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A Guevara

Publications and source records attributed to A Guevara.

At least 19 recordsLinked to original sources
PubMed2004

Cross-species transferability and mapping of genomic and cDNA SSRs in pines.

Two unigene datasets of Pinus taeda and Pinus pinaster were screened to detect di-, tri- and tetranucleotide repeated motifs using the SSRIT script. A total of 419 simple sequence repeats (SSRs) were identified, from which only 12.8% overlapped between the two sets. The position of the SSRs within their coding sequences were predicted using FrameD. Trinucleotides appeared to be the most abundant repeated motif (63 and 51% in P. taeda and P. pinaster, respectively) and tended to be found within translated regions (76% in both species), whereas dinucleotide repeats were preferentially found within the 5'- and 3'-untranslated regions (75 and 65%, respectively). Fifty-three primer pairs amplifying a single PCR fragment in the source species (mainly P. taeda), were tested for amplification in six other pine species. The amplification rate with other pine species was high and corresponded with the phylogenetic distance between species, varying from 64.6% in P. canariensis to 94.2% in P. radiata. Genomic SSRs were found to be less transferable; 58 of the 107 primer pairs (i.e. 54%) derived from P. radiata amplified a single fragment in P. pinaster. Nine cDNA-SSRs were located to their chromosomes in two P. pinaster linkage maps. The level of polymorphism of these cDNA-SSRs was compared to that of previously and newly developed genomic-SSRs. Overall, genomic SSRs tend to perform better in terms of heterozygosity and number of alleles. This study suggests that useful SSR markers can be developed from pine ESTs.

Base Sequence↗
PubMed2003

Circulating recombinant form CRF02_AG in South America.

With the objective of monitoring the distribution of HIV-1 subtypes and circulating recombinant forms (CRFs)in South America, population-based surveillance studies were performed in seven countries. Peripheral blood mononuclear cell, filter paper, fresh blood, and cocultivation samples were collected from HIV-positive patients from Colombia, Ecuador, Peru, Bolivia, Chile, Argentina, and Uruguay, during a 7-year period(1995-2001). DNA was prepared and HIV envelope subtypes were determined by heteroduplex mobility as-say and DNA sequencing from 1289 HIV-positive samples. While subtypes B and F were the most commonly observed subtypes, two CRF02_AG strains were detected, in Ecuador. This is the first report of the existence of this CRF in South America.

Adult↗
PubMed2001

Human infection with Ascaris lumbricoides is associated with suppression of the interleukin-2 response to recombinant cholera toxin B subunit following vaccination with the live oral cholera vaccine CVD 103-HgR.

To investigate the potential immunomodulatory effects of concurrent ascariasis on the cytokine response to a live oral vaccine, we measured cytokine responses to cholera toxin B subunit (CT-B) following vaccination with the live oral cholera vaccine CVD 103-HgR in Ascaris lumbricoides-infected subjects randomized in a double-blind study to receive two doses of either albendazole or placebo prior to vaccination and in a group of healthy U.S. controls. Postvaccination cytokine responses to CT-B were characterized by transient increases in the production of interleukin-2 (IL-2; P = 0.02) and gamma interferon (IFN-gamma; P = 0.001) in the three study groups combined; however, postvaccination increases in IFN-gamma were significant only in the albendazole-treated A. lumbricoides infection group (P = 0.008). Postvaccination levels of IL-2 were significantly greater in the albendazole-treated group compared with the placebo group (P = 0.03). No changes in levels of Th1 and Th2 cytokines in response to control ascaris antigens were observed over the same period. These findings indicate that vaccination with CVD 103-HgR is associated with a Th1 cytokine response (IL-2 and IFN-gamma) to CT-B, that infection with A. lumbricoides diminishes the magnitude of this response, and that albendazole treatment prior to vaccination was able to partially reverse the deficit in IL-2. The potential modulation of the immune response to oral vaccines by geohelminth parasites has important implications for the design of vaccination campaigns in geohelminth-endemic areas.

Adult↗
PubMed2000

Human infection with Ascaris lumbricoides is associated with a polarized cytokine response.

To define the cytokine response to Ascaris lumbricoides infection, the cellular immune response to adult and larval-stage Ascaris antigens in young adults with moderate infection intensities (n=73) was compared with that of a group of uninfected control subjects (n=40). A. lumbricoides-infected subjects had significantly greater lymphoproliferative responses to adult and larval-stage antigens, compared with uninfected control subjects (P<.01). The frequencies of parasite antigen-stimulated peripheral blood mononuclear cell (PBMC)-expressing interleukin (IL)-4 and IL-5 were significantly greater in the infected group (P<.001), whereas the frequencies of IL-10- and interferon-gamma-expressing PBMC were similar in the 2 groups studied. The ratios of Th2 to Th1 cytokine frequencies were significantly elevated in the infected group, compared with those in uninfected subjects, as was IL-5 protein production by PBMC stimulated with adult (P<.05) and L3/L4 stage (P<.001) antigens. Analysis of these data indicates that A. lumbricoides infections in endemic regions are associated with a highly polarized type 2 cytokine response.

Adolescent↗
PubMed2000

Albendazole treatment of children with ascariasis enhances the vibriocidal antibody response to the live attenuated oral cholera vaccine CVD 103-HgR.

Because concurrent infections with geohelminth parasites might impair the immune response to oral vaccines, we studied the vibriocidal antibody response to the oral cholera vaccine CVD 103-HgR in children infected with Ascaris lumbricoides and investigated the effect of albendazole pretreatment on the postvaccination response. Children with ascariasis were randomized to receive either 2 sequential doses of 400 mg of albendazole or placebo. After the second dose, CVD 103-HgR was given, and serum vibriocidal antibody levels were measured before and 10 days after vaccination. Postvaccination rates of seroconversion were greater in the treatment group that received albendazole (P=.06). Significantly greater rates of seroconversion and geometric mean titer were observed in the albendazole group in subjects with non-O ABO blood groups. A significant association was observed between vibriocidal seroconversion rates and treatment group, suggesting that A. lumbricoides infections impair the immune response to oral cholera vaccine, particularly in subjects of non-O blood groups.

Adolescent↗
PubMed1997

Pharmacokinetics and hepatotoxicity of diclofenac using an isolated perfused rat liver.

Pharmacokinetics and hepatotoxicity of diclofenac was studied in a recirculating model of isolated perfused rat liver. Ten male Sprague-Dawley rat (weighing 230-330 g) livers were perfused for 2 h with 250 mL Krebs-Henseleit bicarbonate buffer that contained 10.75 mg (group A, n = 5) and 1.075 mg (group B, n = 5) of diclofenac (approximately 100 and 10 times the therapeutic dose in man, respectively). Samples were collected from the efflux at regular time intervals for the determination of diclofenac concentrations by a high performance liquid chromatography (HPLC) method. Pharmacokinetic analyses were carried out using a computer program. To establish viability of the liver and toxicity of the drug, enzyme activity measurements of lactate dehydrogenase (LDH), aspartate aminotransferase (SGOT) and piruvate aminotransferase (SGPT) were performed by a spectrophotometric method. Oxygen consumption was also recorded during the entire perfusion period. Both groups presented bicompartmental kinetics. Concentration profiles showed that group B had a better metabolizing capacity, reflected in a 85.54 +/- 37.05 min half-life, a 0.52 +/- 0.19 mL min-1 g-1 liver clearance and a 0.517 +/- 0.188 extraction ratio, compared to group A, which presented a 123.95 +/- 88.13 min half-life, a 0.1164 +/- 0.067 mL min-1 g-1 liver clearance (P < 0.002) and a 0.116 +/- 0.680 extraction ratio (P < 0.002). LDH activity showed a significant increase in group A at 90 min in comparison with the control group, while in group B this increase was significantly higher at 10 min (P < 0.004). The aminotransferase levels did not show a significant increase. According to these results, diclofenac would not have a direct hepatotoxic effect, even at doses 100 times higher than therapeutic ones.

Alanine Transaminase↗
PubMed1997

Apolipoprotein B and E genetic polymorphisms in the Cayapa Indians of Ecuador.

Three DNA polymorphisms (XbaI, EcoRI, and Ins/Del) of the apolipoprotein B (APOB) gene and the CfoI polymorphism of the APOE gene were investigated in a sample of 96 Cayapa Indians from Ecuador. The frequencies of the X+ (0.182), R+ (1.000), and Del alleles (0.432) at the three APOB sites were found to be higher than and to differ significantly from those reported for East Asians. No comparisons could be made between the Cayapa and other native Americans because of the lack of data on these sites. We observed in our sample that, like native American populations but unlike East Asians, the APOE allele frequencies were characterized by the absence of the APOE*2 allele and by a high frequency of the APOE*4 allele (0.280). Besides a probable drift effect, the high APOE*4 value was tentatively attributed to an effect of selection. Because this allele enhances the absorption of cholesterol by the intestine, it could confer an advantage to carriers in an unfavorable environment (i.e., diet poor in cholesterol).

Adult↗
PubMed1996

Pharmacokinetics of vancomycin in patients with severely impaired renal function.

The pharmacokinetics of 1 g dose of intravenous vancomycin was studied in 8 patients with severe renal failure. Serum vancomycin levels were determined by fluorescence polarization immunoassay. After single dose of vancomycin peak concentrations ranged from 37.8 microg.ml-1 to 109.3 microg.ml-1 (mean 64.9 +/- 21.7 microg.ml-1). Vancomycin trough concentration 168h after administration of the antibiotic ranged from 2.23 microg.ml-1 to 11.42 microg.ml-1 (mean 6.55 +/- 2.8 microg.ml-1). The data were analyzed using a PCNONLINE computer program, and in all patients a triexponential model described how concentrations decreased in time. Three-compartment parameters obtained from the 8 patients were t1/2 alpha = 0.312 +/- 0.242 h, t1/2 beta 6.012 +/- 5.36 h, and t1/2 gamma = 131.0 +/- 46.7 h. Vd = 0.158 +/- 0.121 1.kg-1, Vdss = 0.920 +/- 0.248 1.kg-1 and total Cl = 0.10 +/- 0.049 1.h-1 per kg of weight. Between 1.5% and 21.2% of the administered vancomycin dose was eliminated during hemodialysis. The dialysis clearance of vancomycin ranged from 50.6 ml.min-1 to 76.8 ml.min-1 (average: 62.4 +/- 10.4 ml.min-1. However, after dialysis plasma concentrations returned to pre-dialysis values. In accordance to our kinetic study 1 g of vancomycin given every 7 days is adequate treatment for methicillin-resistant Staphylococcus aureus infections in patients with severe renal failure whose creatinine clearance is lower than 10 ml.min-1.

Adult↗
PubMed1995

Adverse drug reactions (ADRs) in patients with previous history of chronic alcohol consumption without signs of chronic hepatic damage. A prospective study.

An intensive and prospective drug surveillance method was used to monitor 105 hospitalized patients having a previous history of chronic alcohol consumption without signs of hepatic damage at the Dr. Sotero del Rio hospital, Santiago, Chile. The aim of the work was to characterize and study the incidence of ADRs associated with chronic alcohol addiction in patients hospitalized for different pathological conditions. The incidence of ADRs in this group (41.9%) was slightly higher than those from other studies carried out in our country in patients hospitalized in the internal medicine service from other Chilean hospitals. However, alcohol addiction was not considered in these studies. According to causality, 58.8% of the ADRs were regarded as probable, 6.9% as definite and 34.3% as possible. The severity of ADRs was determined as 18.6% mild, 53.9% moderate and 27.5% as severe events. These ADRs were manifested in a dose-related fashion (80.4%). Furosemide, heparin, and gentamicin were the drugs mainly associated with ADRs. The most commonly affected system were metabolic (33.3%), renal (19.6%), and gastrointestinal (19.6%). There was a higher incidence of ADRs in those patients with longer stay at the hospital, in patients on multiple-drug therapy, and in patients with impaired renal function. The frequency of ADRs was not related to age, sex, and pattern of alcohol consumption.

Adult↗
PubMed1994

Disposition of nifurtimox and metabolite activity against Trypanosoma cruzi using rat isolated perfused liver.

Nifurtimox disposition was investigated using the rat isolated perfused-liver method after administration of 25 micrograms mL-1 nifurtimox, and its disappearance was monitored by analysing the perfusate sample at various times. Biliary excretion was also measured. The drug concentration profile underwent a biexponential decline over the 2-h study period, with a terminal half-life of 62.76 +/- 17.56 min. Nifurtimox is a high clearance compound (15.23 +/- 5.53 mL min-1). The extraction ratio was 0.621 +/- 0.159. Biliary excretion accounted for 0.05% of the dose, the remainder consisting of highly polar metabolites. By 2 h, a minimal fraction of unchanged nifurtimox was recovered from the perfusate. Nifurtimox activity against Trypanosoma cruzi (clone CA-1) during the perfusion was also determined. Epimastigotes isolated from continuous culture were exposed to the samples of perfusate at different perfusion times in a microtitre plate. After an incubation time of 72 h at 27 degrees C, the parasite number in each well was counted under a microscope. From 0 to 75 min after the perfusion, the anti-trypanosomal activity decreased, but an increase in activity was observed at the later times. These findings show that active metabolites are formed during the perfusion.

Animals↗
PubMed1994

Distribution of hydatidosis and cysticercosis in different Peruvian populations as demonstrated by an enzyme-linked immunoelectrotransfer blot (EITB) assay. The Cysticercosis Working Group in Peru (CWG).

A serosurvey for human hydatidosis and cysticercosis was performed in different regions of Peru. Those regions included a known endemic area for cystic hydatid disease, a cooperative in the central Peruvian Andes near the city of Tarma, Department of Junin; three areas endemic for cysticercosis in the Departments of Ancash, Cuzco, and San Martin, where the status of hydatid disease is not well defined; and an urban shantytown near Lima, where neither zoonosis is known to be present. A seroprevalence for hydatidosis 1.9% (6 of 309) was found with both the enzyme-linked immunoelectrotransfer blot (EITB) and double diffusion assays in the area endemic for hydatidosis. Seroprevalence in the other zones tested was zero using only the EITB assay. Cysticercosis seroprevalence was high in pig-raising zones but low in the high-altitude, sheep-raising areas and in the seaport of Callao. No cross-reactions between Echinococcus granulosus and cysticercosis were noted in any of the regions studied. Hydatid infection remains a major health problem in the central Peruvian Andes where sheep raising is widely practiced; however, in those regions where mainly swine are raised, human hydatid infection is not a problem.

Abattoirs↗
PubMed1993

The disposition of nifurtimox in the rat isolated perfused liver: effect of dose size.

The disposition of nifurtimox was studied in the rat isolated perfused liver using a recirculating system. The drug was administered as a bolus (5.0, 15.0 or 30.0 micrograms mL-1), and its disappearance was monitored by analysing perfusate samples. In all experiments perfusate disappearance was monoexponential, and no significant difference was found between the three doses for the elimination constant (0.016, 0.011 and 0.012 min-1, respectively), half-life (46.6, 65.8 and 66.8 min, respectively), extraction rate (0.128, 0.091 and 0.099, respectively) and distribution volume (41.1, 47.3 and 30.7 mL g-1, respectively). At 30 micrograms mL-1 the hepatic clearance was lower than the other concentrations of nifurtimox (0.66, 0.51 and 0.34 mL min-1 g-1, respectively). Relatively little parent drug was recovered from the liver at the end of the perfusions. In summary, nifurtimox is cleared slowly from the rat isolated perfused liver, is poorly extracted by hepatocyte cells and is completely metabolized from 2 to 4 h after perfusion.

Animals↗
PubMed1993

Heparin-induced transaminase elevations: a prospective study.

An intensive and prospective surveillance study of 54 patients hospitalized in the Internal Medicine Unit of Clinical Hospital of the Catholic University of Chile, who required heparin in the period between June and December of 1991 was done. The aim of the work was to characterize and study the incidence of the adverse reactions associated with heparin therapy, with special emphasis on abnormal serum transaminase elevation. Abnormal transaminase elevation was defined as a rise over 20% of the serum transaminase baseline value. For determining the serum transaminase level, a UV spectrophotometric method was used. The incidence of the adverse drug reactions (ADR) was 24.1% (13 ADR), 8 of which (14.8%) were related with heparin therapy. Three of them (5.5%) corresponded to alanine transaminase (ALAT) increase and five (9.3%) to aspartate transaminase (ASAT) elevation. By means of global introspection method, 3 cases of ALAT increases were defined as probable and 6 as possible, while 5 ASAT increases were estimated as probable and 14 as possible. All of them were of slow onset, did not require treatment and hospital stay was not prolonged. Two patients' characteristics--age and sex--were associated with the development of heparin-induced abnormal alanine transaminase concentrations. The younger male patients showed a greater frequency of heparin-induced ALAT elevation. However, this association was not observed with the heparin-induced ASAT increase. These reactions were dose-dependent. Patients with heparin-induced ALAT elevation received a dose of 154,220 IU +/- 72,970 IU in comparison to patients without that adverse reaction who received 96,210 IU +/- 40,340 IU. This difference was statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Enzyme-linked immunoelectrotransfer blot test for diagnosis of human hydatid disease.

Sera from 71 patients with surgically confirmed hydatid disease (which is caused by Echinococcus granulosus) were studied by an enzyme-linked immunoelectrotransfer blot (EITB) assay. Sera from patients either with other cestode infections or with another illness were used as controls. Results of the EITB test for hydatidosis were compared with those of the double-diffusion (DD5) test and an enzyme-linked immunosorbent assay (ELISA). In the EITB assay with bovine lyophilized hydatid fluid, three antigen bands of 8, 16, and 21 kDa were diagnostically important. The sensitivity of the assay by using these antigen bands was 80% for hepatic cysts, 56% for pulmonary cysts, and 56% for cysts located in multiple organs. In sera from controls, the specificity of the EITB assay was 100%. Cross-reactions to the 8-, 16-, and 21-kDa bands occurred, respectively, in 12, 4, and 4% of sera from patients with cysticercosis. No cross-reactions were noted in patients infected with Hymenolepis nana. The ELISA in which swine hydatid fluid was used as the antigen was as sensitive as the EITB test but was less specific (80%) and frequently cross-reacted with sera from patients with other cestode infections. The sensitivity of the DD5 test, which uses sheep hydatid fluid, was low (47%) , but its specificity was as high as that of the EITB assay. However, in patients with cysticercosis, cross-reactions were observed in 23% of sera tested. Despite the higher sensitivity found with the EITB assay, 23% (n = 5) of the serum samples that were positive by the DD5 test were not detected by the EITB assay. The EITB assay offers greater sensitivity and specificity than do the ELISA and the DD5 test. The highest proportion of hydatid cases is detected when the EITB and DD5 tests are run simultaneously.

Antigens, Helminth↗
PubMed1991

Effect of treatment on serum antibody to Hymenolepis nana detected by enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) was developed to measure serum immunoglobulin G antibodies in 65 patients infected with Hymenolepis nana and 30 noninfected patients. Antibody was detected in 51 of 65 (sensitivity, 79%) and 5 of 30 H. nana-negative patients (specificity, 83%). Nine patients infected with H. nana were treated with praziquantel (20 to 25 mg/kg of body weight). Antibody disappeared from the sera at 90 days in six patients, five of whom had eliminated H. nana. Antibody persisted in three patients in whom H. nana infection did not clear after treatment. The H. nana ELISA had a high rate of cross-reactions with sera from patients with cysticercosis (8 of 29 [28%]) and hydatidosis (8 of 23 [35%]). The ELISA for H. nana may be useful for defining the epidemiology of H. nana infections, especially in areas free from cysticercosis and hydatidosis.

Adolescent↗
PubMed1991

Abdominal sparganosis in Ecuador: a case report.

Sparganosis, infection with plerocercoids of the pseudophyllidean tapeworm Spirometra, rarely has been described in Ecuador. We report the details of a human case of sparganosis identified serendipitously in the course of an abdominal hernia repair. The parasite was found moving freely upon the external oblique fascia adjacent to the site of a direct abdominal hernia. The organism was recovered intact, photographed while alive and preserved for subsequent detailed morphological studies. The presumed route of entry into this patient was percutaneous, after application of a poultice of snake flesh to the site of a painful abdominal hernia. The literature on sparganosis in South America is reviewed. This is the second case of human sparganosis reported from Ecuador.

Abdominal Muscles↗
PubMed1991

Concentrations of amocarzine in plasma of 71 Ecuadorian patients of two different races receiving 3 mg/kg b.i.d. and 5 mg/kg o.d. oral postprandial doses for 3 days.

The possible influence of sex, race and of postprandial administration conditions (either immediately after the end of meal or one hour later) on the plasma concentrations of amocarzine and its N-oxide metabolite, CGP 13 231, was investigated. 71 Ecuadorian patients (48 males and 23 females) of two different races (Indio and Negro) infected with Onchocerca volvulus participated in the study. The concentrations were measured on day 3 at times 3 and 6 h after postprandial administration in the morning of a treatment with either a dose of 5 mg/kg of amocarzine once daily (12 patients) or 3 mg/kg twice daily (59 patients) for 3 days. The concentrations of unchanged drug and of CGP 13 231 measured after the 5 mg/kg treatment were in the low range of those expected from dose proportionality by the comparison with the 3 mg/kg. After the 3 mg/kg dose, no significant difference in concentration of both compounds were detected between the male and female patients between Indio and Negro patients, between the administration immediately after food intake and one hour later. The only detected difference (P = 0.05) was that between Indio and Negro patients for the concentrations of CGP 13 231 at time 3 h. This difference was not confirmed at time 6 h. Therefore, the administration of amocarzine either immediately or one hour after food intake appeared to produce reproducible absorption conditions which were not influenced by sex and race.

Absorption↗