Barry J. Blackburn

Metabolites of alveolarEchinococcus as determined by [31P]- and [1H]-nuclear magnetic resonance spectroscopy

Abstract[31P]-Nuclear magnetic resonance (NMR) in vivo spectra ofEchinococcus multilocularis cysts growing subcutaneously inMeriones unguiculatus showed prominent signals due to phosphomonoesters (PME), phosphodiesters (PDE), inorganic phosphate (Pi) and the α, β and γ phosphate groups of adenosine triphosphate (ATP). The internal pH of the parasite cysts was 6.7–6.8. The31P spectra of extracts of these subcutaneous cysts showed peaks identified as glucose-6-phosphate (Glu-6-P), glycerol-3-phosphate (Gly-3-P), phosphorylethanolamine (PE), adenosine-5′-monophosphate (5′-AMP), nicotinamide adenine dinucleotide phosphate (NADP), phosphorylcholine (PC), Pi, glycerolphosphorylethanolamine (GPE), glycerolphosphorylcholine (GPC), phosphoenolpyruvate (PEP), adenosine diphosphate (ADP), ATP and diphosphodiesters (DPDE). These metabolites were also detected at comparable concentrations in the extracts of intraperitoneally grown cysts. In addition, significantly more phosphocreatine (PCr), probably of host origin, was detected in the subcutaneous cysts than in the intraperitoneal cysts. [1H]-NMR spectra of cyst extracts revealed that parasites grown in the abdominal cavity contained significantly less glucose but significantly more succinate, acetate, alanine and β-hydroxybutyrate. Glycogen, creatine, glycine, taurine, betaine, cholines and lactate were present at similar concentrations in cyst material from both locations.

Metabolism of [3-13C]-pyruvate by cysticerci of Taenia crassiceps

Abstract Carbon-13 decoupled 1H spin-echo nuclear magnetic resonance (NMR) spectra, with and without 13C population inversion, of extracts of Taenia crassiceps cysticerci incubated in media containing [3-13C]-pyruvate showed 13C enrichment in alanine, lactate, acetate, succinate, and citrate. Labeling in the latter three metabolites provides substantial evidence that the malic enzyme reaction in this cestode also functions in the direction opposite to that in which it is normally portrayed. The direct passage of pyruvate from the cytosol to the mitochondrion is suggested by the greater percentage of 13C detected in acetate relative to succinate.

A NMR study of parasitized Tenebrio molitor and Hymenolepis diminuta cysticercoids

In vivo NMR spectra of uninfected and Hymenolepis diminuta-infected Tenebrio molitor fed D-(1-13C)glucose showed that infected beetles of both sexes had a significantly higher ratio for (glycogen C1/lipid (CH2)n) than the corresponding controls. Quantitative metabolic profiles and the per cent 13C-label in metabolites, based on NMR of perchloric acid extracts, are presented for control and infected beetles fed D-(1-13C)glucose and for H. diminuta cysticercoids. Female beetles, both control and infected, contained more glycogen than their male counterparts and infected beetles of both sexes possessed less glycerophos-phocholine, but more glycogen and a higher percentage label in glucose and trehalose than their respective controls. Label was also incorporated into glycogen, succinate, acetate, alanine and lactate. Extracts of cysticercoids from beetles fed D-(1-13C)glucose contained the following labelled compounds, in order of decreasing per cent 13C label: glucose, trehalose, alanine, succinate, lactate, glycogen and acetate. In vitro cultivation experiments, employing D-(1-13C)glucose, revealed that trehalose found in cysticercoids was of parasite, and not beetle, origin.

Metabolic alterations in organs of Meriones unguiculatus infected with Echinococcus multilocularis

1. 1H-NMR spectra of liver, spleen and kidney extracts from Meriones unguiculatus infected with Echinococcus multilocularis showed decreased levels of glucose. In addition, the liver extracts were severely glycogen-depleted. 2. Both livers and spleens contained less glycine, taurine and acetate. Spleens also had fewer cholines and less lactate but more betaine and alanine. 3. In the kidneys, elevated concentrations of succinate, acetate and lactate were found.

Proton nuclear magnetic resonance analysis of liver metabolites from mice infected with Mesocestoides vogae

Proton NMR spectra of liver extracts from mice infected with Mesocestoides vogae for 24 or 133 days showed differences in the concentrations of liver metabolites when compared to those of normal liver. Moderately infected livers (24 d.p.i.) had significantly less glucose and significantly more glycine, cholines, alanine and lactate than uninfected controls. Similar changes in the concentrations of these metabolites were also found in mice with heavily infected livers (133 d.p.i.), and, in addition, there was significantly more succinate in this group than in the other 2 groups. Furthermore, the heavily infected livers contained more taurine and less acetate than the controls. Tetrathyridia extracts were rich in glycogen and contained high levels of betaine.

A nuclear magnetic resonance study of the D-[13C6] glucose metabolism of Mesocestoides corti tetrathyridia in the absence and presence of monensin

Abstract Novak M. and Blackburn B. J. 1988. A nuclear magnetic resonance study of the d -[ 13 C 6 ]glucose metabolism of Mesocestoides corti tetrathyridia in the absence and presence of monensin. International Journal for Parasitology 18 : 1029–1033. The effect of monensin on the glucose metabolism of Mesocestoides corti tetrathyridia was studied using 1 H and 13 C nuclear magnetic resonance (n.m.r.) spectroscopy. Signals due to lactate, succinate, acetate and alanine were identified in the spectra of the excretory products of tetrathyridia fed d -[ 13 C 6 ]glucose in vitro for 120 min. Monensin, at a concentration of 10 μ m , inhibited glucose uptake across the brush border of the tetrathyridia, as indicated by a higher level of labelled hexose and lower levels of metabolic end products in ionophore-containing culture medium. The possible action of monensin on the glucose transport mechanism is discussed.

NMR study of lipid changes in organs of jirds infected with Echinococcus multilocularis

Abstract Proton NMR spectroscopy was used to investigate changes in composition of lipids in the liver, kidneys and adrenal glands of Meriones unguiculatus infected with Echinococcus multilocularis. It was found that all three organs of infected animals had less total glycerophospholipid and CH2 in the fatty acid (FA) component CHCH(CH2CHCH)n than the corresponding organs of uninfected animals. The concentrations of other lipids in these organs were variable in their response to infection. The livers of infected jirds had lower concentrations of phosphatidylcholine (PTC), phosphatidylinositol, cholesterol (CTL) and the FA component CH2CH2COO, but more phosphatidylethanolamine (PTE). Kidneys of infected animals had less PTC, PTE and arachidonic acid. The adrenal glands, which were most affected by E. multilocularis infection, had lower concentrations of PTE, CTL, total FA, triacylglycerol, linoleic acid, and the FA components CH2CH2COO, CH2COO, CH2 in (CH2)n, CHCH and CH2CHCH.

Comparison of the effects of imidazo[1,2-a]pyridine-2-carbamates and benzimidazole-2-carbamates on the development ofHymenolepis nana inTribolium confusum

The anthelmintic properties of several imidazo[1,2-a]pyridine carbamates and benzimidazole carbamates againstHymenolepis nana are compared. The results of this study, coupled with previous work, indicate that methyl 6-(trichloroethenyl)-imidazo[1,2-a]pyridine-2-carbamate has the potential of being a broad spectrum anthelmintic, effective against both nematodes and cestodes.

A nuclear magnetic resonance study of the glucose metabolism of Hymenolepis diminuta exposed to histamine and serotonin in vitro

The direct effects of the inflammatory mediators, histamine (HI) and serotonin (SE), on the glucose metabolism of Hymenolepis diminuta in vitro were studied by analyzing the excretory products from culture media, containing D-1-13C-glucose and various concentrations of HI and/or SE, by 1H-nuclear magnetic resonance (n.m.r.) spectroscopy. The results revealed that HI markedly accelerated the glycolysis process by increasing the amount of lactate production. The increased glycolytic activity was reflected in a concentration-dependent increase in glucose uptake. Excretion of acetate was also stimulated by HI. A low concentration of SE significantly increased succinate, acetate and lactate excretions, whereas a high concentration had little effect on lactate production and significantly decreased succinate and acetate excretions. A combination of HI and SE treatment at a low concentration had no significant effect, but at a high concentration showed an additive effect, with an increase in lactate production, a decrease in succinate production and an increase in glucose uptake. Thus this work confirms that HI and SE directly influence, albeit differently, energy metabolism of the tapeworm H. diminuta.

Effect of Echinococcus multilocularis on the origin of acetyl-CoA entering the tricarboxylic acid cycle in host liver

Carbon-13 nuclear magnetic resonance (NMR) spectroscopy was employed to investigate alterations in hepatic carbohydrate metabolism in Meriones unguiculatus infected with Echinococcus multilocularis. Following portal vein injections of an equimolar mixture of [1,2-13C2]acetate and [3-13C]lactate, perchloric acid extracts of the livers were prepared and NMR spectra obtained. Isotopomer analysis using glutamate resonances in these spectra showed that the relative contributions of endogenous and exogenous substrates to the acetyl-CoA entering the tricarboxylic acid cycle differed significantly between infected and control groups. The mole fraction of acetyl-CoA that was derived from endogenous, unlabelled sources (F(U)) was 0.50 +/- 0.10 in controls compared to 0.34 +/- 0.04 in infected animals. However, the fraction of acetyl-CoA derived from [3-13C]lactate (FLL) was larger in livers of infected animals than those from controls with values of 0.27 +/- 0.04 and 0.18 +/- 0.04, respectively. Similarly, the fraction of acetyl-CoA derived from [1,2-13C2]acetate (FLA) was larger in livers of infected animals compared to those in controls; the fractions were 0.38 +/- 0.01 and 0.32 +/- 0.07, respectively. The ratio of FLA:FLL was significantly smaller in the infected group with a value of 1.42 +/- 0.18 compared to 1.74 +/- 0.09 for the controls. These results indicate that alveolar hydatid disease has a pronounced effect on the partitioning of substrates within the pathways of carbohydrate metabolism in the host liver.