The purpose of this study was to examine the effects of pre-exercise carbohydrate feeding on repeated bouts of anaerobic exercise in pre- and early-pubertal boys. Eleven boys, (10.2 ± 1.3 yrs) maturation stage I and II according to Tanner participated in this study. Peak (PP) and mean power (MP) were examined using 4 repeated Wingate Anaerobic Tests (WAnT) bouts. Two double-blind, randomized trials were performed; a carbohydrate (CHO) and placebo (PL) trial. A two-way (trial by time) ANOVA was used to analyze PP, MP, blood glucose, lactate, heart rate (HR) and ratings of perceived exertion (RPE). Statistical significance was set at p < 0.05. PP and MP were not significantly different across trials. Glucose was significantly higher after CHO consumption, but post-exercise responses did not vary between trials. There was no significant trial or time effect and no interaction effect for HR. There was a significant time effect for lactate and RPE. The results suggest that pre-exercise CHO feeding does not enhance anaerobic exercise performance in children, a finding that is similar to outcomes involving adults. / School of Physical Education, Sport, and Exercise Science

Six runners (V02 max=68.2 ± 3.4 ml/kg/min) were studied on three separate occasions during a 30 min treadmill run at 70% V02 max. On each occasion, the subjects ingested either 75g of glucose (trial G), fructose (trial F) or a sweetened placebo (trial C). No differences were observed between any of the trials for oxygen uptake, heart rate or perceived exertion. Serum glucose levels were elevated as a result of the glucose feeding (P<0.05) reaching peak levels at 30 min post-feeding. With the onset of exercise, glucose levels dropped to a low of 5.89 ± 0.99 mmol/l at 15 min of exercise in trial G. Serum glucose concentrations in trials F and C averaged 6.21 ± 0.31 mmol/l and 5.95 ± 0.23 mmol/l over all the time points, respectively, and were not different (p>0.05). Muscle glycogen utilization in the first 15 min of exercise was similar in trial C (18.8 ± 1.9 mmol/kg), trial F (16.3 ± 4.1 mmol/kg) and trial G (18.8 ± 9.1 mmol/kg), and total glycogen use was also similar in trial C (20.7 ± 5.3 mmol/kg), trial F (35.4 ±6.3 mmol/kg) and trial G (25.6 ± mmol/kg). These data suggest that pre-exercise feedings of fructose or glucose do not affect the rate of muscle glycogen utilization during 30 min of treadmill running in well-trained runners.

This study compared the exercise responses of a waxy starch (WS), resistant starch (RS), glucose (GL) and an artificially-sweetened placebo (PL) ingested prior to exercise. Ten college-age, male competitive cyclists completed four experimental protocols consisting of a 30 min isokinetic, self-paced performance ride preceded by 90 min of constant load cycling at 66% VO2max. Thirty min prior to exercise, they ingested 1 g•kg-1 body weight of GL, WS, RS, or PL. A familiarization trial was first conducted to eliminate a potential order effect. An order effect was evidenced by lower (p<0.05) work rates during the performance ride of the first trial (390 ± 26.1 kJ) than the other four trials. No order effect was observed for the remainder of the experimental treatments which were performed in a single-blind, randomized fashion. At rest, GL elicited greater (P<0.05) serum glucose and insulin responses than all other trials. During exercise, however, serum glucose and insulin responses were similar among trials. Blood C-peptide and glucagon responses were also similar among trials. The mean total carbohydrate oxidation rates (CHOox) were higher (p<0.05) during the GL, WS, and RS trials (2.59 ± 0.13, 2.49 ± 0.10, and 2.71 ± 0.15 g•min-1, respectively) compared to PL (2.35 ± 0.12 g•min-1). Subjects were able to complete more work (p<0.05) during the performance ride when they ingested GL (434 ± 25.2 kJ) or WS (428 ± 22.5 kJ) compared to PL (403 ± 35.1 kJ). They also tended to produce more work with RS ingestion (418 ± 31.4 kJ), although this did not reach statistical significance (p<0.09). These results indicate that pre-exercise CHO ingestion in the form of starch or glucose maintained higher rates of total carbohydrate oxidation during exercise and provided an ergogenic benefit during self-paced cycling. / Human Performance Laboratory

Inhibiting the formation of ice is an essential process commercially, industrially, and medically. Compounds that work to stop the formation of ice have historically possessed drawbacks such as toxicity or prohibitively high active concentrations. One class of molecules, ice recrystallization inhibitors, work to reduce the damage caused by the combination of small ice crystals into larger ones. Recent advances made by the Ben lab have identified small molecule carbohydrate analogues that are highly active in the field of ice recrystallization and have potential in the cryopreservation of living tissue. A similar class of molecules, kinetic hydrate inhibitors, work to prevent the formation of another type of ice – gas hydrate. Gas hydrates are formed by the encapsulation of a molecule of a hydrocarbon inside a growing ice crystal. These compounds become problematic in high pressure and low temperature areas where methane is present - such as an oil pipeline. A recent study has highlighted the effects of antifreeze glycoprotein, a biological ice recrystallization inhibitor, in the inhibition of methane clathrates. Connecting these two fields through the synthesis and testing of small molecule ice recrystallization inhibitors in the inhibition of methane hydrates is unprecedented and may lead to a novel class of compounds.

Lipopolysaccharide (LPS), one of the main components of Gram-negative bacterial cell walls, is a potent endotoxin. Structures of the unique protective monoclonal antibody (mAb) WN1 222-5 in complex with Escherichia coli R2 and R4 LPS core regions show that recognition occurs in a manner similar to the innate immune receptor Toll-like receptor 4 (TLR4). Inner core LPS is shown to exist in a conserved epitope with multiple intramolecular interactions that allows the conserved epitope to bind strongly to mAb WN1 222-5. The structure of mAb FDP4, directed against truncated E. coli J-5 LPS, shows a deep pocket combining site specific for a terminal epitope that does not allow room for wild type (wt) LPS. Research into these anti-LPS binding mAbs opens up new avenues for potential septic shock therapy. The explosion of new techniques and bright x-ray sources in the 80’s and 90’s led to rapid advancement of protein x-ray crystallography; however, structure determination on some of the most important problems is now stalled due to the general inability to grow crystals of sufficient size. Recent advances in electron microscopy (EM) technology has led to improved beam characteristics, which has allowed the initiation of research to develop EM as a viable alternative to x-ray crystallography. In this research, method development using standard equipment to explore potential avenues for analysing three-dimensional protein crystals via EM has been explored. / Graduate / 0982 / 0487 / 0537 / kgomery@uvic.ca

Graduation date: 1984

SUMMARY The moenomycin-type compounds are known to inhibit selectively the enzyme penicillin binding protein 1b (PBP 1b) that catalyses the transglycosylation reaction in the biosynthesis of bacterial cell wall peptidoglycan. The moenomycins (see moenomycin A12) have been shown to interfere with this biosynthetic step interacting with the enzyme(s). The moenomycins do not induce resistance readily. A weak point in this respect may, however, be the phosphate bond to unit F. Its cleavage by a yet poorly characterized enzyme is the only enzymatic degradation reaction of the moenomycins that is known to-date. With this in mind we started a programme aimed at synthesizing trisaccharide analogues of moenomycin A12 in which the phosphate oxygen at C-1 of unit F is replaced by a CH2 group. It seemed important to retain all other functional groups in ring F as present in moenomycin since they are known to be of major importance as far as antibiotic activity is concerned. It appeared that the commercially available and cheap b-D-galactose-pentaacetate 30 would be an interesting starting material for this synthesis. In this work, the synthesis began with the introduction of the C-glycoside appendage at position 1 according to Giannis et al., thus forming the allyl C-galactopyranoside 34, a substance that represents the first C-glycosyl backbone for the synthesis of the glycosyl acceptors. The total synthesis of the glycosyl acceptors is shown in Scheme 6.1. We wanted to convert the C-allyl glycoside 34 into its propenyl analogue. Attempts to achieve this with singlet oxygen and palladium-mediated reaction proved fruitless. On the other hand, ene reaction of 34 with 4-phenyltriazolin-3,5-dione in CH2Cl2 provided 56 in 83 % yield. Ozonolysis of this alkene (-70 °C, MeOH-CH2Cl2) and subsequent quenching with dimethyl sulfide, followed by reduction of the crude aldehyde with sodium acetoxyborohydride (prepared from NaBH4 and AcOH in THF) furnished the primary alcohol 35 (85 %). This alcohol was converted into the mesylate 60 (60 %), and this in turn into the bromide 61 (80 %) by heating it at 80 °C with tetrabutylammonium bromide in toluene. The acetate groups were hydrolysed using Zemplén conditions to furnish 62 quantitatively. The primary hydroxyl group in 62 was protected as a tBuPh2Si ether 63 (85 %) on reaction with TBDPSCl in DMF at 0 °C, and as a tBuMe2Si ether 94 (87 %) on reaction with TBDMSCl in DMF at 0 °C in the presence of imidazole. PTScatalysed isopropylidenation of the 3,4-diols 63 and 94 with 2,2-dimethoxypropane in dry acetone gave the 3,4-O-acetonide derivatives 53 (88 %) and 95 (90 %), respectively. On the other hand, the glycosyl acceptor 53 was converted into the glycosyl acceptor 92. The free hydroxyl group in compound 53 was protected as an acetate group on reaction with acetic anhydride in pyridine in the presence of DMAP giving 89 (88 %). The silyl ether in 89 was cleaved with a molar solution of TBAF in THF affording compound 90 in 87 % yield. The free hydroxyl group in 90 was then subjected to an oxidation using the TEMPO method affording the aldehyde which was in turn oxidised with sodium chlorite to the corresponding acid. The acid was converted to the amide 91, making use of Staab's method, in which the acid was activated with CDI in dichloromethane to give the imidazolide, which upon reaction with ammonia furnished the amide 91 in an overall yield of 95 %. The required glycosyl acceptor 92 was obtained in quantitative yield by cleavage of the ester bond at position 5 under Zemplén conditions. Disaccharide formation was achieved employing the Jacquinet and Blatter method, which involves the use of glycosyl donor 67 and TMSOTf. No reaction was observed between this donor and acceptor 92, which may reflect the low nucleophilicity of the acceptor. On the contrary, glycosylation with acceptor 53 gave 68 (79 %). Deprotection of the silyl group in the disaccharide 68 was easily accomplished on treatment with a molar solution of TBAF in THF at RT affording 71 (89 %). Synthesis of the uronamide 72 was achieved after three major steps, in an overall yield of 98 %. Oxidation of the primary hydroxyl group in unit F to the corresponding aldehyde was accomplished with sodium hypochlorite and TEMPO. Oxidation of the crude aldehyde to the carboxylic acid with sodium chlorite followed by amide formation according to Staab gave 72. Removal of the isopropylidene group from 72 with trifluoroacetic acid (TFA) at RT furnished the diol 73 (89 %). Introduction of the carbamoyl group at C-4F position was achieved in two steps. Conversion of the diol 73 into the cyclic carbonate 76 with CDI in CH2Cl2 (84 %) and subsequent ring opening of this carbonate by bubbling a stream of gaseous ammonia into the CH2Cl2 solution at 0 °C gave 74 (62 %) as well as its isomer 77 (21 %). Dehalogenation of the N-trichloroacetyl group was intensively studied, but interactions of other functional groups in the studied substances could not be avoided. The base-labile carbonate in 76 and the carbamoyl group in urethane 74 were cleaved under the reaction conditions. Hydrolysis of 76 with 0.5 M LiOH in MeOH-THF (1:1) followed by acetylation gave 80 (73 %), while its reduction with NaBH4 in ethanol followed by acetylation gave 82 (60 °C, 85 %; RT, 83 %). On the other hand, reduction of 74 with NaBH4 in ethanol at 60 °C followed by acetylation gave 82 (78 %), while performing the reduction step at 5 °C (THF-MeOH 4:1) or at RT (ethanol or isopropanol) gave 80 in an average yield of 65 %. In a non reproducible reaction (NaBH4, EtOH, RT, then Ac2O, pyridine, RT), the desired compound 83 (42 %) was obtained accompanied by 82 (46 %) The reaction between the N-trichloroacetyl group and NaBH3CN was also fruitless. The phosphonate grouping was installed making use of Arbuzov reaction furnishing 85 (70 %). Trisaccharides could not be obtained from the oxazoline donor 42 (prepared from chitobiose octaacetate 86) through its reaction with acceptor 53. There was also no coupling product between the recently synthesized donor 88 and the acceptor 92. However, in this work, trisaccharide formation was achieved through the glycosylation reaction of donor 88 and acceptor 95 in 50 % yield (-30 °C, 1,2-dichloroethane, 3 Å, TMSOTf-TEA). Selective deprotection of the TBDMS group in compound 96 was accomplished at -10 °C with 1 eq of a molar solution of TBAF in THF. The free hydroxyl group of 97 was subjected to an oxidation using the TEMPO method affording the aldehyde. After oxidation of the aldehyde with sodium chlorite, the resulting carboxylic acid was converted according to Staab's method into the amide 93 in an overall yield of 95 % (based on 96). There were difficulties in converting the N-phthalimido group in 93 to the N-acetyl group which is necessary for biological activity of moenomycin-type compounds, since the reactions were accompanied by elimination of HBr. In conclusion, the synthetic methods employed in this work allow to prepare the di- and trisaccharides C-phosphonate analogues of moenomycin A12. / Synthese von Phosphonat-Analoga des Antibiotikums Moenomycin A12 Universität Leipzig, Dissertation Diese Arbeit enthält 130 Seiten, 73 Abbildungen, 1 Tabelle, 156 Literaturangaben Referat: Im Rahmen der vorliegenden Arbeit wurden C-Glycosid-Di- und Trisaccharid-Bausteine des Antibiotikums Moenomycin A12 ausgehend von b-D-Galactose-pentaacetat hergestellt. Das Ausgangmaterial wurde in D-Galactoheptonamid übergeführt. Die Einheit F des Disaccharidbausteins hat alle Substituenten, die die Einheit F des Moenomycins A12 hat. Der ausgearbeitete Syntheseweg sollte zur Synthese anderer Analoga geeignet sein.

Knowledge about the structure, conformation and dynamics of carbohydrates is important in our understanding of the way carbohydrates function in biological systems, for example in intermolecular signaling and recognition. This thesis is a summary of five papers studying these properties in carbohydrate-containing molecules with NMR spectroscopy and molecular dynamics simulations. In paper I, the ring-conformations of the six-membered rings of two carbaiduronic analogs were investigated. These carbasugars could potentially be used as hydrolytically stable mimics of iduronic acid in drugs. The study showed that the equilibrium is entirely shifted towards the 4C1 conformation. Paper II is an investigation of the conformational flexibility and dynamics of two (1→6)-linked disaccharides related to an oligosaccharide epitope expressed on malignant tumor cells. In paper III, the conformational space of the glycosidic linkage of an alfa-(1→2) linked mannose disaccharide present in N- and O-linked glycoproteins, was studied. A maximum entropy analysis using different priors as background information was used and four new Karplus equations for 3JC,C and 3JC,H coupling constants, related to the glycosidic linkage, were presented. Paper IV describes a structural elucidation of the exopolysaccharide (EPS) produced by Streptococcus thermophilus ST1, a major dairy starter used in yoghurt and cheese production. The EPS contains a hexasaccharide repeating unit of d-galactose and d-glucose residues, which is a new EPS structure of the S. thermophilus species. In paper V, the dynamics of three generations of glycodendrimers were investigated by NMR diffusion and 13C NMR relaxation studies. Three different correlations times were identified, one global correlation time describing the rotation of the dendrimer as a whole, one local correlation time describing the reorientation of the C-H vectors, and one correlation time describing the pulsation of a dendrimer branch.

This thesis investigated the role of carbohydrates in the dietary choices of ruminants with an emphasis on dairy cows. The first two experiments investigated the ability of sheep to select between feeds based on their carbohydrate degradability. A further two indoor experiments using dairy cows were designed to establish whether post-ingestive feedback from rumen fluid propionic acid concentration influenced preference. The final experiment examined the potential of ryegrass bred for high water soluble carbohydrate (WSC) concentrations to increase the long-term (9 days) preferences and intake of grazing dairy cows. / Constraints to intake imposed by offering sheep access to only one feed were overcome by offering a choice between two feeds simultaneously. Within each choice, sheep generally selected the more slowly degradable option. However, when overall NDF intake could be maintained at approximately 800g/day, the rapidly degraded feed was preferred. / Dairy cows were able to form associations between flavour and postingestive feedback from rumen propionic acid concentration. Although a dose-dependent response was not observed between the concentration of ruminal propionic acid infusion and preference intensity, there was a correlation between ruminal propionic acid concentration and energy status of the cow. In the subsequent experiment, the comparative effect of propionate supplied in the form of salt (instead of acid) on food preference was confounded by a flavour bias. / Diurnal WSC monitoring of perennial ryegrass cultivars bred in the U.K. for 'typical' and 'high' WSC concentrations, expressed similar concentrations at different times of the day and year when grown in northern Victoria. Consequently, in a test of preference between the cultivars, cows showed only slight preference that was not based on WSC concentration. In other choices between adjacent monocultures, cows selected a mixed diet of 62% white clover and 38% ryegrass. / It was concluded that the ideal diet from the animals' perspective is influenced by the rumen propionic acid concentration and the energy status of the animal. Further, an important priority for the ruminant is to maintain an adequate supply of structural carbohydrates to the rumen. Further work is needed to identify the benefits of feeding pasture with higher WSC, but this might be a difficult objective under Australian field conditions until plant material becomes available that more reliably expresses high WSC.

Thesis (Ph.D.)--McMaster University (Canada), 1992. / Source: Dissertation Abstracts International, Volume: 54-08, Section: B, page: 4119. Adviser: D. B. MacLean.