Study of the effects of insulin on the migration of Hymenolepis diminuta in rats

The effects of insulin on worm (Hymenolepis diminuta) migration was studied. Insulin injection (20 U/kg, s.c.) significantly increased gastric acid output but did not affect the serotonin content of blood, intestinal lumen or worms. The drug produced, dose-dependently, posteriad migration of the worms in rats without pylorus-ligation but ligation of the pylorus prevented this migration. It is concluded that the hypersecretion of gastric acid induced by insulin is responsible for the posteriad migration of H. diminuta in rats.     

Concurrent infections of the trematode Echinostoma caproni and the tapeworms Hymenolepis diminuta and Hymenolepis microstoma in mice

Superimposing the intestinal tapeworm Hymenolepis diminuta on an established infection with the trematode Echinostoma caproni or simultaneous infection of mice with H. diminuta and Hymenolepis microstoma caused destrobilation and expulsion of H. diminuta, whereas establishment and growth of H. microstoma under the same infection regimes were not affected. In contrast, simultaneous superimposition of H. diminuta and H. microstoma on an established E. caproni infection caused destrobilation and expulsion of both H. diminuta and H. microstoma.     

The occurrence and distribution of 5-hydroxytryptamine in Hymenolepis diminuta and H. nana

The presence of 5-HT in Hymenolepis diminuta and Hymenolepis nana was detected by 2 biochemical methods and as yellow fluorescence in a histochemical method. In H. diminuta, 5-HT was found in a concentration of about 1.2 micron/g; this amount did not vary significantly in worms aged 6 to 18 days or more or in various regions of the worm. In H. nana, 5-HT was found in a concentration of about 1.8 micron/g. It was histochemically localized in H. diminuta and H. nana in a pattern similar to that of acetylcholinesterase previously described in these 2 cestodes, and it may be the opposing neuro-transmitter to acetylcholine. The lack of 5-HT in the vestigial rostellum of H. diminuta may be correlated with loss of function of this organ.     

Intestinal contractions and migration behaviour in Hymenolepis diminuta.

The aim of this study was to determine if intestinal contractions were important in the migration behaviour of the rat tapeworm Hymenolepis diminuta. The objectives were to investigate the intestinal motility responses of the host to a meal which initiates worm migration, and the worms' responses to an artificial peristaltic contraction. A 1 g glucose meal elicited a significant orad migration by H. diminuta in the small intestine of the rat host when compared to water-fed controls (P less than 0.05). The glucose meal also significantly increased the transit rate, and thus, frequency of intestinal contractions in the small intestine of the rat, when compared to water-fed controls (P less than 0.05). Application of a circumintestinal ligature (6.3 g) (simulating an intestinal peristaltic contraction) resulted in significant worm migration when the ligature was applied in regions containing the worm's strobila as compared to controls where loose ligatures were tied in regions containing the strobila, or to controls where tight ligatures were tied ahead of the worm's strobila. These results suggest that H. diminuta migrates in an orad direction in response to the mechanical pressure produced by intestinal contractions induced by host feeding. It is concluded that contractions of the small intestine are an important cue in the migration behaviour of this cestode.     

Delayed expulsion of Hymenolepis diminuta in Trypanosoma brucei infected mice

An experiment was conducted to study the effect of Trypanosoma brucei on the expulsion of Hymenolepis diminuta in the mouse. The study showed that T. brucei given 8 days before infection with H. diminuta resulted in a significant delay in the expulsion of the H. diminuta worm burden. This finding is suggested to be due to the immunosuppressive effect of the trypanosome.     

Hymenolepis diminuta: lack of sulphate activation and sulphotransferase activity

There is no evidence that Hymenolepis diminuta can carry out sulphoconjugation reactions. Neither whole worms nor worm extracts were able to sulphate 4-methylumbelliferone. No sulphotransferase activity could be demonstrated in H. diminuta using a variety of substrates, nor was H. diminuta capable of synthesising the sulphate donor 3'-phosphoadenosine-5'-phosphosulphate from ATP and inorganic sulphate. Possible alternative sources of active sulphate in this parasite are discussed.     

Identification of ADPR-transferase activity in the rat tapeworm, Hymenolepis diminuta

1. The nuclear fraction of the rat tapeworm Hymenolepis diminuta (Cestoda) contains the enzyme adenosine diphosphoribosyl transferase (ADPR-transferase). 2. The enzyme catalyzes the postsynthetic modification of some nuclear proteins by the covalent attachment of the (ADP-ribose) moiety of NAD to such proteins. 3. The reaction is dependent on DNA which contains strand-breaks, and chain lengths equivalent to (ADP-ribose) is estimated. 4. The formation of polynucleotide products was competitively inhibited by 3-acetamidobezamide, with a Km of 125 microM. 5. The catalytic properties of ADPR-transferase in Hymenolepis diminuta are similar to those in T. brucei.     

The Hymenolepis diminuta-golden hamster (Mesocricetus auratus) model for the evaluation of gastrointestinal anticestode activity

A novel laboratory anticestode assay was developed using Hymenolepis diminuta in the hamster. The commercial anticestode compounds, praziquantel, bunamidine, and niclosamide were active against patent infections of Hymenolepis diminuta in golden hamsters (Mesocricetus auratus) when given orally at 3.125, 100, and 200 mg/kg, respectively. The gastrointestinal nematode anthelmintics, cambendazole and mebendazole, were active at 50 mg/kg. Rafoxanide (fasciolicide) was active at 25 mg/kg, the lowest level tested. The coccidiostat, nicarbazin, was active at experimental levels (800 mg/kg and up). The anthelmintic-ectoparasiticide (endectocide), ivermectin, was inactive against the tapeworm at 0.5 mg/kg, as expected.     

Phloretin inhibition of glucose transport by the tapeworm Hymenolepis diminuta: a kinetic analysis

Phloretin non-competitively inhibits glucose and methionine absorption by Hymenolepis diminuta (Ki = 0.24 and 1.48 mM, respectively). Inhibition of glucose transport by phloretin is reversible. Phloretin and phlorizin binding sites on the surface of H. diminuta are distinct. Phloretin does not inhibit Na+ transport independent of glucose transport in H. diminuta. The data suggest that phloretin inhibits absorptive functions across the surface of H. diminuta via non-specific binding sites associated with the lipid portion of the worm outer membrane.     

Differential establishment and survival of Hymenolepis diminuta in syngeneic and outbred rat strains.

Experimental Hymenolepis diminuta infection was carried out in inbred strains of rats (F344/N, JAR-2, LOU/M, TM, DA and DA-bg/bg) and outbred Wistar rats. All strains became infected with this cestode, but clear strain-dependent variation in the susceptibility to H. diminuta infection was observed. Marked differences in worm persistence and worm weight were found at 6 weeks post-infection in TM and DA rats. These strains would be useful to clarify the interactions between H. diminuta and its rat host.     

Reduction and oxidation of cytochrome C by Hymenolepis diminuta (Cestoda) mitochondria

Mitochondrial membranes of adult Hymenolepis diminuta catalyzed inhibitor-sensitive ferricytochrome c reduction. Cytochrome c reductase activity was noted when NAD(P)H or succinate served as the reductant with the NADH-coupled reaction being most prominent. Both rotenone-sensitive and -insensitive reduced pyridine nucleotide-coupled activities were apparent. Ferrocytochrome c oxidase activity also was catalyzed by H. diminuta mitochondrial membranes and this reaction was sensitive to azide and cyanide. A cytochrome c peroxidase activity was associated primarily with the mitochondrial soluble fraction of adult H. diminuta. The possibility that the activities observed may contribute to the elimination of peroxide in the helminth system is considered.     

The effect of the expulsion phase of Trichinella spiralis on Hymenolepis diminuta infection in rats.

The effect of the intestinal changes brought about by the expulsion of Trichinella spiralis in rats was studied in relation to the growth and survival of a concurrent infection with Hymenolepis diminuta, a cestode not normally rejected by the rat in low-level infections. Growth of H. diminuta was stunted in rats given T. spiralis just before, or after, infection with H. diminuta, the stunting being more pronounced when the cestode was given closer to the period of inflammation. There was no loss of the cestode from dual-infected rats and no evidence for destrobilation was found. Lower T. spiralis burdens had a correspondingly weaker effect on growth of H. diminuta, and stunting was abolished by administration of the anti-inflammatory drug cortisone acetate. It is concluded that the stunting of H. diminuta is probably due to the non-specific inflammatory component of the rat's response to T. spiralis infection.     

Amino acid metabolism in the rat tapeworm, Hymenolepis diminuta

1. The amino acid metabolism of the rat tapeworm, Hymenolepis diminuta was investigated. 2. In addition to the characteristic end products of helminth metabolism, H. diminuta also forms substantial amounts of 14C-alanine during incubations in 14C-glucose. 3. Of 10 amino acids tested, only 14C-labelled asparate and, to a lesser extent alanine, generated substantial amounts of 14CO2 when incubated with H. diminuta. 4. 14C-aspartate was incorporated into both succinate and acetate, major products of the worms mitochondrial metabolism, but the rates were low when compared to the metabolism of exogenous glycogen. 5. These results suggest that amino acid metabolism in H. diminuta is very limited.     

Mucosal mast cell response to Hymenolepis diminuta infection in different rat strains.

Five-week-old DA male rats infected with 10 Hymenolepis diminuta cysticercoids showed significant mastocytosis 6 weeks post-infection and low persistence of worms. In F344/N rats, however, no mastocytosis and no worm loss occurred during a 6 week infection. Mucosal mast cells appear to be associated with the expulsion of H. diminuta from DA rats.     

Ca2+ inhibition of brush border alkaline phosphatase activity in Hymenolepis diminuta

The brush border membrane of Hymenolepis diminuta contains several Ca2+-dependent enzymes. Following our isolation of a Ca2+-dependent modulator protein we examined the kinetic properties of the brush border marker alkaline phosphatase from fractionated and crude tegument. We show that this enzyme is inhibited by Ca2+ concentrations approaching those in the calcareous corpuscles of H. diminuta.     

Trypsin adsorption by Hymenolepis diminuta (Cestoda)

Significant amounts of radioactivity were associated with Hymenolepis diminuta following incubation in 3H-trypsin. Autoradiography of worms incubated in 3H-trypsin for 30 min demonstrated that all radioactivity was associated with the worm's surface (tegument). The amount of 3H-trypsin adsorbed by the worms was not sufficient to account for the inactivation of this enzyme in the presence of intact worms. Unlabeled trypsin and poly-L-glutamate (but not poly-L-lysine) inhibited adsorption of 3H-trypsin, but were without effect on trypsin inactivation by H. diminuta. Therefore, trypsin was adsorbed by intact H. diminuta, but the process of adsorption apparently did not play any role in inactivation of the enzyme.     

Molecular cloning and characterization of Hymenolepis diminuta alpha-tubulin gene.

To isolate a full-length alpha-tubulin cDNA from an eucestode, Hymenolepis diminuta, a lambda phage cDNA library was constructed. The alpha-tubulin gene was cloned, sequenced and characterized. The H. diminuta alpha-tubulin consisted of 450 amino acids. This protein contained putative sites for all posttranslational modifications as detyrosination/tyrosination at the carboxyl-terminal of protien, phosphorylation at residues R79 and K336, glycylation/glutamylation at residue G445 and acetylation at residue K40. Comparisons of H. diminuta alpha-tubulin with all full-length alpha-tubulin proteins revealed that H. diminuta alpha-tubulin possesses 10 distinctive residues, which are not found in any other alpha-tubulins. Phylogenetic analysis showed that H. diminuta alpha-tubulin has grouped in a separated branch adjacent eucestode and trematodes branch with 92% bootstrap value (1000 replicates). In conclusion, this is the first report of H. diminuta cDNA library construction, cloning and characterization of H. diminuta alpha-tubulin gene.     

Beetle-to-beetle transmission and dispersal of Hymenolepis diminuta (Cestoda) eggs via the feces of Tenebrio molitor

When grain beetles (Tenebrio molitor) were fed eggs of Hymenolepis diminuta, many of the eggs passed intact through the beetles' intestines, and eggs were present in the beetles' feces for at least 48 hr after feeding. When uninfected T. molitor were fed beetle feces containing H. diminuta eggs, they became infected. Tenebrio molitor were fed on H. diminuta eggs and then placed in fresh bran for 48 hr. When uninfected T. molitor were placed in this bran, they became infected. Thus, feces from beetles that have ingested H. diminuta eggs serve as a source of eggs for other beetles, as well as a mechanism of egg dispersal.     

Monoamine oxidase in adult Hymenolepis diminuta (Cestoda).

A membrane-bound monoamine oxidase (EC 1.4.3.4) was demonstrated in homogenates of Hymenolepis diminuta. The enzyme oxidized a variety of biologically active amines (in decreasing order: dopamine, adrenaline, noradrenaline, tryptamine, tyramine, octopamine), there was, however, no activity with 5-hydroxytryptamine or benzylamine. No diamine oxidase (EC 1.4.3.6.) could be detected in H. diminuta (using histamine, cadaverine or putrescine as substrates). The monoamine oxidase from H. diminuta was not inhibited by azide, hydroxylamine or semicarbazide, but was inhibited by cupferron, alpha-alpha dipyridyl and iodoacetamide, and by the specific monoamine oxidase inhibitors pargyline, nialamide and iproniazid. Several anthelmintics were also found to be inhibitors of monoamine oxidase. The possible roles of monoamine oxidase in H. diminuta are discussed.     

Type I phosphodiesterase in the isolated, brush-border membrane of Hymenolepis diminuta

The isolated, brush-border membrane of Hymenolepis diminuta contained an enzyme which hydrolyzed phosphodiester bonds. This enzyme appeared to be a Type I phosphodiesterase (E. C. 3.1.4.1) (produces nucleoside 5'-phosphates) and had no activity against synthetic, Type II phosphodiesterase substrates (mononucleotides substituted at the 3' position). The effects of various potential inhibitors of enzymatic activity, and cation requirements of this enzyme, demonstrated a distinct difference between the phosphodiesterase and alkaline phosphatase activities of the isolated, brush-border membrane. SDS-polyacrylamide gel electrophoresis of the isolated membrane preparation, followed by localization of phosphodiesterase activity in the gels, indicated the enzyme had a molecular weight of approximately 87,000. Thus, the phosphodiesterase activity represents a previously undescribed, membrane-bound enzyme of the brush-border of Hymenolepis diminuta.