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.

Changes in hepatic lipids of mice infected with cysticerci of Taenia crassiceps.

Nuclear magnetic resonance (NMR) spectroscopy was employed to investigate the effect of infection with Taenia crassiceps cysticerci on the lipid profile of mouse liver. Chloroform/methanol extracts of livers from infected mice showed lower concentrations of phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, total glycerophospholipid, triacylglycerol, total fatty acid (FA) and all measured FA components than those from controls. Furthermore, the ratios obtained on dividing concentrations of the FA components by that of total FA demonstrate that the concentration decreases caused by infection are less for polyunsaturated fatty acids (FAs) than for other FAs. Extracts of T. crassiceps displayed a similar lipid profile to that of host liver but contained a lower lipid content and a shorter average FA chain length.

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

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.

Alteration in brain metabolites of jirds infected with alveolar Echinococcus.

The Meriones unguiculatus-Echinococcus multilocularis host-parasite system was used to evaluate changes in metabolite levels in the brain of the infected host. Nuclear magnetic resonance analysis of perchloric acid extracts of the entire brain of jirds revealed that infection caused a change in the concentration of several metabolites, especially those that serve as amino acidergic neurotransmitters in this organ. The concentrations of the neuroexcitatory compounds glutamate and aspartate and the neuroinhibitory compounds glycine and taurine were significantly reduced. Those of 2 other amino acids, glutamine and alanine, were also decreased. In addition, concentrations of glycerophosphocholine and phosphocholine were also lower, whereas those of phosphocreatine and N-acetylaspartate were elevated.

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.

Phosphate metabolites of Tenebrio molitor (Coleoptera: tenebrionidae) infected with metacestodes of Hymenolepis diminuta.

In vivo phosphorus-31 nuclear magnetic resonance (31P NMR) spectra and those of extracts of Tenebrio molitor L. infected with metacestodes of Hymenolepis diminuta R. showed modifications in the amounts of phosphorous-containing metabolites when compared with those of uninfected beetles. Infected females were more affected than infected males, having significantly more glucose-6-phosphate (Glu-6-P), glycerol-3-phosphate (Gly-3-P), and phosphorylethanolamine (PE), but less inorganic orthophosphate (Pi), glycerophosphorylethanolamine (GPE), gylcerolphosphorylcholine (GPC), phosphoarginine (PAr), and adenosine diphosphate (ADP). Infected males had more Glu-6-P and PE, but less Pi, GPE, and GPC. These changes directly reflected the phosphorylation potential of infected hosts, which increased approximately 100% and 50% in infected females and males, respectively.

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.

1H NMR study of metabolic alterations in the small intestine of rats infected with Hymenolepis diminuta.

1H NMR spectra of the duodenum, jejunum and ileum tissues of the small intestine of a rat showed metabolic gradients. 2. The concentrations of metabolites in these gut regions were altered by the presence of the tapeworm Hymenolepis diminuta. 3. In the infected duodenum there was significantly less glycogen, glucose and phosphocreatine/creatine, but significantly more lactate than in the corresponding controls. 4. Infected jejunum contained significantly less betaine but significantly more succinate, alanine and lactate. 5. Infected ileum had significantly less glycogen and taurine but significantly more alanine and lactate.

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.

Phosphorus metabolites of liver from mice infected with Hymenolepis microstoma.

31P NMR in vivo spectra of mouse livers infected with Hymenolepis microstoma for 130 or 265 days showed modifications in phosphorus-containing metabolite ratios when compared to those of normal liver. After 130 days of infection the metabolite ratio of inorganic phosphate (Pi)/beta ATP significantly increased whereas that of phosphocreatine (PCr)/beta ATP significantly decreased. In older, 265 day infections, the increase in Pi/beta ATP and decrease in PCr/beta ATP persisted. Changes in the group infected for 130 days were accompanied by lowered pH. Analysis of liver extracts from mice with 130-day-old. H. microstoma revealed significantly lower concentrations of Pi, ATP and ADP compounds. In those from mice infected for 265 days the concentration of Pi remained low whereas concentrations of ATP and ADP increased to levels in between those of controls and the 130-day-old infection. In addition, levels of phosphorylethanolamine (PE) and of an unknown metabolite significantly increased in this latter group. Worm extracts contained high levels of glycerophosphorylcholine (GPC), Pi, fructose 1,6-diphosphate (FDP), PE, diphosphodiesters (DPDE), phosphorylcholine (PC) and glycerolphosphorylethanolamine (GPE) in order of declining concentrations, respectively.

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

[31P]-Nuclear magnetic resonance (NMR) in vivo spectra of Echinococcus multilocularis cysts growing subcutaneously in Meriones unguiculatus showed prominent signals due to phosphomonoesters (PME), phosphodiesters (PDE), inorganic phosphate (Pi) and the alpha, beta and gamma phosphate groups of adenosine triphosphate (ATP). The internal pH of the parasite cysts was 6.7-6.8. The 31P 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 beta-hydroxybutyrate. Glycogen, creatine, glycine, taurine, betaine, cholines and lactate were present at similar concentrations in cyst material from both locations.

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.

Mesocestoides corti: a GC/MS study of the effects of oxaloacetate and iodoacetate on the isotope ratios in succinate and lactate excreted in the presence of NaH13CO3.

The current study was undertaken to gain further insight into the carbohydrate metabolism of the proliferating larvae of Mesocestoides corti by studying the effect of the metabolic inhibitors oxaloacetate and iodoacetate on the incorporation of label from NaH13CO3 into the excretory products lactate and succinate. These products were converted to their methyl derivatives and analyzed by gas chromatography/mass spectrometry (GC/MS) to determine the isotope ratios. The percentage of [1-13C]lactate, [1-13C]succinate, and [1,4-13C2]succinate decreased in the presence of oxaloacetate; iodoacetate did not significantly influence the relative amount of the former, but markedly increased percentages of the latter two. The data provide information on the relative rates of the pathways and steps within them and the influence of the inhibitors on these pathways.

H and 13C n.m.r. studies of serum from normal and Echinococcus multilocularis infected jirds.

The major components of the 13C and high field region of the 1H nuclear magnetic resonance (n.m.r.) spectra of normal and Echinococcus multilocularis infected jirds were identified and compared. Substantial depletion of the glucose and fatty acid chains from lower density lipoproteins was detected in sera from infected animals. In addition, this proliferating metacestode markedly changed the appearance of the spectral region recently assigned to N-acetyl protons of carbohydrate side chains of N-acetylated glycoproteins.

Hymenolepis diminuta: nuclear magnetic resonance analysis of the excretory products resulting from the metabolism of D-[13C6]glucose.

Excretory products of the tapeworm Hymenolepis diminuta, fed D-[13C6]glucose in vitro for 90 min, were studied using 1H and 13C nuclear magnetic resonance spectroscopy. Signals due to lactate, succinate, acetate, and alanine were identified in the spectra. Several differently labeled species were present for these metabolites; the variations of higher concentration were a consequence of metabolic factors while those of lower concentration could be accounted for by residual 12C in the glucose. The two major labeled lactates, U-13C and 2,3-13C2, were in the ratio 2:1, respectively, and the three major labeled succinates, 1,2,2'-13C3,2,2'-13C2, and U-13C, were present in the ratio 20:10:3, respectively. The different species of labeled end products are related to the overall glucose metabolism of H. diminuta.

Comparison of the effects of imidazo[1,2-a]pyridine-2-carbamates and benzimidazole-2-carbamates on the development of Hymenolepis nana in Tribolium confusum.

The anthelmintic properties of several imidazo[1,2-a]pyridine carbamates and benzimidazole carbamates against Hymenolepis 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.