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Three experimental animal parasite models for assessing anthelmintic efficacy and immunopotentiating properties of natural products: protocols and applications
Full text linkIntroduction: Helminthic infections, including soil-transmitted helminths (STHs) and intestinal tapeworms, pose a major global health challenge, classified as neglected tropical diseases (NTDs). Objective: Current control efforts are hampered by expensive treatments, emerging drug resistance, and high reinfection rates. This necessitates the urgent discovery of new anthelmintic drugs and immunomodulatory compounds. Natural products are a promising source for these new therapies. Materials and methods: This paper introduces three experimental animal parasite models specifically designed to evaluate the effectiveness and immune-boosting properties of natural products, namely Hymenolepis diminuta (tapeworm) in mice, Ascaridia galli (nematode) in chickens, and Raillietina cesticillus (tapeworm) in chickens. Rationale: These models provide controlled environments for assessing potential therapeutic compounds and offer systematic methodologies for identifying effective and immunomodulatory natural products. Conclusions: A significant challenge in treating helminth infections is targeting larval stages embedded in host tissues, such as those seen with Hymenolepis nana in humans and hypobiotic trichostrongylid nematode larvae in ruminants. Therefore, demonstrating a natural product\u27s effectiveness against A. galli larvae embedded in the intestinal mucosa is particularly important. Such efficacy would indicate that the product possesses valuable physicochemical and pharmacological properties, paving the way for developing novel treatments against hidden, tissue-dwelling parasites in both humans and animals
Immunity to tapeworms: vaccination against Hymenolepis diminuta and role of the bursa of Fabricius in rejection of Raillietina cesticillus
Full text linkAttempts were made to vaccinate mice against infection with
Hymenolepis diminuta, a tapeworm rejected from the se hosts by an
immunologically- mediated mechanism. Various putative antigenic
preparations from the strobilated worm were tested. Marginal
protection, as compared with that induced by an oral infection from
cysticercoids, was obtained when mice were orally vaccinated with
multiple doses of whole worm antigens. Marginal protection was
also obtained when tegument antigens were given by this route.
Results from two other experiments with tegument antigens, however,
did not confirm this finding. No protection was obtained following
vaccination with antigens ,from sonic disruption of somatic cells,
exoantigens, saline extracts or egg antigens.
On the basis of evidence from other experimental models, it is
proposed that this failure to evoke strong protective immunity by
vaccination with killed worm antigens was possibly due to one or
more of the following factor s:
(i) the tapeworm protective antigens were not pre sent initially in
most of the preparations injected or that they were pre sent in
too Iowa quantity to stimulate immunity
(ii) the worm protective antigens were highly labile and they were
destroyed during preparation, probably by enzymes released
by the disintegrating worms themselves, or inactivated by
chemical reactions in the stomach or intestine when the se
preparations were given orally or intraduodenally.
(iii) . -the physicochemical characteristic s of the se protective antigens
had been altered during preparation
(iv) the presence of a wide array of worm antigens, e. g. in a
homogenate, dissipated the host immune response and masked
the presence of the protective antigens possibly as a result of
antigenic competition
(v) the route of antigen administration was the crucial factor that
militated against the induction of functional immunity rather
than the antigens themselves
(vi) the duration of antigenic stimulation was not long enough and a
longer period. analogous to that required for the development of
immunity from an enteric H. diminuta infection, was needed
(vii) the regimes of vaccination described were conducive to the
induction of tolerance.
To elucidate the validity of these assumptions, experiments were
carried out with live worm antigens. The rationale behind each
approach is described separately in the text. Strobilate a-day-old
worms. apparently capable of surviving for appreciable periods of
time when implanted subcutaneously or intraperitoneally, did not
immunize mice against challenge. Implantation of a strobilate 8-day- day old
worm surgically into the duodenum conferred only weak protection.
The in vivo process of excystation, which is by passed when immunization
is performed by implantation of worms directly into the
duodenum, had no influence on the ability of the worm to stimulate
immunity. The se findings suggest that the failure to induce strong
immunity by parenteral implantation of a live a-day-old was possibly due to -the fact that the 8-day- old worm is, in itself, inefficient in
inducing a pronounced protective response against challenge, even
when presented enter ally • The fact that a weak protective response
was induced by the intraduodenal administration of the 8-day-old worm
and not by parenteral implantation of the se worm s suggests that the
enteric route is more efficient in the induction of functional immunity
against the tapeworm than either the subcutaneous or intraperitoneal
routes. In other experiments it was established that the young worm
is more efficient in the stimulation of protective immunity against
challenge than older worms. It is of interest that the older worms,
when implanted surgically into the duodenum, pre sent the host with
significantly larger amounts of strobili antigens per unit time than do
the younger ones. This observation casts doubt on the significance
of the strobila as the major source of H. diminuta protective antigens .
The logical explanation for the failure to immunize mice by vaccination
with the killed worm antigens is that this is possibly because the
antigens used were derived mainly from strobilar tis sue obtained from
worms even older than the 8-day-old parasites whose poor immunizing
potential was demonstrated.
Live excysted worms, which provide only scolex and neck antigens J
were capable of inducing a protective response when administered
intraperitoneally. Irradiated worms, incapable of growing strobilae,
were as immunogenic as worms of the same age which were not
irradiated. Immunization of mice with an irradiated vaccine is advantageous
in the sense that the immunizing infection can be denoted as
self-limiting resulting in the prevention of propagation of the parasite
to the intermediate host, at a time when specific protective immunity
is raised in the definitive host.
Two independent investigations were undertaken to locate the origin
of H. diminuta protective antigens. The technique s of chemical
abbreviation of immunizing infections and irradiation were used for
this purpose. The re suits provided evidence that the induction of
functional immunity against H. diminuta in mice is independent of the
presence of a strobila: is determined by the duration of an antig e nic
stimulus deriving from the scolex and/or neck regions. The degree
of this immunity is also determined by the number of worms in the
immunizing infection. The conclusions drawn from the present
investigation as to the origin of H. diminuta protective antigens and
the immunogenic potential of irradiated worms are at variance with
those reached by other investigators.
In the second part of this thesis the mechanism of the immunologically based
rejection of Raillietina cesticillus from chickens was investigated.
Chickens whose ability to produce antibodies was
abrogated by bur sectomy and irradiation developed protective immunity
against the tapeworm as did the controls with specific anti-worm
antibodies in their sera. It is suggested that antibody is not
the crucial component of the mechanism affecting the growth and
development of R. cesticillus in the immune chicken
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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