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H Perez

Publications and source records attributed to H Perez.

At least 19 recordsLinked to original sources
PubMed2005

The detection and PCR-based characterization of the parasites causing trypanosomiasis in water-buffalo herds in Venezuela.

The usefulness of PCR-based assays for detecting trypanosomiasis in water buffaloes and other livestock was explored, under field conditions, in Venezuela. The sensitivity and specificity of the assays, which were based on established primer pairs (21-mer/22-mer and ILO1264/ILO1265), were evaluated, partly by comparison with the results of parasitological tests (stained bloodsmears and microhaematocrit centrifugation) and immunological assays (IFAT) run in parallel. The optimised PCR-based assays showed a sensitivity of 10 pg DNA. The use of the 21-mer/22-mer primer pair gave a test that was specific for species in the subgenus Trypanozoon (including Trypanosoma evansi), whereas use of ILO1264/ILO1265 produced a test that was specific for T. vivax. The results of a hybridization assay using T. evansi-DNA and T. vivax-DNA probes indicated no cross-hybridization between the T. evansi and T. vivax PCR products.The results of the bloodsmear examinations, microhaematocrit centrifugations (MHC) and IFAT indicated that 23 (6.7%), 39 (11.4%) and 135 (39.5%) of the 342 blood samples investigated (including 316 from water buffaloes) contained trypanosomes, respectively. The results of the PCR-based assays indicated that 68 (19.9%) of the same blood samples contained T. vivax (or at least T. vivax DNA), and that none contained T. evansi or any other member of the subgenus Trypanozoon. For the detection of trypanosomes, the assay therefore appeared almost twice as sensitive as the MHC. These results are the first on the molecular characterization of the trypanosomes infecting water buffaloes in Venezuela. When the results of the MHC (which is the most practical, and frequently used, alternative detection method) were used as the gold standard, the PCR-based assay for T. vivax was found to have 100% sensitivity, 90.4% specificity, a positive predictive value of 0.57, a positive likelihood ratio of 10.45, and a negative likelihood ratio of 0.00. The assay therefore appears a reasonable choice for detecting T. vivax in the mammalian livestock of Venezuela and elsewhere.

Animals↗
PubMed2003

Plasmodium vivax CS peptides display conformational preferences for folded forms in solution.

Spectroscopic techniques have been used to study the conformations of several synthetic peptides with sequences corresponding to the repeat regions of the circumsporozoite proteins of Plasmodium vivax, variants vk-210 and vk-247. As has previously been shown for P. falciparum, turn-like folded conformations are observed, in rapid dynamic equilibrium with extended-chain forms. These results are consistent with the known similarity of the structural, biosynthetic and immunological properties of the circumsporozoite proteins of different plasmodial species. Additionally, the observation of folded conformers provides a rationale for the effectiveness of these peptides as immunogens and potential vaccines.

Amino Acid Sequence↗
PubMed2003

Low-grade parasitaemias and cold agglutinins in patients with hyper-reactive malarious splenomegaly and acute haemolysis.

A cluster of 16 cases of hyper-reactive malarious splenomegaly (HMS) with severe, acute haemolysis, from an isolated, Venezuelan, Yanomami population, was prospectively investigated. Nine (69%) of the 13 HMS sera investigated but only one (7%) of 14 control sera (P < 0.005) contained elevated titres (of at least 1:32) of complement-fixing IgM cold agglutinins (CA). The CA detected had specificity for both the I and i blood-group antigens (with a relative predominance of anti-I) and wide thermal stability. The mean reciprocal CA titre was much higher for the HMS sera than for the control samples (59.16 v. 2.28; P < 0.001). Indirect tests for antiglobulin were positive for two of the 13 HMS cases (but none of 14 controls) investigated; all of the direct tests for antiglobulin gave negative results. The seven HMS cases checked, using an assay based on a nested PCR which amplified species-specific ribosomal sequences from Plasmodium vivax or P. falciparum, each yielded the PCR product that indicated P. vivax infection. However, only six (25%) of the 24 control samples (collected, at the same time as the HMS samples, from asymptomatic adults from the same Yanomami population) were PCR-positive (P < 0.001). In some cases at least, the acute severe episodes of haemolysis occasionally seen in HMS appear to be associated with an auto-immune, cold-agglutinin-mediated response triggered by non-patent parasitaemias.

Adult↗
PubMed2002

Serological evidence for recent exposure to Taenia solium in Venezuelan Amerindians.

This study examined the seroprevalence and serum antibody isotype profile for Taenia solium cysticercosis in an Amerindian community in the Amazonas state of Venezuela. An antigen-trapping enzyme-linked immunosorbent assay (Ag-ELISA) was used to detect viable cysticercosis. Indirect ELISA (Ab-ELISA) and enzyme-linked immunoelectrotransfer blot (EITB) was performed by using antigens prepared from T. solium metacestodes to detect anti-parasite antibodies. The Ag-ELISA and Ab-ELISAs revealed 64.7% and 79.0% seropositivity, respectively, in the Amerindian population. Immunoglobulin (Ig) M was the predominant antibody class, suggesting recent infection. In comparison sera from, clinically defined, hospital neurocysticercosis cases revealed only 27% seropositivity by Ag-ELISA, compared with 86-92% seropositivity by Ab-ELISA, and IgG4 was the predominant antibody subclass detected. The EITB antigen recognition patterns of the hospitalized patients were very similar to that of the Amerindians, confirming exposure to the parasite. These results, combined with the predominance of IgM antibody responses and the marked detection of secreted products of viable parasites, strongly suggest that recent exposure to T. solium had occurred in the Amerindian population.

Adolescent↗
PubMed2000

Overview of some biomedical research projects in tropical medicine conducted at the Instituto Venezolano de Investigaciones Cientificas.

The Instituto Venezolano de Investigaciones Cientificas (IVIC) is a government-funded multidisciplinary academic institution dedicated to research, development and technology in many areas of knowledge. Biomedical projects and publications comprise about 40% of the total at IVIC. In this article, we present an overview of some selected research and development projects conducted at IVIC which we believe contain new and important aspects related to malaria, ancylostomiasis, dengue fever, leishmaniasis and tuberculosis. Other projects considered of interest in the general area of tropical medicine are briefly described. This article was prepared as a small contribution to honor and commemorate the centenary of the Instituto Oswaldo Cruz.

Academies and Institutes↗
PubMed1999

Effects of mild protein prenatal malnutrition and subsequent postnatal nutritional rehabilitation on noradrenaline release and neuronal density in the rat occipital cortex.

There is evidence that severe malnutrition started during gestation and continued through lactation affects adversely the morphologic development of the neocortex leading to increased neuronal cell packing density and decreased dendritic branching. Nevertheless, the effect of purely mild protein prenatal malnutrition on neocortical development remains rather unexplored. This study evaluates the effects of mild protein prenatal malnutrition (8% casein diet, calorically compensated by carbohydrates) and subsequent postnatal nutritional rehabilitation (25% casein diet) on: (i) the potassium-induced release of [(3)H]-noradrenaline (NA) in occipital cortex slices obtained from 1- and 22-day-old pups; and (ii) the packing density of neurons in lateral, dorso-lateral and dorsal regions of the occipital cortex of 22-day-old pups by using the optical dissector method. The experiments were performed in rats normally fed during gestation and lactation (G(+)L(+)), malnourished during gestation but rehabilitated during lactation (G(-)L(+)) and malnourished during gestation and lactation (G(-)L(-)). At day 1 of age, no significant differences in body and brain weights were observed between prenatally well-nourished and malnourished pups. Nevertheless, at this early age, pups born from mothers submitted to the 8% casein diet had significantly higher cortical net percent NA release than pups born from mothers receiving the 25% casein diet. At weaning (22 days of age) G(-)L(+) rats had, compared to the G(+)L(+) group, similar body weight, brain weight and [(3)H]-NA release values, but significantly higher neuron density scores in the lateral region of the occipital cortex. In contrast, at 22 days of age, G(-)L(-) rats exhibited, compared to G(+)L(+) animals, significant deficits in body and brain weights as well as significant increases in cortical net percent NA release together with enhanced packing density of neurons in the lateral, dorso-lateral and dorsal regions of the occipital cortex. Moreover, in G(-)L(-) animals was not found the laterodorsal histogenetic gradient of neuronal cell packing density observed in G(+)L(+)rats. Results suggest that mild prenatal malnutrition per se is able to induce deleterious effects on cortical neuronal density, in spite of nutritional rehabilitation during lactation, through a mechanism involving central NA hyperactivity during gestation. Prosecution of malnutrition after birth magnifies both neurochemical and morphometric disorders.

Analysis of Variance↗
PubMed1999

Cerebral tumor-like American trypanosomiasis in acquired immunodeficiency syndrome.

Cerebral tumor-like American trypanosomiasis (CTLAT) is an uncommon complication of Chagas' disease, observed only in immunosuppressed patients. We assessed 10 human immunodeficiency virus-positive patients with Chagas' disease who presented with CTLAT. All patients had neurological involvement and 6 developed intracranial hypertension. Neuroimaging studies showed supratentorial lesions in 9 patients, being single in 8. One case had infratentorial and supratentorial lesions. Low CD4+ cell counts were observed in all the cases and in 6 of them CTLAT was the first manifestation of acquired immunodeficiency syndrome. Serological tests for Chagas' disease were positive in 6 of 8 patients. Trypanosoma cruzi was identified in all brain specimens and in three cerebrospinal fluid samples. CTLAT should be considered in the differential diagnosis of intracranial mass lesions in human immunodeficiency virus-positive patients and should be added to the list of acquired immunodeficiency syndrome-defining illnesses.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Human immunodeficiency virus infection associated arthritis: clinical characteristics.

OBJECTIVE: To define the frequency and characteristics of human immunodeficiency virus (HIV) associated arthritis. METHODS: A total of 270 patients with HIV infection were prospectively evaluated for the presence of rheumatic complaints. Diagnosis of HIV infection was performed by ELISA and confirmed by Western blot, and all HIV patients were classified according to the US Centers for Disease Control criteria. RESULTS: Twenty-one (7.8%) patients presented with HIV associated arthritis. Other arthritides including HLA-B27 related, such as Reiter's syndrome, psoriatic arthritis, and rheumatoid arthritis, were excluded. Seventeen were men and 4 women, with a mean age of 34.8 years (SD 11.1). Fourteen (66%) were homosexuals, 4 (19%) intravenous drug users, and 3 (14%) heterosexuals. Twelve (57%) were in stage IV, 5 (23%) in stage III, and 4 (9%) in stage II. Ten (47%) patients had oligoarticular involvement, 8 (38%) monoarticular, 2 (9%) asymmetric polyarthritis, and one (4%) symmetric polyarthritis. Rheumatoid factor and HLA-B27 antigen were negative in all (15) patients studied. The mean duration of arthritis was 2 weeks (1-24). No differences in duration of arthritis were found among the different risk factors (p = 0.811), HIV stages (p = 0.205), and type of articular involvement (p = 0.252). There was, however, a trend between the number of involved joints and stages of HIV infection (p = 0.13). CONCLUSION: The pattern of joint involvement of HIV associated arthritis is similar to that of other viral disorders: acute onset, short duration, no recurrences, and no erosive changes.

Adolescent↗
PubMed1997

Disseminated histoplasmosis with orofacial involvement in HIV-I-infected patients with AIDS: manifestations and treatment.

INTRODUCTION: Histoplasmosis is a deep mycosis which is increasingly seen in HIV disease. It has emerged as a relatively common infection in Argentina, mainly in HIV-infected and other immunocompromised persons, and is often disseminated (DH). OBJECTIVE: The aim of this study was to describe 32 HIV-I-seropositive patients with AIDS who had DH, 21 of whom presented orofacial manifestations, and their treatment. SUBJECTS AND METHODS: A retrospective study of 876 HIV-seropositive patients revealed 32 with a clinical diagnosis of DH confirmed by special stains on histopathologic specimens, or by culture. RESULTS: Thirty-two HIV-infected patients had DH. Two-thirds (21 patients) had oral lesions of histoplasmosis, of which six presented with oral cavity (OC) lesions as the sole orofacial manifestation of disease, nine patients presented oral and facial (OF) lesions and six presented facial lesions only. A unique case of submandibular histoplasmosis is also reported. Antifungal therapy cleared more than 90% of the orofacial and disseminated lesions of histoplasmosis. Over the 7-year period there was a mortality of 85%. CONCLUSION: DH should be considered as a possible diagnosis in HIV patients with chronic ulcerative or nodular orofacial or oral lesions. Itraconazole is an effective and acceptable therapy.

AIDS-Related Opportunistic Infections↗
PubMed1996

Cross-tolerance to acute administration of mu and kappa opioid agonists at the spinal cord level in the rat.

Development of tolerance and cross-tolerance after acute administration of the mu agonist morphine and the kappa agonist U-50,488H was assessed in rats, through recording of a C-fiber-evoked spinal nociceptive reflex. Rats rendered tolerant to morphine (a single dose of 1 mg/kg i.p.) showed, after a 5-hour period, tolerance to morphine and cross-tolerance to the kappa-opioid receptor agonist U-50,488H, as revealed by depressed C-reflex responsiveness. In contrast, pretreatment with U-50,488H (a single dose of 1 mg/kg i.p.) rendered tolerant the rats to U-50,488H, but the animals did not develop cross-tolerance to morphine. Results indicate that acute administration of mu and kappa ligands leads to development of unidirectional cross-tolerance in rat spinal cord. This points to limitations in using alternated mu and kappa opioid agonists to bypass the problem of development of opioid tolerance in chronic pain complaints.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1995

Serologic evaluation of human immunodeficiency virus type 1-infected individuals from Argentina and the United States indicates a similar distribution of subgroup B isolates.

Utilizing peptides based on the V3 region of gp120, we undertook a serologic examination of human immunodeficiency virus type 1 (HIV-1)-infected individuals from Argentina to determine if prevalent HIV-1 isolates could be identified in this population. Our findings suggest that a similar pool of HIV-1 subgroup B isolates exists in both Argentina and the United States.

Amino Acid Sequence↗
PubMed1995

Central noradrenergic hyperactivity early in life: a hypothesis on the origin of morpho-functional brain disorders induced by malnutrition.

Many studies have revealed that malnutrition, caused either by insufficient or unbalanced diet, during early stages of growth and development could result in a variety of morpho-functional brain disturbances, whose severity depends on the time of onset, duration and intensity of the nutritional injury. Nevertheless, little is known about the intimate mechanisms by which early malnutrition impairs brain structure and function. This article reviews evidence showing that (i) developmental malnutrition induces central noradrenergic hyperactivity, (ii) noradrenaline exerts a trophic role during brain development, and (iii) pharmacological reduction of central noradrenergic hyperactivity prevents malnutrition-induced functional brain disturbances.

Animals↗
PubMed1992

Supraclavicular subclavian vein catheterization: modified landmarks for needle insertion.

STUDY OBJECTIVE: Identification of reliable landmarks for supraclavicular subclavian vein catheterization that requires no patient manipulation and is easily located. PATIENT POPULATION: Thirty-five fresh human cadavers. DESIGN AND METHODS: Descriptive study of percutaneous guide wire placement into the subclavian vein using as a new landmark the junction of middle and medial thirds of the clavicle. The position of the guide wire was confirmed by palpation of the wire in the subclavian vein during autopsy. RESULTS: Successful placement of a guide wire into the subclavian vein occurred in 33 of 35 cadavers (94%) using the new landmark. CONCLUSION: The new landmark for supraclavicular subclavian vein catheterization is reliable, requires no patient manipulation, and is as successful as the standard landmarks.

Adult↗
PubMed1992

An immunocytochemical test for the diagnosis of antibodies to Plasmodium vivax.

An immunocytochemical peroxidase test (ICPT) has been developed to allow serological measurement of the antibody response to Plasmodium vivax by light microscopy. Acetone fixed P. vivax erythrocyte stages were used as source of antigen. The immunofluorescent antibody test (IFAT) was used as reference test. In testing sera from individuals infected with P. vivax in southeastern Venezuela a high correlation (100%) was obtained between the ICPT and the IFAT. There were cross reactions with sera from patients with malaria by P. falciparum but not with those from patients with other parasitic diseases. Antibody titres as measured by the ICPT showed a positive correlation with past P. vivax malarial experiences.

Animals↗
PubMed1990

Aortoiliac occlusion secondary to atherosclerotic plaque rupture as the result of blunt trauma.

Abdominal aortic injuries secondary to blunt trauma are uncommon, particularly without associated visceral injury or external signs of localized trauma. Blunt trauma-induced abdominal aortic injuries most frequently result in intimal tearing. The most common mechanism is localized impact over the lower abdomen from sudden deceleration against a fixed object. We present the case of a patient with atheromatous plaque rupture in the distal abdominal aorta associated with acute aortoiliac occlusion as the result of a fall. Atherosclerotic disease may be present in young asymptomatic individuals and may be a predisposing factor for aortic intimal tearing. A high degree of suspicion and periodic reassessment of peripheral circulation in trauma patients are required to ensure early diagnosis of this injury.

Adult↗