self-administered food frequency questionnaire (FFQ) on intake of sugared snacks in Ugandan schoolchildren. A 5-day precoded food behaviour checklist (FBC) was used as validation criteria. Sociodemographic correlates of a sum frequency sugar score were explored. METHODS: The study was conducted in Kampala, Uganda, in 2004. Six hundred and fourteen schoolchildren (mean age 12.4 years) completed the FFQ on cakes/biscuits, chocolate, ice sticks, soft drinks, coffee, tea, sugared desserts and sweets/candies at school. They were examined clinically for dental caries. Forty students completed the FFQ twice, 1 week apart and 325 students completed the 5 day FBC at school. RESULTS: The mean decayed, missing and filled tooth index score was 0.98 (SD 1.6, range 0-15). Reproducibility scores (Cohen's kappa) for the sugar items ranged from 0.17 (ice sticks) to 0.55 (biscuits). No differences were seen between the average intakes at test and retest. Higher intake was reported in FFQ than in FBC across all sugar items. Crude agreement between students reporting intake at least 3-5 times a week/less than three times a week ranged from 50% to 55% (e.g. biscuits, chocolate) to 87% (tea). Spearman's correlation coefficients ranged from 0.14 (desserts) to 0.27 (sweets). anova revealed significant increase (P = 0.001) in the mean FBC sum scores by increasing quartiles of the FFQ sum scores. The average sum FFQ sugar scores were higher in girls than in boys and higher in older than in younger students. CONCLUSION: Fair reproducibility was established for the FFQ sugar items. The FFQ was acceptable in classifying individuals into broad categories of low and high sugar consumption.

Adolescent↗

PubMed1998

Membrane-bound glyceraldehyde-3-phosphate dehydrogenase and multiphasic erythrocyte sugar transport.

Net sugar import by human erythrocytes consists of ATP-modulated rapid and slow phases while sugar export consists of a single slow phase. We have proposed that this behaviour results from obligate substrate tunnelling from transporter to bulk cytosol through a complex containing high-affinity, low-capacity sugar binding sites (Cloherty, Sultzman, Zottola & Carruthers, 1995). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is known to compartmentalize ATP delivery to erythrocyte membrane ATPases and interact directly with the erythrocyte glucose transporter in vitro. The present study examines the possibility that GAPDH is an obligate component of the hypothesized sugar-binding complex. GAPDH remains associated with the erythrocyte membrane following cell lysis and remains associated with the cytoskeleton under conditions where more than 99% of the membrane glucose transport protein (GLUT1) is released by detergent (Triton X-100). GAPDH is released from erythrocyte membranes upon exposure to Mg.ATP or to NADH. ATP displacement of membrane-bound GAPDH is half-maximal at 200 microM ATP and appears to involve ATP interaction with multiple, co-operative sites. GAPDH interaction with purified tetrameric GLUT1 is saturable, co-operative and also inhibited by ATP. ATP inhibition of GAPDH binding to purified tetrameric GLUT1 is less effective than ATP inhibition of GAPDH binding to intact erythrocyte membranes. Removal of cellular GAPDH by exposing erythrocyte membranes to NADH prior to membrane resealing neither affects ATP modulation of sugar transport nor reduces biphasic net sugar uptake to a single phase. We conclude that ATP-sensitive GAPDH interaction with the cytoplasmic surface of erythrocyte membranes and GLUT1 is responsible neither for ATP modulation of sugar transport nor for multiphasic net sugar import by human red cells.

3-O-Methylglucose↗

PubMed1981

Sugar transport in giant axons of Loligo.

1. The transport of glucose and a number of other sugars has been investigated in the giant axons of Loligo forbesi. 2. Glucose and 2-deoxy-D-glucose are phosphorylated by squid axons, alpha-methyl-D-glucopyranoside and 3-O-methylglucose are not metabolized. All four sugars can diffuse freely in axoplasm. 3. Sugar uptake in squid axons is a passive, saturable process. The maximum rate of sugar uptake increases in the order 3-O-methylglucose less than 2-deoxy-D-glucose less than D-glucose. Competition between these sugars suggests a common uptake mechanism. 4. The uptake of D-glucose but not 3-O-methylglucose or 2-deoxy-D-glucose is reduced when the external Na concentration is lowered. 5. Glucose uptake is sensitive to temperature with a Q10 for saturated uptake of 1.9 between 14.5 and 5 degrees C. Uptake is unaffected by external pH in the range 5-10 but is reduced by cyanide (2 mM). 6. Glucose and 2-deoxy-D-glucose uptake and metabolism are increased by electrical stimulation. These effects are prevented by ouabain. The uptake of 3-O-methylglucose is unaffected by stimulation. 7. The maximum rate of 3-O-methylglucose efflux is higher than the maximum rate of uptake of the sugar suggesting that transport of this sugar is asymmetric. 8. 3-O-methylglucose efflux is reduced by external sugars with order of potency 3-O-methylglucose greater than 2-deoxy-D-glucose greater than D-glucose. These effects persist when the internal 3-O-methylglucose concentration is as high as 50 mM. 9. 3-O-methylglucose efflux is inhibited reversibly by cytochalasin B and phloridzin but irreversibly by phloretin. Efflux is reduced reversibly by cyanide (2 mM). 10. 3-O-methylglucose efflux is sensitive to temperature with a Q10 of 3.2 over the range 10-20 degrees C. Efflux is unaffected by external pH in the range 6-9 but is reduced reversibly by internal acidification.

Animals↗

PubMed1984

Effect of hyperglycaemia on sugar transport in the isolated mucosa of guinea-pig small intestine.

The effect of hyperglycaemia on sugar transport was studied by comparing transepithelial permeation and tissue content of 3-O-methyl-D-glucose (3-O-MG), beta-methyl-D-glucoside (beta-MDG) and D-glucose in isolated mucosae of guinea-pig jejunum mounted in a flux chamber. Sugars were administered either to the luminal or the blood side of mucosae prepared either from normal animals or those maintained in a hyperglycaemic state by I.V. glucose infusion for 12 h. In control animals, absorptive sugar fluxes increased in the order glucose greater than beta-MDG greater than 3-O-MG. Only beta-MDG was accumulated in the tissue beyond the medium concentration. Permeation of 3-O-MG and beta-MDG in the direction blood-to-lumen was mainly paracellular as indicated by the strict correlation with the simultaneous permeation of polyethylene glycol (mol. wt. 900). Luminal addition of 10(-3) M-phlorhizin increased permeation and decreased tissue content of beta-MDG and D-glucose when administered on the blood side, suggesting that these sugars are recaptured at the brush border even from vigorously mixed solutions. For flux coefficient calculation the preparation was regarded as a three-compartment system. With all three sugars, the influx coefficient was higher at the luminal, but lower at the basolateral membrane than the corresponding efflux coefficient. 3-O-MG displayed the highest basolateral influx coefficient of all three sugars, being even higher than its luminal influx coefficient. The luminal influx coefficient of beta-MDG was 22 times greater, and its basolateral efflux coefficient 2.5 times less than the corresponding values for 3-O-MG, resulting in cellular beta-MDG accumulation. D-Glucose was suited best for transepithelial transport, having a luminal influx coefficient only 1.6 times less, and a basolateral efflux coefficient almost 10 times greater than those for beta-MDG. Prolonged hyperglycaemia increased the lumen-to-blood permeation of all three sugars 1.3-2-fold. No significant differences in tissue content to control values were observed after 45 min (3-O-MG, D-glucose) or 90 min (beta-MDG) incubation. Therefore, flux coefficients increased by the same factors in luminal and basolateral membranes, i.e. 1.7, 1.3 and 1.7 for 3-O-MG, beta-MDG and D-glucose, respectively. These results indicate that changes in both the luminal and basolateral membranes play a role in the increase of sugar transport in hyperglycaemia and that a regulatory mechanism might exist between the transport systems located in both membranes.(ABSTRACT TRUNCATED AT 400 WORDS)

3-O-Methylglucose↗

PubMed2000

Role of leaf surface sugars in colonization of plants by bacterial epiphytes.

The relationship between nutrients leached onto the leaf surface and the colonization of plants by bacteria was studied by measuring both the abundance of simple sugars and the growth of Pseudomonas fluorescens on individual bean leaves. Data obtained in this study indicate that the population size of epiphytic bacteria on plants under environmentally favorable conditions is limited by the abundance of carbon sources on the leaf surface. Sugars were depleted during the course of bacterial colonization of the leaf surface. However, about 20% of readily utilizable sugar, such as glucose, present initially remained on fully colonized leaves. The amounts of sugars on a population of apparently identical individual bean leaves before and after microbial colonization exhibited a similar right-hand-skewed distribution and varied by about 25-fold from leaf to leaf. Total bacterial population sizes on inoculated leaves under conditions favorable for bacterial growth also varied by about 29-fold and exhibited a right-hand-skewed distribution. The amounts of sugars on leaves of different plant species were directly correlated with the maximum bacterial population sizes that could be attained on those species. The capacity of bacteria to deplete leaf surface sugars varied greatly among plant species. Plants capable of supporting high bacterial population sizes were proportionally more depleted of leaf surface nutrients than plants with low epiphytic populations. Even in species with a high epiphytic bacterial population, a substantial amount of sugar remained after bacterial colonization. It is hypothesized that residual sugars on colonized leaves may not be physically accessible to the bacteria due to limitations in wettability and/or diffusion of nutrients across the leaf surface.

Carbohydrates↗

PubMed1991

Sugar metabolism by fusobacteria: regulation of transport, phosphorylation, and polymer formation by Fusobacterium mortiferum ATCC 25557.

Strains of eight Fusobacterium species differed in the ability to use sugars as energy sources for growth. For Fusobacterium russii ATCC 25533, F. gonidiaformans ATCC 25563, and F. nucleatum ATCC 10953 (except for fructose), growth was marginal to poor on all of the sugars tested. Other species displayed reasonable growth on glucose, fructose, mannose, and galactose, and two strains of F. mortiferum (ATCC 25557 and ATCC 9817) grew well on six of the sugars tested, including sucrose and maltose. Glucose transport by resting cells of most of the species was dependent upon (or markedly stimulated by) the presence of a fermentable amino acid. By contrast, F. mortiferum cells rapidly accumulated glucose and other sugars in the absence of amino acids. Although these cells were constitutive for glucose uptake, accumulation of other sugars was specifically induced by growth of F. mortiferum on the appropriate sugar. Spectrophotometric analyses and in situ staining of anionic polyacrylamide gels showed that glucose and fructose (mannose) are phosphorylated by separate ATP-dependent kinases. Fructokinase was stable in air at 4 degrees C, but under these conditions, greater than 70% of the glucokinase activity was lost. After overnight dialysis of the extract, no glucokinase activity was detectable; however, 65% of the initial enzyme activity was retained by inclusion of 1 mM dithiothreitol in the dialysis buffer. Thin-section electron microscopy showed that cells of F. mortiferum produced various amounts of intracellular glycogen during growth on the following sugars (in decreasing order of formation): galactose greater than sucrose greater than glucose greater than mannose greater than fructose. Mechanisms for sugar transport regulation, phosphorylation, and polymer synthesis by F. mortiferum cells are proposed.

Biological Transport↗

PubMed1982

Mechanisms of appearance of the Pasteur effect in Saccharomyces cerevisiae: inactivation of sugar transport systems.

Saccharomyces cerevisiae does not show a noticeable Pasteur effect (activation of sugar catabolism by anaerobiosis) when growing with an excess of sugar and nitrogen source, but it does do so after exhaustion of the nitrogen source in the medium (resting state). We have found that this different behavior of growing and resting S. cerevisiae seems due to differences in the contribution of respiration to catabolism under both states. Growing S. cerevisiae respired only 3 to 20% of the catabolized sugar, depending on the sugar present; the remainder was fermented. In contrast, resting S. cerevisiae respired as much as 25 to 100% of the catabolized sugar. These results suggest that a shift to anaerobiosis would have much greater energetic consequences in resting than in growing S. cerevisiae. In resting S. cerevisiae anaerobiosis would strongly decrease the formation of ATP; as a consequence, various regulatory mechanisms would switch on, producing the observed increase of the rate of glycolysis. The greater significance that respiration reached in resting cells was not due to an increase of the respiratory capacity itself, but to a loss of fermentation which turned respiration into the main catabolic pathway. The main mechanism involved in the loss of fermentation observed during nitrogen starvation was a progressive inactivation of the sugar transport systems that reduced the rate of fermentation to less than 10% of the value observed in growing cells. Inactivation of the sugar transports seems a consequence of the turnover of the sugar carriers whose apparent half-lives were 2 to 7 h.

Ammonium Chloride↗

PubMed1984

Sodium-sugar coupling stoichiometry in chick intestinal cells.

Sodium-dependent sugar transport systems involve the function of membrane components that couple the transmembrane flow of Na+ to the concomitant flow of certain sugar molecules. The coupling stoichiometry between Na+ and sugar fluxes via these systems must be measured under conditions in which the membrane potential does not change due to the induction of transport or during the interval of flux measurement. This can be accomplished by utilizing gradients of highly permeant ions (NO-3 and K+ plus valinomycin) to create diffusion potentials of sufficient magnitude that the sugar-induced Na+ flux does not introduce an appreciable change in the imposed potential. Under these conditions, the coupling stoichiometry for chicken intestinal cells proves to be 2 Na+:1 sugar as reported earlier for studies performed in the absence of a membrane potential. When control of the potential is not maintained, a coupling ratio of 1:1 is observed. The stoichiometry does not change as a function of Na+ concentration, which suggests that carrier forms with only one Na+ bound do not contribute to the carrier-mediated Na+ or sugar fluxes. When no potential is present, the stoichiometry is modified by the level of intracellular Na+ and sugar in a manner indicative of a transport mechanism in which Na+ must dissociate from the "loaded" carrier at the inward facing membrane surface before the sugar molecule dissociates.

Adenosine Triphosphate↗

PubMed1990

Whole cell recording of sugar-induced currents in LLC-PK1 cells.

Gigaohm-seal whole cell recording techniques were used to monitor function of the Na(+)-coupled sugar transport system in LLC-PK1 cells. The currents coupled to sugar transport were identified as those that are induced by the presence of 10 mM alpha-methylglucoside (AMG) in either the extracellular or intracellular compartment and were inhibited by addition of 320-800 microM phlorizin to the extracellular bathing medium. The sugar-induced currents are small, 15-20 pA, but of the expected magnitude as determined from the known kinetic parameters for Na(+)-coupled sugar transport in LLC-PK1 cells. The phlorizin-sensitive currents are Na+ dependent and can be studied under conditions in which the net Na+ and sugar flux (and consequently the Na+ electrical current) is in either the inward or outward direction. The reversal potential of the sugar-induced currents measured under conditions with high Na+ and AMG concentrations inside the cell is close to values predicted from thermodynamic principles, assuming a coupling stoichiometry of 2 Na+: 1 sugar for the transport system. The reversal potential of the sugar-induced currents with high extracellular Na+ and AMG is not equal to the predicted value, but it is of the polarity expected for inward-imposed solute gradients. Reasons for the observed discrepancy between observed and calculated values are discussed.

Animals↗

PubMed1991

Effect of partial substitution of invert sugar for sucrose in combination with Duraphat treatment on caries development in preschool children: the Malmö Study.

The aim was to study the effect of substitution of invert sugar for sucrose, in combination with fluoride varnish (Duraphat) treatment twice a year, on caries development in preschool children. One hundred and eighty-seven 4-years-olds were divided randomly into four sugar groups: (1) sucrose (S), (2) sucrose-Duraphat (SD), (3) invert sugar (I), and (4) invert sugar-Duraphat (ID). All families were asked to buy beverages, biscuits, breakfast cereals, marmalade, ice cream, jam, ketchup, sweets and table sugar, totally 32 different food items, sweetened with invert sugar or sucrose. The substitution was, thus, restricted to a number of sugar-rich between-meal products. The study was carried out double-blind for 2 years. The children of those parents who did not want to participate in the sugar groups were divided randomly into one of the following two groups: (5) Duraphat (D), and control (C). Because of lack of cooperation, only 114 of the 187 children (61%) were considered to have completed the study. The mean caries increment, including initial lesions, was 3.86 dmfs in the combined groups S and SD (n = 63) and 3.10 dmfs in the combined groups I and ID (n = 51) during the 2 years (p = 0.34). The corresponding values for the 2nd year only were 1.84 and 0.67 dmfs, respectively (p = 0.09). The mean caries increment was 2.86 dmfs in group D (n = 113) and 4.10 dmfs (p = 0.08) in group C (n = 93). If initial caries lesions were excluded from the index, the difference between groups D and C was significant (p = 0.008).(ABSTRACT TRUNCATED AT 250 WORDS)

Cariogenic Agents↗

PubMed1984

Synthetic neoglycoproteins: a class of regents for detection of sugar-recognizing substances.

Specific interactions between proteins and sugars have recently been emphasized in many biological systems. To detect sugar-recognizing substances, known as lectin-like substances or endogenous lectins, we describe a method in which various sugars were covalently bound to a carrier protein such as albumin. This neoglycoprotein was stable at -20 degrees C for a period of 6 months. It was conjugated to various cytochemical markers (125I, fluorescein isothiocyanate, colloidal gold, or latex minibead). Detection of the marker then indicates the presence of the sugar-binding protein. Control experiments in the presence of unlabeled neoglycoprotein or specific sugar indicated the specificity of the reaction. This method was used to analyze the kinetics of binding for a mannose-recognition system in the mouse peritoneal macrophages. The data obtained were in agreement with those previously reported. The method can be used for detection of other sugar-recognizing systems as virtually every simple sugar can be bound to a carrier protein to produce these neoglycoproteins. Some of the consideration required for successful production of these reagents are discussed. These synthetic neoglycoproteins are useful in studying the distribution and kinetics of sugar-recognizing systems and may help to further our understanding of this rapidly developing area.

Animals↗

PubMed1997

The sugar specificity of Na+/glucose cotransporter from rat jejunum.

A cDNA for a Na+/glucose cotransporter was cloned from rat jejunum cDNA library. This transporter was expressed in Xenopus oocytes by injection of cRNA synthesized from the cDNA, and the transporter ability was electrophysiologically examined. The cotransporter had a very narrow sugar specificity. Only D-glucose, D-galactose, and some of their derivatives elicited significant electrical responses. These results of sugar specificity were compared with those of the H+/hexose cotransporter of Chlorella. Dose-response relationships of several sugars followed a simple Michaelis-Menten type of kinetics. Both Vm and Km were dependent on the sugars. Not only the affinity of sugars to the cotransporter but also the rate of conformational change of the cotransporter loaded with the sugar and Na+, which translocates them from outside to inside, possibly depends on the sugar structure. The rate-limiting step of the transportation may be the conformational change, i.e., isomerization, of the cotransporter that translocates both the sugar and Na+ from outside to inside.

Animals↗

PubMed2001

Structures of the N-linked sugar chains in PAS-7 glycoprotein sharing the same protein core with PAS-6 glycoprotein from the bovine milk fat globule membrane.

Glycoproteins PAS-6 (50 kDa) and -7 (47 kDa) from the bovine milk fat globule membrane share a common protein core but differ in their carbohydrate moiety. We here analyzed and proposed the structures of the N-linked sugar chains of PAS-7. The N-linked sugar chains were liberated from PAS-7 by hydrazinolysis and, after modifying the reducing ends with 2-aminopyridine (PA), were separated into one neutral (7N, 55%) and two acidic (7M, mono-, 43%; 7D, di-, 2%) sugar chain groups. The latter were converted into neutral groups (7MN and 7DN) by sialidase digestion. 7N was finally separated into 5 chains (7N1A, 7N1B-1, 7N1B-2, 7N2A, and 7N2B), and 7MN and 7DN were separated into 3 (7MN1, 7MN2, and 7MN3) and 2 (7DN1 and 7DN2) chains, respectively. The structure of each of these PA-neutral sugar chains was determined by sugar analysis, sequential exoglycosidase digestion, partial acetolysis, and 1H-NMR spectroscopy. The results show that the 10 sugar chains were of the biantennary complex type with and without fucose. The structure of 7N2A, one of the major sugar chains, was proposed as; [structure: see text] A structural comparison between PAS-6 and -7 indicated that, although they shared the same protein core, their sugar moiety was markedly different, involving the existence of a different pathway during the post-transcriptional modification.

Animals↗

PubMed2005

Confronting the 'sugar daddy' stereotype: age and economic asymmetries and risky sexual behavior in urban Kenya.

CONTEXT: "Sugar daddy" relationships, which are characterized by large age and economic asymmetries between partners, are believed to be a major factor in the spread of HIV in Sub-Saharan Africa. Information is needed about sugar daddy partnerships-and about age and economic asymmetries more generally-to determine how common they are and whether they are related to unsafe sexual behavior. METHODS: The sample comprised 1,052 men aged 21-45 who were surveyed in Kisumu, Kenya, in 2001. Data on these men and their 1,614 recent non-marital partnerships were analyzed to calculate the prevalence of sugar daddies and sugar daddy relationships, as well as a range of age and economic disparities within non-marital partnerships. Logistic regression models were constructed to assess relationships between condom use at last sexual intercourse and various measures of age and economic asymmetry. RESULTS: The mean age difference between non-marital sexual partners was 5.5 years, and 47% of men's female partners were adolescents. Fourteen percent of partnerships involved an age difference of at least 10 years, and 23% involved more than the mean amount of male-to-female material assistance. Men who reported at least one partnership with both these characteristics were defined as sugar daddies and made up 5% of the sample; sugar daddy relationships accounted for 4% of partnerships. Sugar daddy partnerships and the largest age and economic asymmetries we constructed were associated with decreased odds of condom use. CONCLUSIONS: Although sugar daddy relationships are not as pervasive as generally assumed, age and economic asymmetries in non-marital partnerships are relatively common. All these types of asymmetries are associated with nonuse of condoms. Increasing women's power within asymmetric sexual relationships could improve their ability to negotiate safer sexual behaviors, such as condom use.

Adolescent↗