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NAME |
Investigators |
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01-R-2003 |
Antimicrobial activity
of cationic peptides derived from tropical snake venoms |
“Bruno Lomonte - CR”
<blomonte@cariari.ucr.ac.cr>
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“Silda Larios - NI” <slarios@unanleon.edu.ni>
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“Andrzej Tarkowski -
SWE” <Andrej.Tarkowski@rheuma.gu.se>
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Myotoxic phospholipases A2 (PLA2s), also
known as myotoxins, present in the venom of the snake Bothrops asper
from Costa Rica, efficiently kill several types of bacteria in vitro
(Ref. 1). This bactericidal action does not depend on the catalytic
activity of the toxins, since it was demonstrated that an
enzymatically-inactive Lys-49 variant (myotoxin II) exerts identical
actions on bacteria as its enzymatically-active Asp-49 counterpart (myotoxin
III). A 13-mer synthetic peptide, corresponding to the residues
115-129 of myotoxin II, at its C-terminal loop, reproduces the
bactericidal action of the whole protein (Ref. 1). The goals of this
project are to further characterize the bactericidal activity and
antimicrobial spectrum of a variety of venom myotoxins isolated from
different snake species, and particularly of their corresponding
cationic C-terminal peptides. A set of peptide variants will be
studied with the aim of defining the relevant structural determinants
for their antimicrobial activity, and their spectrum against different
microorganisms. The best peptide will be selected on the basis of
highest bactericidal activity with lowest toxicity to eukaryotic
cells, and then its in vitro and in vivo antimicrobial efficacy
against experimental bacterial infections in mice will be evaluated.
The possible anti-endotoxic effects of the peptides will also be
evaluated, both in macrophage cultures, and in mice. |
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02-N-2003 |
Pharmacokinetics of
antivenoms in rabbits envenomated with Bothrops asper venom:
towards a more rational therapy of snakebite envenomation in Central
America |
“José María Gutiérrez –
CR” <Jgutierr@icp.ucr.ac.cr>,
<jgutierr22@hotmail.com>
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“Patricia Saravia Otten
- GT” <Patriciaso@hotmail.com>,
<Patricia.Saravia@mtc.ki.se>
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“Monica Thelestam -
SWE“ <Monica.thelestam@mtc.ki.se>
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The
treatment of snakebite envenomations is based on the intravenous
administration of antibodies or antibody F(ab’)2 or Fab
fragments. It has been shown that these molecules have different
pharmacokinetics in normal animals; however, little is known on their
pharmacokinetics in envenomated animals. It is hypothesized that
the drastic hemodynamic alterations induced by crotaline snake venoms
affect the pharmacokinetics of antivenoms. The present project
will compare the most important pharmacokinetic parameters of
antivenoms made of whole IgG molecules, F(ab’)2 fragments
and Fab fragments in normal rabbits and in rabbits envenomated with
Bothrops asper snake venom. In addition, the effect of the
various types of antivenoms in the toxicokinetics of B. asper
venom will be assessed, as a way to characterize the mechanisms by
which antivenoms neutralize venom components in vivo. Finally,
the elimination of venom-antivenom complexes by macrophages will be
studied in vitro. Since current antivenom therapy, including the
selection of the best type of antibody fragments for treatment, is
largely empirical, this project pretends to establish a more rational
basis for the design of therapeutic protocols in the treatment of
envenomations by B. asper, the most important poisonous snake
in Central America. |
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03-N-2003 |
Human Cytomegalovirus
DNA in plasma as a predictive marker of disease and cell tropism. |
“Libia Herrero –
Uribe - CR” <lherrero@racsa.co.cr>
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“Anabelle Ferrera Boza
- HN” <anabelle@gbm.hn>
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“Sara Mercedes
Ahumada-Ruiz - PA”
<sahumadaruiz@hotmail.com>
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“Maria Brytting - SWE”
<Mia.Brytting@smi.ki.se>
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In
Central America the medical field has been dependent on the knowledge
generated in the industrialized world. This fact is contradictory
since the medical facilities, quality of life and most important of
all, the high parasite load at which people from the tropics are
expose to, should make a very important difference in the relationship
between the parasite and its host. A previous study in the Area has
shown that the detection of HCMV DNA in plasma of healthy individuals
is high and in consequence it is not predictive of disease as has been
found in the industrialized world. This study intents to evaluate the
predictive value of HCMV DNA in plasma of healthy individuals in
Central America and to determine genotype diversity during
latent infection as well as cell tropism.
A follow
up study during two years will be done in twenty healthy students of
the Universities who are not involved in health professions or work in
microbiological laboratories and are serologically positive for HCMV
and a cross sectional study of twenty AIDS patients with CMV disease
based on medical criteria who are in control but have not received any
antiviral treatment according to hospital protocols. Peripheral blood
leukocytes (PBL), plasma, pharyngeal swabs and urine samples will be
taken to determine genotypes diversity and cell tropism. To compare
the predictive disease value of HCMV infection in healthy individuals,
plasma viral load and PBL antigenemia will be used. To establish a
more strict criteria about the predictive value of DNA in plasma,
determination of HCMV DNA load in individuals with latent and clinical
HCMV disease will be performed. Genotypes will be
determined by the Restriction Enzyme Fragment Length Polymorphism.
Viral load and sequencing of samples will be performed. The
results we expect is that detection of HCMV DNA in plasma will not be
important for the prediction of HCMV disease but viral DNA load will.
Since this molecular method is very expensive and time consuming, we
expect that antigenemia will be a better indicator of disease to use
in the Central America area. |
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04-N-2003 |
Characterization of
enterotoxigenic Escherichia coli (ETEC) isolates from Guatemala
and Costa Rican children. |
“Ximena Cortés Bratti
- CR” <ximenacortesbratti@yahoo.com>
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“Olga R. Torres
- GT” <otorres@incap.ops-oms.org>
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“Ann-Mari
Svennerholm - SWE”
<ann-mari.svennerholm@microbio.gu.se>
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In the developing world, the annual burden
of diarrhea is estimated to be 1.5 billion episodes among children
less than 5 years of age 1,2. Enterotoxigenic Escherichia coli is the
most frequently isolated enteropathogen in community-based studies.
Besides being well recognized as a major cause of acute childhood
diarrhea ETEC is also an important etiologic agent of traveler’s
diarrhea 4,5,6. Diarrhea remains an important problem in Central
America, however with few exceptions there is little information about
the importance of ETEC. The evidence on the relative involvement of
this pathogen in the etiology of diarrheal diseases has been limited
due to difficulties in its detection. The general objective of this
proposal is to determine the prevalence and characterization of
clinical isolates of ETEC in Guatemala and Costa Rica. An on-going
study in Guatemala will be used as a base to standardized methodology
for the detection of heat stable toxin (ST), heat labile toxin (LT)
and colonization factors(CFs). We aim to obtain epidemiological
information regarding ETEC distribution as well as information on the
variability of toxin and CFs profiles in the circulating strains
associated to diarrhea. |
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05-N-2003 |
Multi-drug resistant
Gram positive bacteria in Central America |
“Mercedes Cáceres -
NI” <mcaceres@unanleon.edu.ni>
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“Silvio Vega
- PA” <silviove@yahoo.com>
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“Rosario Achí
- CR” <machi@cariari.ucr.ac.cr>
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“Ana Berta Cañas
- ELS” <abcanas@yahoo.com>
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“Inger Kuhn - SWE” <Inger.kuhn@mtc.ki.se>
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The
continuing emergence and spread of antimicrobial resistance is a major
global public health problem. One main reason for the observed
increase in resistance is the uncontrolled and excessive antibiotic
use. Disregarding the problem of antibiotic resistance leads not only
to unfavorable medical consequences, but also to substantial
ecological and economic consequences (1) There is limited
information available regarding this very important problem in
developing countries. The
overall purpose of this research project is to gain a better
understanding of the incidence and spread of antibiotic
resistance in Central-America through the establishment of
a regional antimicrobial resistance surveillance system.
The specific aims to years 2004-2005 are: a) To investigate
the occurrence in four Central-American countries of multi-drug
resistant gram positive bacteria; b) to study the
diversity of the drug resistant strains in order to determine
whether resistance is due to dissemination of resistant strains or to
spread of resistance genes; and c) to study the
association between the use of antimicrobials and the prevalence
of antibiotic resistant bacteria. These
aims will be accomplished by collection of multi-resistant
strains and epidemiological data from hospitals and communities
in the countries included in this study. Resistance will be
determined using disk diffusion and E-test, and the
diversity of resistant strains will be determined using biochemical
fingerprinting (the PhP system).
Standardization and quality control protocol will be developed under
the responsibility an Antimicrobial working group organized
by researchers from the universities of Nicaragua, Panama, El
Salvador, Costa Rica and the Karolinska Institutet, Sweden with
the economical support of NETROPICA. |
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06-R-2003 |
Clinical,
epidemiological and seroepidemiological aspects of shigellosis. |
“Rosario Achí - CR” <machi@cariari.ucr.ac.cr>
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“Josefa
Adilia Moran Lemus -
ELS” <josefamoran@hotmail.com>,
<jmoran@biblio.ues.edu.sv> |
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“Mercedes Cáceres -
NI” <mcaceres@unanleon.edu.ni>
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“Silvio Vega
- PA”
<silviove@yahoo.com>
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“Rodolfo Peña
Garcia - NI” <rodolfo.pena@epiph.umu.se>,
<rpena@unanleon.edu.ni> |
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“Peter Allebeck - SWE”
<Peter.Allebeck@socmed.gu.se> |
|
Shigellosis plays an important role in morbidity and mortality in
developing countries and is still an important disease in
industrialized nations. Shigellosis is mainly prevalent in overcrowded
areas with poor sanitation common in developing countries.
Shigellae are spread by the oral-fecal route from person-to-person.
The transmission is facilitated by the very low infectious dose
(100-500 cfu). It is a disease of the colon, defined as an acute,
severe colitis with fever, tenesmus, abdominal cramps with frequent
small, mucoid depositions containing visible blood and leukocytes.
Our previous results confirmed that shigellosis is rather prevalent
particularly among poor, urban groups of Costa Rica. The present study
shows that Shigella sp. is also frequently associated to severe
diarrhea in children from San Salvador, Léon and Panamá. For
that reason, we want to continue to investigate the clinical aspects
of Shigellosis, its prevalence and the seroprevalence and in
particular we aim to concentrate our efforts on epidemiological
studies on diarrhea and shigellosis in Central America. It is
also expected to continue to improve the diagnostic methods
(conventional and molecular Biology) to detect Shigella from stool
specimens, water and perhaps food samples also. The reason to apply
for a renewal of the present project is mainly due to: 1) The
successful results of present collaboration in general, 3) Our
findings at present, 3) In particular due to the present research
activities on community surveys on diarrhea and shigellosis. Knowledge
about occurrence of diarrhea is of great importance for the purpose of
prevention, adequate treatment and follow up of health services. |
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07-R-2003 |
Biogeographical
approach to the study of Triatoma dimidiata populations in
Central America. |
“Maria Carlota Monroy
Escobar - GT” <Carlota.Monroy@ebc.uu.se>,
<carlotamonroy@yahoo.com> |
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“Francisca Marín Díaz
- NI” <cndr@ibw.com.ni>
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“Carlos Ponce
- HN” <carponce@datum.hn>
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“Rodrigo Zeledon
- CR” <rzeledon@racsa.co.cr>
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“Thomas G.T. Jaenson
- SWE” <Thomas.Jaenson@ebc.uu.se>
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This is a renewal proposal that aims to
continue to previous works supported by Netropica.
Morphometric and genetic characterization of different Central
American populations of Triatoma dimidiata has shown a very
interesting pattern of association between populations (7,8) that
proves to be highly related to the geographical distribution as well
as to ecotope origin (4, LENAP-unpublished data). In our proposal we
would like to continue the study of populations of T. dimidiata in
relation to the geographical history of the Central American region.
Eight morphotectonic units have been defined in the geological history
of Central America (lowland of the Atlantic coast, volcanic chain in
the Pacific coast, highland of North Central America, low lands of the
Pacific coast and some other (1,2,9). We would like to search for a
relation between the morphotectonic units and the characterization of
the populations by morphometrics analysis and RAPD-PCR technique. The
aim of the study is to understand the actual state of the populations
of T. dimidiata in relation to the geological structuring of the
Central American region. The relation of geographical-morphotectonic
units and the genetic-morphometric characterization of the population
could clarify our understanding of the origin of the populations in
the region, inferring which are the oldest, what were their past
movements and where are the recently occupied geological areas of the
species. This information could be very helpful in the actual Central
American Initiative for the control of the Chagas disease vectors by
indicating how T. dimidiata has behaved in the past and by predicting
the patterns and trends in the structure of its populations. Due to
the high polymorphism presented by this species reflected by diverse
behavioral and epidemiological observations in different regions it is
important to conduct these types of studies, which also evaluate the
vectorial capacities of the vector in the Central American area. The
movement of vectors between sylvatic and domestic ecotopes poses a
serious impediment to an effective interruption of the disease cycle.
With this collaborative research we aim to understand the populations
dynamics of the species. |
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08-R-2003 |
Preparation and
Characterization of Monoclonals Antibodies Against a Trypanosoma
rangeli Sialidase |
“Azael Saldaña Patiño
- PA” <azasal@hotmail.com>
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“Octavio Elias Sousa
Pitti - PA” <osousa@ancon.up.ac.pa>
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“Juan Miguel Pascale
- PA “ <jmpascal@yahoo.com>
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“María del Rosario Palma
- NI” <paramed@unanleon.edu.ni>
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“Anders Örn -
SWE “ <anders.orn@mtc.ki.se>
& “Bjorn Andersson - SWE” <bjorn.andersson@cgb.ki.se>
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The
epimastigote stage of Trypansoma rangeli expresses a sialidase
which is released into culture medium.
 In
contrast to a homologous enzyme found
in T. cruzi,
the biological, immunobiochemical and molecular properties of the
T. rangeli sialidase remain to be clarified. In preliminary
reports,
we determined antigenic cross-reaction between a T. rangeli
released sialidase (TrSialr) and a polypeptide of 70 KDa found in
T. cruzi parasites (TcSialL).
Moreover, we purified the T. rangeli somatic sialidase (TrSials)
by immunoprecipitation and determined a good immune recognition of
this antigen by sera from mice and humans infected with T. cruzi.
In addition, an apparently related sialidase fraction (Trp19) is a
specific marker for T. rangeli isolates. Thus, the study of
the antigenic/molecular relationships between TrSials, TrSialr, Trp19
and TcSialL could help in the understanding of the biological role and
immunological characteristics of these proteins. We propose here to
construct a T. rangeli gene expression library in order to
study the TrSials and Trp15 antigenic proteins. Also, to
evaluate the TrSials recombinant protein in the serology of Chagas’
disease and to investigate the use of the Trp19 gene as a specific
molecule for identification and characterization of T. rangeli
isolates. |
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09-R-2003 |
MOLECULAR EPIDEMIOLOGY
AND DRUG-SUSCEPTIBILITY TEST OF Mycobacterium tuberculosis
STRAINS IN HONDURAS, GUATEMALA AND PANAMA |
“Lelany Pineda-Garcia
- HN” <lelanypineda@yahoo.com>,
<lapineda55@hotmail.com>
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“Blanca Samayoa Herrera
- GT” <mosamayoa@guate.net>
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“AMADOR D. GOODRIDGE-JOHNSON
- PA” <agoodridge@senacyt.gob.pa>,
<amadorgj@yahoo.com>
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“SVEN HOFFNER - SWE”
<Sven.hoffner@smi.ki.se>
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Tuberculosis is a major health problem in Central America. The
situation has recently become more severe due to HIV and drug
resistance. An increased knowledge of the transmission of the disease
as well as of the problem of drug resistance is urgently needed. To
scientifically address these questions, Honduras, Guatemala and Sweden
had formed a network on molecular characterization and drug
susceptibility testing of Mycobacterium tuberculosis. Now we
are presenting a continuation and extension of the project including
Panama as new partner. We are planning to study the transmission
dynamics and susceptibility profiles of clinically isolated strains of
M. tuberculosis now circulating in the region, and at the same
time implement important scientific techniques and for the first time
create a M. tuberculosis database in Central America. This
project will support the National Control TB Program in the involved
countries by increasing the understanding of how the TB problem best
is controlled. Aiming at establishing a system for early detection of
drug-resistant tuberculosis, a new technique, the Nitrate Reduction
assay, will be compared to a standard reference technique for
detection of resistance to rifampicin and isoniazid.
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10-N-2003 |
STUDIES ON MOLECULAR
DIVERSITY OF HEPATITIS C VIRUS (HCV) INFECTION IN PAEDIATRIC OUTBREAKS
AND RISK GROUPS IN CENTRAL AMERICA. |
“MARIO
AUGUSTO GONZALEZ-PEREZ -
GT” <maugonzalez@hotmail.com>
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“KIRSTEN A. VISONA - CR” <icmrtlsu@racsa.co.cr>
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“RENE
BERRIOS CRUZ-NI” <rbc20@ibw.com.ni>
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“MATTI SÄLLBERG-swe” <Matti.Sallberg@labmed.ki.se> |
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Nosocomial infection of HCV has been described world-wide and liver
disease outcome has been related to HCV specific genotypes, proposed
as the major determinants of progression from chronic active hepatitis
to cirrhosis. HCV genotype I is related to high viral loads and
frequent severe liver disease. The aim of this project is to
further investigate risk factors involved in an HCV nosocomial
outbreak in Nicaraguan children attending a Haematology-Oncology Unit,
where 53% of 625 children were HCV infected and 91% belonged to
genotype I1. Another study done in a cohort of 120
Nicaraguan haemophiliacs, who only have received local blood products,
also revealed a 53% of HCV infection2. Therefore, to
better determine the risk factors, these patients’ samples will be
further investigated using a genetic approach to determine diversity
by SSCP of the HVR1 and genotype of HCV-NS5 region; a follow up study
of both risk populations will be included. Samples from
different Guatemalan risk-groups and Nicaraguan healthy blood donors
also will be enrolled to further determine the genetic diversity in
the Central American countries. These results might contribute
to implement better preventive measures related to HCV outbreaks,
dissemination to the general population and to generate additional
information about the HCV diversity in this area. |
