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At least 973 records · Page 54Linked to original sources
PubMed2005

Electrosensory interference in naturally occurring aggregates of a species of weakly electric fish, Eigenmannia virescens.

The detection and identification of behaviorally relevant signals in the presence of competing signals in the environment is a major challenge of animal sensory systems. In weakly electric fish such as Eigenmannia virescens, the interactions between the autogenous electric field and the electric fields of nearby conspecifics can have profound effects on the perception of other behaviorally relevant electrosensory information. To better understand the natural signals that the nervous system of Eigenmannia experiences during the processing of electrosensory information, we examined the electrosensory milieu of Eigenmannia in the wild and in the laboratory. Recordings of the electric fields of Eigenmannia were made in 'black' and 'white' waters near the Napo River in eastern Ecuador. Fourier analysis revealed that Eigenmannia typically experience the electric fields of three to five conspecifics during the day and night in each habitat. The median difference in electric organ discharge frequencies between nearby Eigenmannia during the day was 23 Hz in black water habitats, 41 Hz in white water, and 37 Hz at night in both habitats: these signals are known to activate tuberous electroreceptors and downstream CNS circuits. There was no correlation between the number of individual Eigenmannia detected at recording sites and electric organ discharge frequencies. Further, Eigenmannia apparently do not maximize the frequency differences between conspecifics. In laboratory studies fish were preferentially observed in aggregates of two fish or more. Aggregate sizes observed in the laboratory were similar to those in the wild.

Animal Communication↗
PubMedDate not supplied

Naxos disease and Carvajal syndrome: cardiocutaneous disorders that highlight the pathogenesis and broaden the spectrum of arrhythmogenic right ventricular cardiomyopathy.

Naxos disease is a recessive association of arrhythmogenic right ventricular cardiomyopathy (ARVC) with wooly hair and palmoplantar keratoderma or similar skin disorder. The clinical and histopathological spectrum of heart disease, molecular genetics and genotype-phenotype correlation are reviewed in 22 affected families with this cardiocutaneous syndrome reported in the literature from Greece, Italy, India, Ecuador, Israel and Turkey. All patients had the hair and skin phenotype from infancy and developed ARVC by adolescence. Mutations in genes encoding the cell adhesion proteins piakoglobin and desmoplakin that truncate the proteins at the C-terminal domains were identified to underlie this syndrome. A particular mutation in Ecuadorian families that truncates the intermediate filament-binding site of desmoplakin results in a variant of Naxos disease with predominantly left ventricular involvement, early morbidity and clinical overlapping with dilated cardiomyopathy (Carvajal syndrome). A lethal autosomal recessive cardiocutaneous syndrome of Poll Hereford calves has been reported in Australia sharing similarities with the human syndrome reviewed here with respect to hair and cardiac phenotype. The cardiomyopathy in Naxos cardiocutaneous syndromes presents with increased arrhythmogenicity and variable left ventricular involovement and is characterized histologically by myocardial loss with fibrofatty or fibrous replacement at subepicardial and mediomural layers. The clinical heterogeneity and tissue characteristics in this cell-adhesion cardiomyopathy might be mutation specific and leads to consideration that the spectrum of ARVC should be broadened.

Abnormalities, Multiple↗
PubMed2005

Design of PREVENCION: a population-based study of cardiovascular disease in Peru.

Latin America is undergoing the epidemiologic transition that occurred earlier in developed countries, and is likely to face a gigantic epidemic of heart disease in the next few years unless urgent action is taken. The first essential component of any effective cardiovascular disease (CVD) control program is to establish reliable estimates of cardiovascular disease-related morbidity and mortality. However, such data from population-based studies in Latin America are still lacking. In this paper, we present the design and operation of PREVENCION (Estudio Peruano de Prevalencia de Enfermedades Cardiovasculares, for Peruvian Study of the Prevalence of Cardiovascular diseases). PREVENCION is an ongoing population-based study on a representative sample of the civilian non-institutionalized population of the second largest city in Peru. Its population is comparable to the rest of the Peruvian urban population and closely resembles other Latin American populations in countries such as Bolivia and Ecuador. Our study will contribute to the enormous task of understanding and preventing CVD in Latin America.

Cardiovascular Diseases↗
PubMed2005

Epidemiology and clinical characteristics of classic Kaposi's sarcoma, seroprevalence, and variants of human herpesvirus 8 in South America: a critical review of an old disease.

OBJECTIVE: To review the current South American literature on classic Kaposi's sarcoma (KS) and human herpesvirus 8 (HHV-8), and point the way for studies that still need to be performed. MATERIALS AND METHODS: The authors performed an exhaustive search in LILACS, SCIELO and PUBMED databases for classic KS and HHV-8 in South America. The relevant material was evaluated and reviewed. RESULTS: More than 250 cases have been reported with three big case series (Argentina, Colombia and Peru). The classic KS form seen in Colombia resembles the type of disease seen among African communities; the same unusual presentation with confluent exophytic nodules or eroded lesions has been noticed in Peru. Low rates of HHV-8 antibodies have been found in blood donors from Chile, Argentina and Brazil (3%, 4%, 2.8-7.4%, respectively); whereas high rates of HHV-8 antibodies have been found in Amerindians from Brazil and Ecuador. Five specimens from Argentina were subtyped: (three classic KS and two AIDS KS); the identified strains fell into subtypes A and C. AIDS-related KS specimens from Brazil and Venezuela were subtyped: (43 and nine respectively); analysis grouped them predominantly into subgroups A, B and C. A new HHV-8 subtype E was found endemic in Brazilian and Ecuadorian Amerindians. In French Guiana ten endemic KS and six AIDS-related KS specimens were subtyped; analysis grouped them predominantly into subgroups A, B and C. CONCLUSION: Classic KS in South America has a very similar clinical presentation but not the same as the classic KS variety described in the Mediterranean. Initial seroprevalence studies performed in the general population and in blood donors showed low seroprevalence of HHV-8, whereas high seroprevalence rates were seen in Amerindian population. The existing serological assays, nonetheless, need to be further refined, and new assays need to be developed. Finally, the key to understanding the precise molecular epidemiology and phylogenetic distribution of HHV-8 in South America would be to perform more subtyping of classic KS cases.

AIDS-Related Opportunistic Infections↗
PubMed2006

CFTR gene analysis in Latin American CF patients: heterogeneous origin and distribution of mutations across the continent.

BACKGROUND: Cystic Fibrosis (CF) is the most prevalent Mendelian disorder in European populations. Despite the fact that many Latin American countries have a predominant population of European-descent, CF has remained an unknown entity until recently. Argentina and Brazil have detected the first patients around three decades ago, but in most countries this disease has remained poorly documented. Recently, other countries started publishing their results. METHODS: We present a compilation and statistical analysis of the data obtained in 10 countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, Mexico, Uruguay and Venezuela), with a total of 4354 unrelated CF chromosomes studied. RESULTS: The results show a wide distribution of 89 different mutations, with a maximum coverage of 62.8% of CF chromosomes/alleles in the patient's sample. Most of these mutations are frequent in Spain, Italy, and Portugal, consistent with the origin of the European settlers. A few African mutations are also present in those countries which were part of the slave trade. New mutations were also found, possibly originating in America. CONCLUSION: The profile of mutations in the CFTR gene, which reflects the heterogeneity of its inhabitants, shows the complexity of the molecular diagnosis of CF mutations in most of the Latin American countries.

Africa↗
PubMed2005

Cocaine distribution in wild Erythroxylum species.

Cocaine distribution was studied in leaves of wild Erythroxylum species originating from Bolivia, Brazil, Ecuador, Paraguay, Peru, Mexico, USA, Venezuela and Mauritius. Among 51 species, 28 had never been phytochemically investigated before. Cocaine was efficiently and rapidly extracted with methanol, using focused microwaves at atmospheric pressure, and analysed without any further purification by capillary gas chromatography coupled to mass spectrometry. Cocaine was reported for the first time in 14 species. Erythroxylum laetevirens was the wild species with the highest cocaine content. Its qualitative chromatographic profile also revealed other characteristic tropane alkaloids. Finally, its cocaine content was compared to those of two cultivated coca plants as well as with a coca tea bag sample.

Coca↗
PubMed2006

Trichoderma theobromicola and T. paucisporum: two new species isolated from cacao in South America.

Trichoderma theobromicola and T. paucisporum spp. nov. are described. Trichoderma theobromicola was isolated as an endophyte from the trunk of a healthy cacao tree (Theobroma cacao, Malvaceae) in Amazonian Peru; it sporulates profusely on common mycological media. Trichoderma paucisporum is represented by two cultures that were obtained in Ecuador from cacao pods partially infected with frosty pod rot, Moniliophthora roreri; it sporulates sporadically and most cultures remain sterile on common media and autoclaved rice. It sporulates more reliably on synthetic low-nutrient agar (SNA) but produces few conidia. Trichoderma theobromicola was reintroduced into cacao seedlings through shoot inoculation and was recovered from stems but not from leaves, indicating that it is an endophytic species. Both produced a volatile/diffusable antibiotic that inhibited development of M. roreri in vitro and on-pod trials. Neither species demonstrated significant direct in vitro mycoparasitic activity against M. roreri.

Base Sequence↗
PubMed2004

Genotypic variation among lineages of Trypanosoma cruzi and its geographic aspects.

Isozyme analysis with 18 enzyme loci was conducted on 146 isolates of Trypanosoma cruzi from Mexico, Guatemala, Colombia, Ecuador, Peru, Brazil, Bolivia, Paraguay and Chile. Forty-four different MLGs (groups of isolates with identical multilocus genotypes) were identified and a phylogeny was constructed. The phylogenetic tree consisted of two main groups (T. cruzi I, T. cruzi II), and the latter was further divided into two subgroups (T. cruzi IIa, T. cruzi IIb-e). Evidence of hybridization between different MLGs of T. cruzi II was found, which means that genetic exchanges seem to have occurred in South American T. cruzi. On the other hand, the persistence of characteristic T. cruzi I and T. cruzi II isozyme patterns in single small villages in Bolivia and Guatemala suggested that genetic exchange is very rare between major lineages. A significant difference in genetic diversity was shown between T. cruzi I and T. cruzi II from several indices of population genetics. Two possibilities could explain this genetic variation in the population: differences in evolutionary history and/or different tendencies to exchange genetic material. Broad-scale geographic distributions of T. cruzi I and T. cruzi IIb-e were different; T. cruzi I occurred in Central America and south to Bolivia and Brazil, while T. cruzi IIb-e occurred in the central and southern areas of South America, overlapping with T. cruzi I in Brazil and Bolivia.

Animals↗
PubMed2005

Lessons from a national survey of Chagas disease transmission risk in Colombia.

In recent years, there has been a revitalization of large-scale programmes to control parasitic disease in developing countries. In 1997, the Governments of Colombia, Venezuela, Ecuador and Peru committed themselves to replicate the cost-effective elimination of Trypanosoma cruzi transmission achieved in the Southern Cone by using insecticides against the domestic triatomine vectors (in combination with blood-bank screening). Central American Governments launched a complementary initiative. All plan to interrupt vectorial transmission throughout the region by 2010 but specific targets are decided nationally. In this article, we highlight the novel approach taken by the Colombian Government for determining the geographic distribution of Chagas disease risk to select where to intervene first.

Animals↗
PubMed2004

The effects of combined aromatase inhibitor and anti-androgen on male territorial aggression in a tropical population of rufous-collared sparrows, Zonotrichia capensis.

Territorial aggression, exhibited by male vertebrates in a reproductive context, is generally thought to be mediated by elevated levels of the gonadal steroid hormone testosterone. Rufous-collared sparrows from Papallacta, Ecuador are only aggressive during the breeding season when plasma testosterone concentrations are elevated. However, previous experiments have determined that during the breeding season testosterone does not increase in response to territorial challenges and testosterone implants do not make males more aggressive. This relationship between testosterone and aggression is different from closely related northern latitude species. We conducted another experiment investigating the role of testosterone in mediating territorial aggression, during the breeding season, in male rufous-collared sparrows. We predicted that blocking the actions of the testosterone would suppress aggression in response to territorial challenges. During the early breeding season males were captured using a simulated territorial intrusion and there was no relationship between time to capture and plasma testosterone, dihydrotestosterone, and corticosterone concentrations. Individual males were then implanted with both the aromatase inhibitor ATD and the anti-androgen Flutamide or empty implants as a control. After one week, birds were challenged with a simulated territorial intrusion and the aggressive responses measured. There were no differences in individual behavioral responses (number of songs, flights, closest approach, or time within 5 m) or overall aggression between the two groups. Androgen levels were elevated, post-implant, in the experimental group suggesting that the treatment was successful by blocking the negative feedback system. We conclude that pharmacologically inhibiting testosterone during the breeding season does not affect territorial aggression in these birds.

Aggression↗
PubMed2004

Perceived barriers and benefits to cervical cancer screening in Latin America.

BACKGROUND: This article describes the results of studies on the barriers and benefits of cervical cancer screening from the perspective of women, men, and health providers in five Latin American countries and compares them to other findings from the literature. METHODS: Five separate qualitative studies (focus groups and interviews) were conducted among low-income women in Venezuela, Ecuador, Mexico, El Salvador, and Peru regarding barriers and benefits of cervical cancer screening. Views from health providers and men were also included. RESULTS: The main barriers identified by all participants are accessibility and availability of quality services, facilities that lack comfort and privacy, costs, and courtesy of providers, which interact with poor service delivery. Barriers that pertain to women's beliefs are anxiety borne by women awaiting test results, associated with negligence and fear of cancer (although not to a particular cancer or a particular procedure). Benefits of screening are peace of mind and being in control of their health, which then enable other life activities to continue unhindered. CONCLUSIONS: Except for the accessibility and availability of quality services, these results are consistent with findings from other studies in developed and developing countries. Barriers could be lifted if health service delivery was enhanced, for instance, through quality improvement techniques that are available at low cost. Women's anxiety over test results still needs to be further assessed to devise risk communication strategies that take into account broader cultural frameworks. It is to be noted that such strategies should permeate the way health services are provided for cervical cancer prevention regardless of the specific test used. Vulnerability perceived by low-income women with respect to their capacity to cope with diseases and trust the health services and how this affects their perceptions of risk and their behaviors have not been studied as yet.

Adult↗
PubMed2002

Magnetic resonance imaging in the diagnosis of subretinal cysticercosis.

PURPOSE: To report a case of ocular cysticercosis and associated magnetic resonance imaging (MRI) findings. DESIGN: Interventional case report. METHODS: A 56-year-old woman from Ecuador presented with decreased vision and an exudative retinal detachment in the left eye. Subretinal cysticercosis was suspected. RESULTS: In the left eye, a subretinal cyst evident on fundus examination was investigated with B-scan ultrasonography. Ultrasonography showed a cystic structure, and MRI of the orbit confirmed the suspicion for cysticercosis. Magnetic resonance imaging of the brain also revealed a small parenchymal lesion in the left occipital lobe of the brain. CONCLUSIONS: Magnetic resonance imaging is a useful adjunct to B-scan ultrasonography in the diagnosis of ocular cysticercosis. Magnetic resonance imaging is superior to computed tomography in the demonstration of cystic structures in the eye and central nervous system. This finding has important therapeutic implications, as any viable cysticercus in the eye or cerebral parenchyma can be treated surgically or medically, respectively.

Cysticercosis↗
PubMed2002

Latitudinal variation in plasma testosterone levels in birds of the genus Zonotrichia.

Birds breeding in northern latitudes generally have elevated plasma testosterone levels throughout the breeding season with a peak at the onset of the breeding season. In contrast, tropical birds tend to have extremely low plasma testosterone levels year round with only a slight increase during breeding. While these patterns have been consistent in the species investigated, closely related species have not been investigated across a range of latitudes. Birds of the genus Zonotrichia present an ideal opportunity to investigate latitudinal variation in plasma testosterone levels as breeding populations occur from northern Alaska to southern Argentina. We studied three taxa of Zonotrichia: (1) Gambel's white-crowned sparrows, Zonotrichia leucophrys gambelii, breeding at high latitude in northern Alaska, (2) Puget Sound white-crowned sparrows, Z. l. pugetensis, breeding at mid-latitude in Washington state, and (3) an equatorial population of the rufous-collared sparrow, Z. capensis, in Ecuador. To compare both baseline breeding and maximal testosterone levels, males from the three taxa were either bled immediately upon capture during the breeding season or first challenged with gonadotropin-releasing hormone (GnRH) and then bled. As a control, another group of birds experienced a saline challenge. Two-way ANCOVA, with treatment and taxa as factors and testis volume as a covariate, showed a significant effect of treatment on plasma testosterone levels. There was also a significant interaction between taxa and treatment. Contrary to expectations, the equatorial species exhibited greater plasma testosterone levels in response to the GnRH challenge than the high latitude species. There were no differences between the mid- and high-latitude species. The equatorial species had the smallest average testis size and within each taxa there were no relationships between plasma testosterone and testis size. These data suggest that latitudinal clines in plasma testosterone levels in Zonotrichia do not follow previously described patterns and that tropical birds can have levels of testosterone similar to northern latitude species.

Animals↗
PubMed2001

Early immunodiagnosis of fasciolosis in ruminants using recombinant Fasciola hepatica cathepsin L-like protease.

A diagnostic ELISA with recombinant Fasciola hepatica cathepsin L-like protease as antigen was developed to detect antibodies against F. hepatica in sheep and cattle. The recombinant cathepsin L-like protease was generated by functional expression of the cDNA from adult stage F. hepatica flukes in Saccharomyces cerevisiae. Specificity and sensitivity of the cathepsin L enzyme-linked immunosorbent assay (ELISA) was assessed using sera from sheep and calves experimentally or naturally mono-infected with F. hepatica and six-seven other parasites. The sensitivity of the cathepsin L ELISA for sheep and cattle sera was 99.1 and 100%, respectively. In the experimental setting with established mono-infections, the specificity of the cathepsin L ELISA was 98.5% for cattle sera and 96.5% for sheep sera. In experimentally infected cattle and sheep, the first detection of F. hepatica-specific antibodies appeared first between 5 and 7 weeks post-infection, but depended on the infectious dose of F. hepatica. In ELISA the detection preceded first detection of the infection based on egg counts and remained detectable till at least 23 weeks after a primary F. hepatica infection. Detection of Fasciola gigantica infections was similar to detection of F. hepatica. The first detection occurred at week 5 and signals persisted for at least 20 weeks. All sera from naturally F. hepatica infected sheep were seropositive in the cathepsin L-like ELISA. The relevance of this ELISA format was also evaluated using sera from naturally infected cattle in the Netherlands, Ecuador and Vietnam and compared with results from egg-counts. For the latter two endemic areas with mixed parasitic infections the 'apparent' sensitivity of the cathepsin L ELISA was calculated for all serum samples together to be 90.2%. The 'apparent' specificity under these conditions was calculated to be 75.3%. In cattle, the cathepsin L ELISA was superior to the concurrently evaluated peptide ELISA format using a single epitope as the antigen both in controlled natural infections as well as in infections in endemic areas. The present ELISA-format contributes a relatively sensitive and reliable tool for the early serodiagnosis of bovine and ovine fasciolosis.

Animals↗
PubMed1998

South American Monogenea--list of species, hosts and geographical distribution.

Five-hundred and twenty-three species of monogeneans have been recorded in South America: 43 from Argentina, one from Bolivia, 252 from Brazil, 29 from Chile, 15 from Colombia, eight from Ecuador, 26 from Falkland and Patagonian regions, four from French Guyana, 11 from Galapagos, two from Guiana, four from Paraguay, 92 from Peru, 16 from Uruguay and 20 from Venezuela. A list of these species with hosts and geographical distribution is presented.

Animals↗
PubMed1997

Normal auditory brainstem and cochlear function in extreme pediatric plumbism.

Lead (Pb) intoxication in children has been associated with encephalopathy, sensory and cognitive impairments. We investigated the prevalence and neuro-sensory effects of Pb exposure in children living in Andean villages of Ecuador with high Pb contamination from discarded automobile batteries used in the local ceramics glazing industry. Venous blood samples were collected from 107 children in the Pb glazing area and from 39 children living in a geographically distant area with no known Pb contamination and measured for blood lead (PbB) levels. Auditory brainstem responses (ABR) and audiological/otological tests were conducted on children in the Pb-Glazing Group. The median PbB level for children in the Pb-Glazing Group was 40.0 microg per dl (range: 6.2-128.2 microg per dl) and for the non Pb-Glazing Group 6.0 microg per dl (1.9-18.0 microg per dl). The differences in PbB levels for children in the study and control areas were statistically significant (t-test, P<0.0001). ABR tests on the Pb-Glazing Group indicated normal wave latencies and neural transmission times, and no statistical correlation between PbB level and interpeak latencies. Audiological tests showed normal cochlear function and no statistical relation between auditory thresholds and PbB level. Contrary to prevailing assumptions, elevated PbB levels in children do not invariably impair auditory brainstem neural transmission or sensory-neural cochlear function, both of which have been implicated as significant contributors to the neurodevelopmental disabilities associated with childhood plumbism.

Adolescent↗
PubMed1997

Growth hormone insensitivity.

Growth hormone insensitivity (GHI) may be primary, caused by defects in the GH receptor, or further along the GH-insulin-like growth factor-I (IGF-I) axis, or secondary, resulting from a variety of illnesses or malnutrition affecting various steps in the pathway from the GH binding to IGF-I action. GH receptor deficiency, although rare, with only 229 cases reported, is the most common cause of primary GHI. Most patients are of Jewish, Arab, or other Mediterranean origin, the largest cohort being Catholics of Jewish origin coming from a small area in southern Ecuador, who account for one third of known cases. This large cohort has provided insight into the clinical features, growth characteristics, biochemical features, and effects of treatment with recombinant IGF-I. The Ecuadorian patients share a splice site mutation in the GH receptor gene with at least one Israeli patient of Iberian origin; 27 other mutations and a major deletion have been described in other affected patients.

Female↗
PubMed2003

Purine alkaloids in Paullinia.

Among the few purine alkaloid-containing genera consumed as stimulants, Paullinia is the least investigated with respect to both chemotaxonomy and within-the-plant allocation of caffeine and its allies. Since purine alkaloids (PuA) have been proved to be valuable marker compounds in chemotaxonomy, 34 species of Paullinia and related genera were screened for them, but only one, P. pachycarpa, was positive in addition to the already known P. cupana and P. yoco. The PuA allocation in P. pachycarpa was examined and found to be restricted to theobromine in the stem, leaves and flowers. Moreover, the theobromine concentration in the stem cortex increased significantly towards the base of the plant. Since the stem cortex of P. yoco is traditionally used by the natives of Colombia and Ecuador to prepare a caffeine-rich beverage, we suspected that within the genus Paullinia the PuA are preferentially allocated to the older parts of the stem and not to young shoots like e.g., in the coffee plant (Coffea spp.). Indeed, the axis (greenhouse) of P. cupana (guaraná), known for its caffeine-rich seeds, exhibited a basipetal PuA gradient (0.005-0.145%). Moreover, the analysis of young cortex samples (herbarium) and of one piece of old stem (museum collection) revealed the same for P. yoco, even though we found much less (0.5 vs 2.5%) caffeine in the old cortex as compared to the only two analyses in 1926 of similar material. However, this discrepancy may be explained by the high variability of the PuA pattern we detected among yoco, the diversity of which the Indians take advantage.

Alkaloids↗