Effects of 5-hydroxytryptamine and histamine on establishment, production, and reproduction by Hymenolepis diminuta in the final and intermediate hosts

1982 ◽  
Vol 60 (4) ◽  
pp. 725-728 ◽  
Author(s):  
C. H. Cho ◽  
D. F. Mettrick
Keyword(s):  
Dose Rate ◽  
Immunological Response ◽  
Chronic Administration ◽  
Hymenolepis Diminuta ◽  
Gravid Proglottid ◽  
Intermediate Hosts ◽  
Rat Intestine ◽  
Production Growth ◽  
Lower Dose Rate ◽  
Host Parasite

The effects of chronic administration of 5-hydroxytryptamine (serotonin, 5-HT) and histamine for 15 days, commencing 24 h after infection, on establishment, production, and reproduction by the tapeworm Hymenolepis diminuta in the rat intestine have been studied. Chronic treatment with 5-HT at the rate of 10 or 20 mg/rat per 24 h neither affected parasite production (growth) nor caused a significant rejection of the infection by the rat host. The number of eggs shed by the parasite and the number of eggs per gravid proglottid were reduced over the final 24-h period prior to sacrifice of the hosts.Similar treatment with histamine at the higher dose rate resulted in a significant reduction in the size of the infection and a significant increase in average worm weight. The number of eggs per gram of faeces and per proglottid was significantly reduced, as was also the number of cysticercoids that developed in beetles (Tribolium confusum) that had been fed on the gravid proglottids from histamine-treated worms. Results at the lower dose rate were similar, although the changes were smaller. The histamine treatment may have induced an immunological response by the host to the infection similar to that previously reported for this particular host–parasite system at higher levels of infection or in challenge infections.

Susceptibilities of Various Snail Intermediate Hosts of Schistosoma mansoni to Different Strains of the Parasite

1965 ◽  
Vol 39 (4) ◽  
pp. 363-376 ◽  
Author(s):  
M.F.A. Saoud
Keyword(s):  
Puerto Rico ◽  
Schistosoma Mansoni ◽  
Intermediate Hosts ◽  
Considerable Evidence ◽  
The Past ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Different Strains ◽  
Host Parasite ◽  
Comprehensive Studies

In the past two decades, considerable evidence has accumulated in the literature about the differences in the susceptibility of various intermediate hosts of Schistosoma mansoni to different strains of the parasite. Comprehensive studies on this aspect of host-parasite relationship have been published by Files & Cram (1949), Abdel-Malek (1950) and Files (1951). The results of more recent studies have been reported by Wright (1962) and Saoud (1964).In the present paper, the writer has studied the susceptibility of four intermediate hosts of S. mansoni from Brazil, Puerto Rico, Egypt and Tanganyika to some strains of the parasite.

Insights into the molecular basis of host behaviour manipulation by Toxoplasma gondii infection

2017 ◽  
Vol 1 (6) ◽  
pp. 563-572 ◽  
Author(s):  
Pierre-Mehdi Hammoudi ◽  
Dominique Soldati-Favre
Keyword(s):  
Toxoplasma Gondii ◽  
Stress Responses ◽  
Molecular Mechanisms ◽  
Brain Regions ◽  
Intermediate Hosts ◽  
Toxoplasma Gondii Infection ◽  
Host Parasite ◽  
Host Behaviour ◽  
The Brain ◽  
Brain Homeostasis

Typically illustrating the ‘manipulation hypothesis’, Toxoplasma gondii is widely known to trigger sustainable behavioural changes during chronic infection of intermediate hosts to enhance transmission to its feline definitive hosts, ensuring survival and dissemination. During the chronic stage of infection in rodents, a variety of neurological dysfunctions have been unravelled and correlated with the loss of cat fear, among other phenotypic impacts. However, the underlying neurological alteration(s) driving these behavioural modifications is only partially understood, which makes it difficult to draw more than a correlation between T. gondii infection and changes in brain homeostasis. Moreover, it is barely known which among the brain regions governing fear and stress responses are preferentially affected during T. gondii infection. Studies aiming at an in-depth dissection of underlying molecular mechanisms occurring at the host and parasite levels will be discussed in this review. Addressing this reminiscent topic in the light of recent technical progress and new discoveries regarding fear response, olfaction and neuromodulator mechanisms could contribute to a better understanding of this complex host–parasite interaction.

Characterization in vitro of H+ secretion and H+:Na+ exchange by an organism normally inhabiting a CO2-rich environment: Hymenolepis diminuta (Cestoda) in the rat intestine

1978 ◽  
Vol 56 (11) ◽  
pp. 2344-2354 ◽  
Author(s):  
R. B. Podesta
Keyword(s):  
Metabolic Pathways ◽  
Intestinal Parasite ◽  
Hymenolepis Diminuta ◽  
Ambient Fluid ◽  
Rat Intestine ◽  
Ion Concentrations ◽  
Intracellular Ion Concentrations ◽  
Metabolic Reactions ◽  
Stimulation Of

H+ and Na+ transport by the intestinal parasite Hymenolepis diminuta were studied in vitro. The flatworms acidified the ambient fluid by secreting H+ and the acidification could not be correlated with organic acid excretion. Ambient CO2-independent H+ secretion was attributed to protons of metabolic origin: dephosphorylation reactions and ionization of organic acids within the tissues. Ambient CO2-dependent H+ secretion was attributed to protons produced as a result of the hydration of CO2 within the tissue and to the stimulation of anaerobic metabolic pathways by CO2 acting as a cosubstrate in energy metabolism. Studies in which Na+ uptake was stimulated by CO2 or glucose and inhibited by ouabain, amiloride, or Na+ replacement suggested a partial direct coupling of Na+ absorption and H+ secretion but the different activation energies and the effect of buffer anions other than HCO3− suggested an indirect interaction. Various interactions were considered, including the effect of CO2 and intracellular ion concentrations on metabolic reactions leading to the supply of protons for H+ secretion and energy for ion transport.

The oestrogenicity of equol in sheep

1984 ◽  
Vol 103 (3) ◽  
pp. 395-399 ◽  
Author(s):  
R. Kaziro ◽  
J. P. Kennedy ◽  
E. R. Cole ◽  
P. T. Southwell-Keely
Keyword(s):  
Growth Rate ◽  
Plasma Concentration ◽  
Plasma Level ◽  
Dose Rate ◽  
Dehydrogenase Activity ◽  
Intramuscular Injection ◽  
Uterine Weight ◽  
Lower Dose Rate ◽  
Short Time ◽  
Glucose 6 Phosphate Dehydrogenase

ABSTRACT The effects of intramuscular injection of synthetic racemic equol (±3-(4-hydroxyphenyl)-3,4-dihydro2H-1-benzopyran-7-ol) into wethers have been examined with respect to maintenance of plasma level, teat growth rate and the activity of the respiratory enzyme glucose-6-phosphate dehydrogenase. At a dose rate of 1·03 mmol/day a steady rise in 'total' (free plus conjugated) equol in plasma occurred to 1·78μmol/l in 4 days. A dose rate of 2·07 mmol/day produced only a further slight increase in plasma equol. At a lower dose rate of 0·52 mmol/day the plasma concentration reached 0·62 μmol/l in 2 days and this was not exceeded thereafter. At the dose rate of 1·03 mmol/day over 7 days significant increases in teat length and glucose-6-phosphate dehydrogenase activity occurred but no significant changes were observed at the dose rate of 0·52 mmol/day. It appears that threshold levels of intake of equol which maintain a plasma level of about 1·65 μmol/l are needed for oestrogenic effects to become apparent within a relatively short time. Administration of 1·03 mmol/day over 5 days to ovariectomized ewes produced significant increases in uterine weight equivalent to those produced by 92 nmol stilboestrol dipropionate. Thus stilboestrol was apparently 56000 times more potent than racemic equol. J. Endocr. (1984) 103, 395–399

Population regulation in ticks: the role of acquired resistance in natural and unnatural hosts

Parasitology ◽  
1979 ◽  
Vol 79 (1) ◽  
pp. 141-156 ◽  
Author(s):  
Sarah E. Randolph
Keyword(s):  
Population Regulation ◽  
Acquired Resistance ◽  
Subsequent Development ◽  
Immunological Response ◽  
Threshold Level ◽  
Tick Population ◽  
Dependent Manner ◽  
Laboratory Mice ◽  
Natural Hosts ◽  
Host Parasite

SUMMARYAttachment, engorgement and subsequent development of successive infestations of Ixodes trianguliceps larvae and nymphs on natural hosts, Apodemus sylvaticus, and unnatural hosts, laboratory mice, are compared. In laboratory mice, primary infestations above a threshold level of about 10 ticks elicit an immunological response which reduces, in a density-dependent manner, the rate of successful tick engorgement during subsequent infestations. In contrast, in A. sylvaticus successive infestations of larvae result in unchanged or slightly improved survival through to nymphs. The relevance of these results to the concept of host-parasite co-evolution and to tick population regulation is discussed.

Changes in the distribution of Hymenolepis diminuta (Cestoda: Cyclophyllidea) within the rat intestine during prepatent development

1970 ◽  
Vol 48 (4) ◽  
pp. 761-769 ◽  
Author(s):  
Christine E. Cannon ◽  
D. F. Mettrick
Keyword(s):  
Small Intestine ◽  
Weight Distribution ◽  
Attachment Site ◽  
Pyloric Sphincter ◽  
Hymenolepis Diminuta ◽  
Rat Intestine ◽  
Intestinal Length ◽  
Attachment Sites ◽  
The Mean

The changes in the distribution of Hymenolepis diminuta within the rat intestine have been followed over the period 3 to 16 days postinfection using rats, each infected with 10 cysticercoids of H. diminuta, fed ad libitum on Purina Rat Chow.The parameters investigated were distribution of scolex attachment sites in the intestine, and distribution of parasite biomass in the intestine based on strobila length, ex vivo weight distribution, and in vivo weight distribution. Both the scoleces and biomass of 3- and 5-day-old worms are concentrated in the second quarter of the intestine. The mean scolex attachment point for 5-day-old worms was 39% of the total intestinal length behind the pyloric sphincter. Between days 5 and 7 there was a marked anterior migration of the young worms, so that at 7 days the mean scolex attachment site was 15% of the total intestinal length behind the stomach. Over the same period of time the mean in vivo weight distribution moved forward from a point 44% behind the pyloric sphincter to one only 23% along the intestine. After 7 days there was a gradual posteriad spreading of the scolex attachment sites and of the parasite biomass. Hymenolepis diminuta can attach itself anywhere in the anterior 75% of the intestine, including in front of the opening of the bile duct: no worms were found in the small intestine extending back into the caecum.The pattern of migration and the changes in worm distribution in the intestine suggest that H. diminuta selects an appropriate, but changing position, on one or more of the gradients that have been demonstrated or postulated along the length of the small intestine.It is also suggested that the long-term migration during prepatent development is interrelated, but distinct from the daily migrational movements that H. diminuta undergoes within the small intestine.

scholarly journals A method for measuring the attachment strength of the cestode Hymenolepis diminuta to the rat intestine

2016 ◽  
Vol 91 (6) ◽  
pp. 762-766
Author(s):  
W. Xie ◽  
G.R. Racz ◽  
B.S. Terry ◽  
S.L. Gardner
Keyword(s):  
Tensile Test ◽  
Medical Device ◽  
Functional Morphology ◽  
Medical Devices ◽  
Hymenolepis Diminuta ◽  
Test Machine ◽  
Rat Intestine ◽  
Attachment Strength ◽  
Internal Parasites

AbstractA unique adaptation of many internal parasites of mammals is their ability to stay in the intestine for extended periods of time and resist the normal peristaltic movements and forces that push and expel material. To better understand parasite adhesion behaviour and replicate their attachment method in medical devices, an experiment was designed and performed using the rat tapeworm, Hymenolepis diminuta. The experiment employed a tensile test machine and a digital scale and was designed to calculate the attachment strength of the scolex to the mucosa through the change of the value of the digital scale during the tensile test. The attachment force of H. diminuta is 0.021 ± 0.011 g. This method could be applied in studies of parasite biomechanics and the results may help medical device researchers to better mimic the unique functional morphology of this species of parasite.

Variation in the size and position of Hymenolepis diminuta (Cestoda: Cyclophyllidea) within the rat intestine

1969 ◽  
Vol 47 (6) ◽  
pp. 1091-1101 ◽  
Author(s):  
D. F. Mettrick ◽  
Lorna C. Dunkley
Keyword(s):  
Body Weight ◽  
Experimental Design ◽  
Frequency Distribution ◽  
Dry Weight ◽  
Pyloric Sphincter ◽  
Hymenolepis Diminuta ◽  
Female Rats ◽  
Rat Intestine ◽  
Male And Female ◽  
Male And Female Rats

Data on the dry weight of 410 worms from both male and female rats is shown not to differ significantly from the normal (Gaussian) frequency distribution. This finding justified the use of statistics based on this function.Host body weight is shown to have a highly significant (P < 0.01) effect upon worm dry weight. The heavier the rat, the smaller the worms. An experimental design taking rat body weight into consideration is shown to be up to 36% more efficient in demonstrating differences between groups than one that ignores this source of variation. The point of scolex attachment behind the pyloric sphincter also has a significant effect (P < 0.05) upon worm dry weight. The nearer the scolex is to the stomach, the smaller the worm.The distribution of worm biomass in the intestine does not follow a normal (Gaussian) frequency, but is both asymmetrical (P < 0.001) and flattened (P < 0.001). Over 50% of the parasite biomass lies within the second quarter of the intestine. The distribution of the median points of worm strobilae in the rat intestine is also asymmetrical (P < 0.01) with a peak in the zone which represents a distance of 30–35% from the stomach.The migration of H. diminuta within the rat intestine results in the greater part of the parasite body lying in the second quarter of the intestine. The median points of the strobilae are concentrated at the junction of the first and second quarters of the intestine. This region of the rat intestine appears to offer the optimum site for the growth of H. diminuta.

The dynamics of the host-parasite relationship

Parasitology ◽  
1965 ◽  
Vol 55 (3) ◽  
pp. 515-525 ◽  
Author(s):  
J. K. Dineen ◽  
A. D. Donald ◽  
B. M. Wagland ◽  
Jan Offner
Keyword(s):  
Egg Production ◽  
Technical Assistance ◽  
Parasitic Infection ◽  
Immunological Response ◽  
Major Effect ◽  
Infective Larvae ◽  
Parasite Relationship ◽  
Group 3 ◽  
Host Parasite ◽  
Group 1

Two groups of sheep born and raised worm-free were dosed with 3000 infective Haemonchus contortus larvae. Group 1 were each given a single dose of infective larvae on day 0 while the group 3 animals were dosed with 100 infective larvae per day for 30 consecutive days. The results of faecal worm-egg counts performed on alternative days, and of differential worm counts carried out on animals slaughtered at crucial times during the course of infection, showed that retardation of development at the 4th larval stage occurred in the group 3 infections and was the major effect of control of the parasitic burden. There was no evidence that egg production per female was affected.Three animals of the nineteen infected in group 1 died during the course of the experiment owing to the pathogenic effects of the worm burden. Deaths did not occur among the animals of group 3. This finding was correlated with the observation that haematocrit levels were consistently lower among the animals of group 1 than among those of group 3.The results are interpreted in terms of the theory of threshold behaviour of the immunological response to parasitic infection.We are greatly indebted to Dr D. F. Stewart for his interest and constructive criticism during the course of these studies, and to Mr E. Teleki and Misses Helen Giller and Lindy Stothart for their valuable technical assistance.

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