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PubMed1994

Intestinal myoelectric alterations in rats chronically infected with the tapeworm Hymenolepis diminuta.

This study determined that intestinal myoelectric activity was profoundly altered during a strictly luminal, chronic, tapeworm infection. Chronically implanted bipolar electrodes were attached to five sites on the serosal surface of the rat small intestine. One was placed on the duodenum, three on the jejunum, and the fifth on the ileum. Electromyographic recording in nonfasted unanesthetized animals was begun at day 5 postsurgery. All electromyographic recordings were analyzed for slow wave (SW) frequency, phase III frequency, duration of phase III, and percentage of SW with spike potentials. Three initial control recordings prior to infection confirmed the presence of normal interdigestive motility characterized by the three phases (I, II, III) of the migrating myoelectric complex (MMC). Two nonpropulsive myoelectric alterations were observed in infected animals: the repetitive bursts of action potentials (RBAP) and periods of sustained spike potentials (SSP). Myoelectric activity from infected animals indicated decreased cycling of the interdigestive MMC. RBAP and SSP were more prevalent in the distal small intestine corresponding to tapeworm location. The percent of spike potential activity indicated that there was a reversal in the spike potential gradient on the small intestine. The number of spike potentials was maximal in caudal and minimal in oral intestine. We propose that overall localized increases in myoelectric spike potential activity represent increased contractility and decreased propulsion triggered by the presence of the tapeworm. These motility changes were surprising, since the tapeworm Hymenolepis diminuta does not penetrate the intestinal mucosa. This interaction between parasite and host may prevent expulsion of the tapeworm from the small intestine.

Action Potentials↗
PubMed2003

Effects of tapeworm infection on male reproductive success and mating vigor in the red flour beetle, Tribolium castaneum.

Parasites may exert negative effects on host survivorship and reproductive success. The effects of parasites on female host fitness have been well documented; however, the effects of parasites on the reproductive success of male hosts and particularly the underlying mechanisms that alter male fitness are not well understood. Previous studies demonstrated that infection by rat tapeworm (Hymenolepis diminuta) reduced the fitness of male red flour beetles (Tribolium castaneum) in an environment of female mate choice and strong male-male competition. The present study determined the role of female mate choice and male insemination capacity on observed fitness reduction of male beetles by the tapeworm parasites. We found that infected males showed reduced mating vigor and consequently inseminated fewer females than did uninfected males. Specifically, tapeworm infection reduced the number of offspring sired by a male by 14-22% even when male-male competition and female mate choice were absent. Further, the insemination capacity of males diminished by 30% because of infection. Female beetles did not discriminate against infected males in precopulatory mate choice experiments. Copulatory courtship, a determinant of postcopulatory female choice, was not significantly different between infected and uninfected males. Hence, we concluded that female beetles did not show either pre- or postcopulatory choice against tapeworm-infected males. Therefore, tapeworm-induced reduction in the reproductive success of male beetles possibly results from altered reproductive biology, such as lower mating vigor and decreased sperm quantity or quality.

Animals↗
PubMed2003

Guanosine 3',5'-cyclic monophosphate: a tapeworm-secreted signal molecule communicating with the rat host's small intestine.

Tapeworms alter the physiological environment of the host's small intestinal lumen by contracting the intestinal smooth muscle, thereby slowing the transit of intestinal contents. We hypothesize that parasite-to-host molecular signaling is responsible for the specific patterns of small intestinal smooth muscle contraction observed both during tapeworm infection and after the infusion of tapeworm-secreted molecules into the intestinal lumen of unanesthetized rats. Of the tapeworm-secreted compounds tested, only lumenal infusion of guanosine 3',5'-cyclic monophosphate (cGMP) induced contractile patterns that mimic those observed during tapeworm infection. The response to cGMP occurred in a concentration-dependent fashion. Our study clearly demonstrates that cGMP can serve as an extracellular signal molecule regulating small intestinal motility mechanisms in vivo.

Action Potentials↗
PubMed2004

Portrait of human tapeworms.

The tapeworms of the genus Taenia that infect human beings are T. solium, T. saginata and T. saginata asiatica. Taenia solium and T. saginata exhibit unequivocal features that characterize them; in contrast, only recent DNA studies, morphological characteristics, and epidemiological and sanitary aspects indicate that T. saginata asiatica is a subspecies of T. saginata. These 3 tapeworms occur in humans in their adult stage, and the intermediate hosts are pigs for T. solium and T. saginata asiatica and cows for T. saginata. Their identification is crucial considering the migratory increase from Asia to the Western Hemisphere and the fact that these tapeworms coexist in the same environment in Asia; furthermore, it is estimated that movement in both directions across the United States-Mexico border exceeds 200 million persons per yr, and thus, opportunities for acquiring and transporting T. solium infections are multiplied. It is not easy to distinguish among these tapeworms; therefore, a comparative diagram of the 3 parasites is shown in this article, which will facilitate their identification. All morphological features, some of which allow for identification, are clear and can be easily distinguished among the 3 tapeworms.

Animals↗
PubMed2001

[The structure of low-abundance and crowded infrapopulations of the tapeworm Hymenolepis diminuta inbred line--WMS IL1].

An average of 4.9 tapeworms were discovered on day 7 of a low-abundance H. diminuta infection of rats of race WAG alb. After 11 months, the mean was only relatively slightly lower at 3.6. These means represent 97.1 and 71.4% of the 5 cysticercoids supplied. In turn, 7 days and 11 months after rats were supplied with 110 cysticercoids, the respective percent-ages were 85.1 and 56.0. All 7- and 12-day tapeworms from the low-abundance and crowded infrapopulations were characterized by the presence of a terminal proglottid of lingulate shape, in which the excretory canals joined. In contrast, older (48-day and 11-month-old) worms showed typical apolysis of gravid proglottids. There were no reports of the destrobilation of tapeworms, and the relatively large number of tapeworms persisting 11 months into the infection is particularly noteworthy. The results point to the lack of any rapid rejection of tapeworms of the kind characterized in many other studies on H. diminuta.

Animals↗
PubMed1985

[Tapeworms in the Netherlands].

Scientists have been discussing the nature of helminths, and particularly tapeworms, for ages. A synopsis of the ancient literature and literature of the Middle-Ages concerned with this subject is presented. Even today a number of remarkable stories about tapeworms is being told. One of them is that tapeworms do not occur in The Netherlands. The incidence of the tapeworm Taenia saginata in man in The Netherlands was carefully calculated from figures on cysterci observed in bovine carcases and estimates based on sales records of anthelmintics. It was concluded that tapeworms are relatively common (0,2-0,3%). The life cycle of Taenia saginata showed a remarkably constant pattern during the past twenty-five years.

Animals↗
PubMed1995

[Comparison of the variability of tapeworms obtained as a result of infecting rats with Hymenolepis diminuta larvae of different ages].

In Hymenolepis diminuta WMS "strain" tapeworms which were obtained 2.5 months after the administration to rats of 2-month old larvae--cysticercoids++, isolated from Tribolium destructor, only one-sided position of genital pores (PGP) developed. The extended 7-month duration of the invasion of H. diminuta larvae stimulates the development of variable PGP already in 14.1% of 2.5-month tapeworms. In tapeworms with exclusively one-sided PGP in the first of the two groups mentioned, the number of type 1p2a proglottids (1 testis on the poral side and 2 testes on the aporal side) as well as type 0p3a, 1p3a and 2p1a amounted to 88.2%, 5.5%, 4.2% and 0.5%, respectively and similarly in the second group--88.3%, 5.6%, 4.5% and 0.6%, respectively. In tapeworms with variable PGP the mean number of the types of proglottids mentioned was different from (86.0%, 4.1%, 3.8% and 4.1%, respectively) the same figure in tapeworms with one-sided PGP. Particularly high correlation was found to occur between the number of PGP variations and type 2p1a proglottids (r = +0.928, P < 0.01).

Age Factors↗
PubMed1995

Intensified morphological variability during patency in Hymenolepis diminuta originating from inbred tapeworm--WMS IL1.

Variable position of genital ducts and pores (PGP) was found in 23.3% of five months old tapeworms obtained as a result of administering to rats a dose of 6 cysticercoids proceeding from the third generation of inbred Hymenolepis diminuta--WMS il1. In tapeworms coming from generations no 18 and 32 PGP changes were reported only in 7.5 month, with only 5.9% of strobilas in the 32 generation group being characterized by this feature. These results indicate a time shift with respect to the appearance of PGP changes in tapeworms proceeding from latter inbred generations to a further period of tapeworm invasion in rats. The number of PGP changes is positively correlated with the number of type 2p1a proglottids (two testes on the poral and one on the aporal side). The average number of type Op3a proglottids increases with the number of generations. In 5-month old tapeworms of unilateral PGP coming from generation no 3, 18 and 32 it amounts to 5.9%, 6.6% and 8.1%, respectively.

Animals↗
PubMed1995

[Stimulation of morphological changes in tapeworms from inbred Hymenolepis diminuta--WMS IL1].

The investigations focused on tapeworms obtained as a result of the administration to individual rats a dose of 6 cysticercoids coming from the 39th and 40th generation of one-specimen inbred Hymenolepis diminuta-WMS il1. In 7.5-month old tapeworms the position of genital pores (PGP) was exclusively right-hand side with the genital ducts typical of this feature. Type Op3a proglottids were the most common deviation from the typical number and topography of testes-1p2a (one testis between the ovary and the genital pore marking the poral side and two testes on the aporal side)-in such tapeworms. Their mean incidence amounted to 8.9%, exceeding by at least 2.9% the mean quantitative value of this feature in tapeworms proceeding from non-inbred H. diminuta "strains" which have been subjected to similar studies. 19.5-month old tapeworms, exactly a year older than the previous ones, all had variable PGP. The number of PGP changes was here correlated positively with the number of type 2p1a proglottids and negatively with the number of type 1p2a and 0p3a proglottids.

Animals↗
PubMed1997

Interactions between intestinal tapeworms and their hosts: present knowledge and problems.

This review on interactions between intestinal tapeworms and their hosts covers our knowledge and problems regarding the life-span of adult tapeworms, chronic versus acute infections and their background, destrobilation and its causes, genetic influence on immunity to tapeworms, spontaneous cure and effects of host immunocompetence, antibodies and cell-mediated immune responses on intestinal tapeworms. Furthermore, evidence of protective antigens, acquired immunity, concomitant immunity and strategies adopted by tapeworms to circumvent host defenses are discussed.

Animals↗
PubMed1999

Hymenolepis diminuta: glucose and glycogen gradients in the adult tapeworm.

Adult (20-day-old) Hymenolepis diminuta were cut into 12 pieces of equal length, and the individual pieces of the tapeworm's strobila were analyzed. There was a continuous gradient of decreasing concentrations of glucose (mM) and decreasing levels of glycogen (microgram/mg wt) in the strobila. The ethanol extracts of the individual pieces of strobila contained four compounds tentatively identified as disaccharides; the distributions of these compounds were different from those of glucose and glycogen. The distributions of glucose, glycogen, and the "disaccharides" changed when tapeworms were incubated for 1 h in saline or glucose. When compared, on a per-weight basis, to the most posterior sections of the strobila, the anterior sections absorbed more glucose and incorporated more glucose into glycogen. There was a continuous gradient of decreasing values along the tapeworm's strobila of the Vmax for glucose uptake, while the Kt values for glucose uptake changed only slightly. The data indicate that glucose and glycogen metabolism are most active in the anterior part of the tapeworm's strobila where new proglottids are produced and the initial stages of organogenesis occur.

Analysis of Variance↗
PubMed1990

Effects of larval tapeworm (Taenia taeniaeformis) infection on reproductive functions in male and female host rats.

This report examined the effects of larval tapeworm infection on the reproductive functions in both male and female host rats. Female rats were matched by age, then randomly assigned to control and treatment groups (infected with larval tapeworms). Estrous cycles were determined by vaginal smear with 95% of the control group exhibiting 4-day normal cyclicity and only 55% of the treated group exhibiting normal cycles. Female fertility was then evaluated for the normally cycling rats based on the percentage of successful matings on the evening of proestrus, number of implantation sites on Day 8 of pregnancy, and number of pups born at term. The normally cycling rats exhibited 96% successful mating, 12.95 +/- 1.80 implantation sites, and 11.20 +/- 1.80 pups born. Five months after larval tapeworm infection, the fertility parameters were decreased to 79%, 9.10 +/- 1.20, and 7.50 +/- 1.50, respectively. The control females were then used in a study of male fertility after larval tapeworm infection employing the same parameters used to test female fertility. At the onset of the study, control groups exhibited 95% successful mating, 12.50 +/- 1.50 implantation sites, and 11.60 +/- 1.60 pups born at full term. After the 5-month infection period, the parameters were substantially reduced to 29%, 6.20 +/- 0.80 implantation sites, and 5.10 +/- 0.80 pups, respectively. Average testosterone concentrations in serum and testis from control male rats were 8.80 +/- 0.95 ng/ml and 3.88 +/- 0.25 ng/mg protein, respectively. After the 5-month infection period, these levels were reduced to 2.47 +/- 0.31 ng/ml and 1.28 +/- 0.12 ng/mg protein, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Alterations in brush border membrane proteins and membrane-bound enzymes of the tapeworm, Hymenolepis diminuta, during development in the definitive host.

During growth and maturation of the tapeworm, Hymenolepis diminuta, significant decreases occur in the brush border membrane-bound alkaline phosphatase, phosphodiesterase, 5'-nucleotidase, adenosine triphosphatase and ribonuclease activities. These decreases are accompanied by qualitative and quantitative changes in the polypeptide profiles of the brush border membrane fraction. Gradients of enzymatic activities and polypeptide profiles are also demonstrable when mature tapeworms are cut into pieces and the brush border membrane of each piece analyzed individually. In fully developed tapeworms the enzymatic activities and polypeptide profiles of membrane preparations reflect mainly the contributions of the more mature proglottids; these proglottids constitute most of the tapeworm biomass. The most anterior sections of these fully developed worms are biochemically similar to young, developing worms.

Aging↗
PubMed1994

The distribution of calmodulin/calmodulin binding proteins in the rat tapeworm, Hymenolepis diminuta.

Live tapeworms have been fixed to retain antigenicity of their proteins, and subsequently prepared for electron microscopy. Thin sections of tapeworms were prepared from resin blocks. Sections were immunocytochemically labelled using a colloidal gold probe and viewed using transmission electron microscopy. Calmodulin was detected associated with cellular structures to which calmodulin has previously been linked in other higher eukaryotes. Calmodulin would appear to have a similar role of importance in tapeworms, as it does in higher eukaryotes although tapeworms are prevalently a syncitium.

Animals↗
PubMed2006

Lack of postmortem digestion of tapeworms in Golden hamsters experimentally infected with Taenia solium.

Taenia solium causes human neurocysticercosis, a public health problem in Mexico and other developing countries. Surprisingly, tapeworm carriers are very rarely found and in necropsy studies practically no tapeworms have been reported. In this paper we analyze the possibility that, after the death of the host, tapeworms could easily be destroyed in the intestine. Our experiments, performed in the hamster model, suggest that the absence of tapeworms in human intestine during necropsy is not due to postmortem digestion.

Animals↗
PubMed1998

Predictability of morphological gradients in the tapeworm, Hymenolepis diminuta.

The strobila of an adult tapeworm represents a continual gradient of developmental stages from immature to gravid proglottids. The purpose of this study was to determine if organogenesis (as measured by the developmental gradient) in tapeworms within a single host and among different hosts occurred at the same rates. Rats were infected with Hymenolepis diminuta and the tapeworms were recovered 20 days post-infection. The total number of proglottids in each worm was determined, and five 'benchmarks' of organogenesis were quantified. The data demonstrated that organogenesis in worms from a single host occurred at a relatively constant rate, but that rates in tapeworms from different hosts were different.

Animals↗
PubMed1999

Systematics of the Eucestoda: advances toward a new phylogenetic paradigm, and observations on the early diversification of tapeworms and vertebrates.

Evolutionary relationships of the Eucestoda have received intense but sporadic attention over the past century. Since 1996, the landscape has dramatically changed with respect to our knowledge of the phylogenetic relationships among the tapeworms. The 2nd International Workshop for Tapeworm Systematics (IWTS) held in Lincoln, Nebraska in October of that year provided the catalyst for development of novel hypotheses for inter- and intraordinal phylogeny. The working-group structure of the 2nd IWTS and results of phylogenetic studies are briefly introduced in the present manuscript. Higher-level phylogenies derived from parsimony analysis of independent data bases representing comparative morphology or molecular sequences were largely congruent and supported monophyly for the Eucestoda. The Caryophyllidea are basal; difossate forms such as the Pseudophyllidea are primitive; tetrafossates including the Tetraphyllidea, Proteocephalidea, Nippotaeniidea, Tetrabothriidea and Cyclophyllidea are derived; and hypotheses differed in the placement of the Trypanorhyncha and the Diphyllidea. These studies may provide a foundation for resolution of inter- and intra-ordinal relationships for the tapeworms. Additionally, the first comprehensive phylogenetic hypotheses for the Pseudophyllidea, Diphyllidea, Trypanorhyncha, the paraphyletic Tetraphyllidea + Lecanicephalidea, Proteocephalidea and Cyclophyllidea were developed during and subsequent to the 2nd IWTS. The stage is now set for continued and rapid advances in our understanding of the eucestodes. These studies have also served to re-emphasise the rich genealogical diversity of tapeworms and the temporally deep history for their origin. A co-evolutionary history and radiation of eucestodes may involve deep co-speciation with vertebrate host taxa, accompanied by some level of colonisation and extinction, extending into the Palaeozoic, minimally 350-420 million years ago.

Animals↗
PubMed2002

Small intestinal transections decrease the occurrence of tapeworm-induced myoelectric patterns in the rat.

Abstract Luminal infection by the noninvasive tapeworm, H. diminuta, alters rat small intestinal myoelectric activity. The significance of continuity between small intestinal enteric nervous system (ENS) and that of both the stomach/pylorus and colon/caecum regarding the induction of tapeworm-altered myoelectric patterns was evaluated. A total of 32 rats were implanted with four serosal electrodes placed at sites in the duodenum through the mid-jejunum. Sixteen of the 32 rats underwent intestinal transections and anastomoses at both the duodenum and ileum. After recording myoelectrical activity of both normal and transected intestines, eight rats from each group (normal and transected) were infected with H.diminuta. Phase III frequency, duration of the migrating myoelectric complex (MMC), slow wave frequency, percentage of slow waves associated with spike potentials and the occurrence of the the two tapeworm-initiated myoelectric patterns, repetitive bursts of action potentials (RBAP) and sustained spike potentials (SSP), were measured. In infected rats, the frequency of the RBAP and SSP electric patterns were significantly reduced by the double transection. Intestinal transection did not affect the other changes caused by infection, such as decreased MMC phase III frequency and percentage of slow waves associated with spike potentials. In conclusion, a small intestinal ENS in continuity with other segments of the GI tract is required to generate maximal numbers of tapeworm-induced SSP and RBAP myoelectric activity in the small intestine of the rat.

Anastomosis, Surgical↗