JOSE LUIS RAMIREZ - Academia.edu (original) (raw)

Papers by JOSE LUIS RAMIREZ

Sensors and Actuators B-chemical, 2008

In this paper a novel sensor operating strategy is introduced. This consists of a discontinuous m... more In this paper a novel sensor operating strategy is introduced. This consists of a discontinuous mode of operating temperature-modulated sensors. The objective is to reduce power consumption while keeping sensor performance high in view of monitoring the conservation stage of apples along the logistics chain. In this approach, the system will consist of a radio frequency identification reader with onboard gas sensors and a flexible tag with temperature and humidity sensors. The gas sensitive part is integrated by an array of Pt-doped and Pd-doped tin and tungsten oxides deposited by drop coating onto silicon micro-machined substrates. By operating sensors at an optimised temperature-modulation mode and by powering them during the measurement phase only, the system shows good potential to integrate a gas monitor for the application envisaged. Excellent results have been obtained, not only in the accurate identification (i.e., 100% success rate) of the gases that are relevant for monitoring apple quality during transport or storage, but also in quantifying the concentration of the species analysed. Additionally, it was shown that measurement time could be dramatically reduced down to 9.5 s if only identification was attempted or down to 39 s if quantification was envisaged. This allows for reducing power consumption without compromising system performance.

European Journal of Biochemistry, 2002

The characterization of the gene encoding Leishmania donovani phosphofructokinase (PFK) and the b... more The characterization of the gene encoding Leishmania donovani phosphofructokinase (PFK) and the biochemical properties of the expressed enzyme are reported. L. donovani has a single PFK gene copy per haploid genome that encodes a polypeptide with a deduced molecular mass of 53 988 and a pI of 9.26. The predicted amino acid sequence contains a C-terminal tripeptide that conforms to an established signal for glycosome targeting. L. donovani PFK showed most sequence similarity to inorganic pyrophosphate (PPi)-dependent PFKs, despite being ATP-dependent. It thereby resembles PFKs from other Kinetoplastida such as Trypanosoma brucei, Trypanoplasma borreli (characterized in this study), and a PFK found in Entamoeba histolytica. It exhibited hyperbolic kinetics with respect to ATP whereas the binding of the other substrate, fructose 6-phosphate, showed slight positive cooperativity. PPi, even at high concentrations, did not have any effect. AMP acted as an activator of PFK, shifting its kinetics for fructose 6-phosphate from slightly sigmoid to hyperbolic, and increasing considerably the affinity for this substrate, whereas GDP did not have any effect. Modelling studies and site-directed mutagenesis were employed to shed light on the structural basis for the AMP effector specificity and on ATP/PPi specificity among PFKs.

Memorias Do Instituto Oswaldo Cruz, 1997

Here we review the phenomenon of persistency in Leishmania (Viannia) braziliensis infections. In ... more Here we review the phenomenon of persistency in Leishmania (Viannia) braziliensis infections. In other Leishmania species where appropriate animal models exist, considerable advances in the understanding of basic immunologic mechanisms of persistency have been made; for a review see Aebisher (1994). On the contrary, the evidences of persistence in infections with L. braziliensis rest on studies of human clinical cases many of which we summarized and discussed in this work.

The Lancet Oncology

We aimed to assess the safety and effi cacy of erlotinib compared with standard chemo therapy for... more We aimed to assess the safety and effi cacy of erlotinib compared with standard chemo therapy for fi rst-line treatment of European patients with advanced EGFR-mutation positive NSCLC.

Journal of Medical Entomology, 2001

Cancer Chemotherapy and Pharmacology, 2008

Purpose A multicenter phase I trial to establish the recommended dose of CPT-11/docetaxel plus ci... more Purpose A multicenter phase I trial to establish the recommended dose of CPT-11/docetaxel plus cisplatin in advanced esophagogastric cancer patients and to correlate the efficacy and toxicity with genetic polymorphisms in DNA repair genes (XPD and XRCC3) and the UGT1A1 gene. Methods Four dose levels with a fixed dose of cisplatin (60 mg/m2), day 1, and dose-escalation of CPT-11 (50–70 mg/m2) and docetaxel (25–30 mg/m2), days 1 and 8, every 3 weeks were planned. Polymorphisms of XPD (Asp312Asn and Lys751Gln), XRCC3 (Thr241Met) and UGT1A1*28 were examined in baseline peripheral blood. Results Twenty-eight patients were included at three different dose levels. Dose-limiting toxicities were febrile neutropenia and diarrhea; the recommended dose was established at CPT-11 60 mg/m2 and docetaxel 25 mg/m2 plus cisplatin 60 mg/m2. Objective response was observed in 13 patients (50%). Median time to progression was 6.6 months, and median survival was 11.3 months. Median time to progression was 9.7 months for patients harboring the XRCC3 Met241Met genotype versus 8.4 months for patients with Thr241Met and 3.1 months for those with Thr241Thr (P = .04). Conclusions CPT-11/docetaxel plus cisplatin is active in patients with advanced esophagogastric cancer. XRCC3 Met241Thr polymorphisms could be a useful marker to predict prognosis in patients treated with a cisplatin-based chemotherapy. However, these results are required to be confirmed with a great number of patients.

European Journal of Biochemistry, 2002

The characterization of the gene encoding Leishmania donovani phosphofructokinase (PFK) and the b... more The characterization of the gene encoding Leishmania donovani phosphofructokinase (PFK) and the biochemical properties of the expressed enzyme are reported. L. donovani has a single PFK gene copy per haploid genome that encodes a polypeptide with a deduced molecular mass of 53 988 and a pI of 9.26. The predicted amino acid sequence contains a C-terminal tripeptide that conforms to an established signal for glycosome targeting. L. donovani PFK showed most sequence similarity to inorganic pyrophosphate (PPi)-dependent PFKs, despite being ATP-dependent. It thereby resembles PFKs from other Kinetoplastida such as Trypanosoma brucei, Trypanoplasma borreli (characterized in this study), and a PFK found in Entamoeba histolytica. It exhibited hyperbolic kinetics with respect to ATP whereas the binding of the other substrate, fructose 6-phosphate, showed slight positive cooperativity. PPi, even at high concentrations, did not have any effect. AMP acted as an activator of PFK, shifting its kinetics for fructose 6-phosphate from slightly sigmoid to hyperbolic, and increasing considerably the affinity for this substrate, whereas GDP did not have any effect. Modelling studies and site-directed mutagenesis were employed to shed light on the structural basis for the AMP effector specificity and on ATP/PPi specificity among PFKs.

Plant Molecular Biology Reporter, 1995

Somaclonal variants resistant to sugarcane mosaic virus (SCMV) were obtained from susceptible sug... more Somaclonal variants resistant to sugarcane mosaic virus (SCMV) were obtained from susceptible sugarcane cv PR62258 through somatic embryogenesis by increasing the number of subcultures of the embryogenic callus tissue in MS medium with 3 mg/L 2,4-dichlorophenoxyacetic acid. Transfers were made at 30-day intervals for 1, 2 or 3 subcultures. Two somaclones, namely AT626 and BT627, were selected by their resistance to SCMV. These subclones have maintained the resistance trait over seven years of testing in the field. In this report we identified the somaclonal SCMV resistant variants from the maternal line and the nonresistant somaclones, using the RAPD technique.

Human Genetics, 1993

A study on the presence of human papillomavirus (HPV) DNA sequences and focal epithelial hyperpla... more A study on the presence of human papillomavirus (HPV) DNA sequences and focal epithelial hyperplasia (FEH) in a family of Venezuelan ancestry has revealed that FEH is an HPV-induced disease presenting familial aggregation. The genealogical evidence indicates a genetic predisposition to the disease.

Applied Microbiology and Biotechnology, 1993

We have developed a rapid and sensitive assay for the detection of clostridial cells or spores in... more We have developed a rapid and sensitive assay for the detection of clostridial cells or spores in liquid food samples. The method recognizes Clostridium 16S (small ribosomal subunit RNA) rDNA (ribosomal DNA) sequences by a polymerase chain reaction-digoxigenin-labelling protocol, coupled to a capture oligonucleotide immobilized on a microtitre plate. The positive results are revealed by means of a colour reaction. In 6 h of non-intensive labour, we can detect as few as two to five clostridial cells or spores in experimentally contaminated soft drinks.

Sex-Steroid Interactions with Growth Hormone, 1999

Virchows Archiv, 1992

An in situ hybridization assay with digoxigenin-labelled probes was used to detect the presence o... more An in situ hybridization assay with digoxigenin-labelled probes was used to detect the presence of human papillomavirus (HPV) sequences in ten related Venezuelan patients with the diagnosis of focal epithelial hyperplasia. The samples displayed HPV sequences in all cases. Further restriction analysis in four of the patients suggested the presence of HPV-13 in oral lesions.

Actes du 1er Colloque (Trèves, 10-13 décembre 1987), 1990

The Journal of Protozoology, 1982

The DNA content of the hemoflagellate Leishmania brasiliensis, strain Y, has been determined by c... more The DNA content of the hemoflagellate Leishmania brasiliensis, strain Y, has been determined by colorimetric reactions and found to be nearly 0.226 pg/cell. When this DNA is bound to filters and hybridized with labeled rRNA from the same organism, saturation is reached at 0.47% of the DNA, corresponding to an estimated 160 ribosomal gene copies. When the DNA is sheared and centrifuged to equilibrium in CsCl gradients, two major satellites of the main band (rho = 1.712 g/cm3) are observed: a heavy one (1.720 g/cm3), which hybridizes with labeled rRNA, and a light one (1.699 g/cm3) with the electron microscopic characteristics of the kinetoplast DNA network.

Corrosion Reviews, 1996

... Frankel, Gerald S. / Gileadi, Eliezer / Han, En-Hou / Hassel, Achim W. / Kelly, Robert G. / K... more ... Frankel, Gerald S. / Gileadi, Eliezer / Han, En-Hou / Hassel, Achim W. / Kelly, Robert G. / Kim, Kyoo Young / Lunarska, Ellina / Marcus, Philippe / Maruyama, Toshio / Mudali, U. Kamachi / Newman, Roger / Olive, Jean-Marc / Rebak, Raul B. / Revie, R. Winston / Schmuki, Patrik ...

Memorias Do Instituto Oswaldo Cruz, 2002

Here we have characterized Leishmania major (Friedlin) telomeric terminus (the very end) using re... more Here we have characterized Leishmania major (Friedlin) telomeric terminus (the very end) using recombinants obtained by a vector-adaptor cloning protocol. As in L. donovani, the last nine nucleotides of L. major terminus are 5'-GGTTAGGGT-OH 3', differing from Trypanosoma cruzi and T. brucei terminus 5'GGGTTAGGG-OH 3', thus indicating that these sequences are genus specific. We have also made a comparative analysis between L. major and L. donovani telomere-associated sequences, and described a novel non-repeated telomeric associated sequence common to L. major low molecular weight chromosomal bands.

Inapparent infections of Trypanosoma cruzi were detected in symptomless seropositive people livin... more Inapparent infections of Trypanosoma cruzi were detected in symptomless seropositive people living in close proximity, and under the same conditions of risk, to patients with acute Chagas disease. Similar infections were also detected in sera samples of people from 25 villages of western Venezuela where Chagas disease is endemic. Seropositivity in all the 1,251 studied samples was established by use of 3 serological methods (direct agglutination test, indirect immunofluorescence antibody test, and enzyme-linked immunosorbent assay). Each seropositive sample was tested for detection of anti-T. cruzi-specific immunoglobulin (Ig) M and IgG levels and specific T. cruzi infection by molecular methodology (polymerase chain reaction assay). The combined analysis of the serologic (IgM and IgG levels), molecular (specific T. cruzi DNA), and statistical findings demonstrated the existence of a different stage of T. cruzi infection in asymptomatic patients, which is suggested to be recognized as inapparent infection. Its definition, significance, and comparison with typical Chagas disease phases are presented, and its potential epidemiological importance is discussed.

A clinical, parasitologic, and serologic study carried out between 1988 and 1996 on 59 acute-phas... more A clinical, parasitologic, and serologic study carried out between 1988 and 1996 on 59 acute-phase patients in areas of western Venezuela where Chagas' disease is endemic showed 19 symptomatic patterns or groups of symptoms appearing in combination with different frequencies. The symptomatic pattern with the highest frequency was that showing simultaneously fever, myalgia, headache, and Romaña's sign, which was detected in 20% of the acute-phase patients. Asymptomatic individuals and patients with fever as the only sign of the disease made up 15% and 11.9% of the total acute cases, respectively. Statistical correlation analysis revealed that xenodiagnosis and hemoculture were the most reliable and concordant of the five parasitologic methods used; these two methods also showed the highest proportions in detecting any clinical symptomatic pattern in acute-phase patients. A similar high reliability and concordance was obtained with a direct agglutination test, an indirect immunofluorescent antibody test, and an ELISA as serologic tests, which also showed a higher proportion of positive detection of clinical patterns than parasitologic methods (P Ͻ 0.001). It is recommended that individuals coming from endemic areas showing mild and/or severe clinical manifestations should be suspected of being in contact or having been in contact with Trypanosoma cruzi, be referred for parasitologic and serologic evaluations to confirm the presumptive clinical diagnosis of acute Chagas' disease, and start specific treatment. The epidemiologic implications of the present findings are discussed and the use of similar methodology to evaluate other areas where Chagas' disease is endemic is suggested.

Sensors and Actuators B-chemical, 2008

In this paper a novel sensor operating strategy is introduced. This consists of a discontinuous m... more In this paper a novel sensor operating strategy is introduced. This consists of a discontinuous mode of operating temperature-modulated sensors. The objective is to reduce power consumption while keeping sensor performance high in view of monitoring the conservation stage of apples along the logistics chain. In this approach, the system will consist of a radio frequency identification reader with onboard gas sensors and a flexible tag with temperature and humidity sensors. The gas sensitive part is integrated by an array of Pt-doped and Pd-doped tin and tungsten oxides deposited by drop coating onto silicon micro-machined substrates. By operating sensors at an optimised temperature-modulation mode and by powering them during the measurement phase only, the system shows good potential to integrate a gas monitor for the application envisaged. Excellent results have been obtained, not only in the accurate identification (i.e., 100% success rate) of the gases that are relevant for monitoring apple quality during transport or storage, but also in quantifying the concentration of the species analysed. Additionally, it was shown that measurement time could be dramatically reduced down to 9.5 s if only identification was attempted or down to 39 s if quantification was envisaged. This allows for reducing power consumption without compromising system performance.

European Journal of Biochemistry, 2002

The characterization of the gene encoding Leishmania donovani phosphofructokinase (PFK) and the b... more The characterization of the gene encoding Leishmania donovani phosphofructokinase (PFK) and the biochemical properties of the expressed enzyme are reported. L. donovani has a single PFK gene copy per haploid genome that encodes a polypeptide with a deduced molecular mass of 53 988 and a pI of 9.26. The predicted amino acid sequence contains a C-terminal tripeptide that conforms to an established signal for glycosome targeting. L. donovani PFK showed most sequence similarity to inorganic pyrophosphate (PPi)-dependent PFKs, despite being ATP-dependent. It thereby resembles PFKs from other Kinetoplastida such as Trypanosoma brucei, Trypanoplasma borreli (characterized in this study), and a PFK found in Entamoeba histolytica. It exhibited hyperbolic kinetics with respect to ATP whereas the binding of the other substrate, fructose 6-phosphate, showed slight positive cooperativity. PPi, even at high concentrations, did not have any effect. AMP acted as an activator of PFK, shifting its kinetics for fructose 6-phosphate from slightly sigmoid to hyperbolic, and increasing considerably the affinity for this substrate, whereas GDP did not have any effect. Modelling studies and site-directed mutagenesis were employed to shed light on the structural basis for the AMP effector specificity and on ATP/PPi specificity among PFKs.

Memorias Do Instituto Oswaldo Cruz, 1997

Here we review the phenomenon of persistency in Leishmania (Viannia) braziliensis infections. In ... more Here we review the phenomenon of persistency in Leishmania (Viannia) braziliensis infections. In other Leishmania species where appropriate animal models exist, considerable advances in the understanding of basic immunologic mechanisms of persistency have been made; for a review see Aebisher (1994). On the contrary, the evidences of persistence in infections with L. braziliensis rest on studies of human clinical cases many of which we summarized and discussed in this work.

The Lancet Oncology

We aimed to assess the safety and effi cacy of erlotinib compared with standard chemo therapy for... more We aimed to assess the safety and effi cacy of erlotinib compared with standard chemo therapy for fi rst-line treatment of European patients with advanced EGFR-mutation positive NSCLC.

Journal of Medical Entomology, 2001

Cancer Chemotherapy and Pharmacology, 2008

Purpose A multicenter phase I trial to establish the recommended dose of CPT-11/docetaxel plus ci... more Purpose A multicenter phase I trial to establish the recommended dose of CPT-11/docetaxel plus cisplatin in advanced esophagogastric cancer patients and to correlate the efficacy and toxicity with genetic polymorphisms in DNA repair genes (XPD and XRCC3) and the UGT1A1 gene. Methods Four dose levels with a fixed dose of cisplatin (60 mg/m2), day 1, and dose-escalation of CPT-11 (50–70 mg/m2) and docetaxel (25–30 mg/m2), days 1 and 8, every 3 weeks were planned. Polymorphisms of XPD (Asp312Asn and Lys751Gln), XRCC3 (Thr241Met) and UGT1A1*28 were examined in baseline peripheral blood. Results Twenty-eight patients were included at three different dose levels. Dose-limiting toxicities were febrile neutropenia and diarrhea; the recommended dose was established at CPT-11 60 mg/m2 and docetaxel 25 mg/m2 plus cisplatin 60 mg/m2. Objective response was observed in 13 patients (50%). Median time to progression was 6.6 months, and median survival was 11.3 months. Median time to progression was 9.7 months for patients harboring the XRCC3 Met241Met genotype versus 8.4 months for patients with Thr241Met and 3.1 months for those with Thr241Thr (P = .04). Conclusions CPT-11/docetaxel plus cisplatin is active in patients with advanced esophagogastric cancer. XRCC3 Met241Thr polymorphisms could be a useful marker to predict prognosis in patients treated with a cisplatin-based chemotherapy. However, these results are required to be confirmed with a great number of patients.

European Journal of Biochemistry, 2002

The characterization of the gene encoding Leishmania donovani phosphofructokinase (PFK) and the b... more The characterization of the gene encoding Leishmania donovani phosphofructokinase (PFK) and the biochemical properties of the expressed enzyme are reported. L. donovani has a single PFK gene copy per haploid genome that encodes a polypeptide with a deduced molecular mass of 53 988 and a pI of 9.26. The predicted amino acid sequence contains a C-terminal tripeptide that conforms to an established signal for glycosome targeting. L. donovani PFK showed most sequence similarity to inorganic pyrophosphate (PPi)-dependent PFKs, despite being ATP-dependent. It thereby resembles PFKs from other Kinetoplastida such as Trypanosoma brucei, Trypanoplasma borreli (characterized in this study), and a PFK found in Entamoeba histolytica. It exhibited hyperbolic kinetics with respect to ATP whereas the binding of the other substrate, fructose 6-phosphate, showed slight positive cooperativity. PPi, even at high concentrations, did not have any effect. AMP acted as an activator of PFK, shifting its kinetics for fructose 6-phosphate from slightly sigmoid to hyperbolic, and increasing considerably the affinity for this substrate, whereas GDP did not have any effect. Modelling studies and site-directed mutagenesis were employed to shed light on the structural basis for the AMP effector specificity and on ATP/PPi specificity among PFKs.

Plant Molecular Biology Reporter, 1995

Somaclonal variants resistant to sugarcane mosaic virus (SCMV) were obtained from susceptible sug... more Somaclonal variants resistant to sugarcane mosaic virus (SCMV) were obtained from susceptible sugarcane cv PR62258 through somatic embryogenesis by increasing the number of subcultures of the embryogenic callus tissue in MS medium with 3 mg/L 2,4-dichlorophenoxyacetic acid. Transfers were made at 30-day intervals for 1, 2 or 3 subcultures. Two somaclones, namely AT626 and BT627, were selected by their resistance to SCMV. These subclones have maintained the resistance trait over seven years of testing in the field. In this report we identified the somaclonal SCMV resistant variants from the maternal line and the nonresistant somaclones, using the RAPD technique.

Human Genetics, 1993

A study on the presence of human papillomavirus (HPV) DNA sequences and focal epithelial hyperpla... more A study on the presence of human papillomavirus (HPV) DNA sequences and focal epithelial hyperplasia (FEH) in a family of Venezuelan ancestry has revealed that FEH is an HPV-induced disease presenting familial aggregation. The genealogical evidence indicates a genetic predisposition to the disease.

Applied Microbiology and Biotechnology, 1993

We have developed a rapid and sensitive assay for the detection of clostridial cells or spores in... more We have developed a rapid and sensitive assay for the detection of clostridial cells or spores in liquid food samples. The method recognizes Clostridium 16S (small ribosomal subunit RNA) rDNA (ribosomal DNA) sequences by a polymerase chain reaction-digoxigenin-labelling protocol, coupled to a capture oligonucleotide immobilized on a microtitre plate. The positive results are revealed by means of a colour reaction. In 6 h of non-intensive labour, we can detect as few as two to five clostridial cells or spores in experimentally contaminated soft drinks.

Sex-Steroid Interactions with Growth Hormone, 1999

Virchows Archiv, 1992

An in situ hybridization assay with digoxigenin-labelled probes was used to detect the presence o... more An in situ hybridization assay with digoxigenin-labelled probes was used to detect the presence of human papillomavirus (HPV) sequences in ten related Venezuelan patients with the diagnosis of focal epithelial hyperplasia. The samples displayed HPV sequences in all cases. Further restriction analysis in four of the patients suggested the presence of HPV-13 in oral lesions.

Actes du 1er Colloque (Trèves, 10-13 décembre 1987), 1990

The Journal of Protozoology, 1982

The DNA content of the hemoflagellate Leishmania brasiliensis, strain Y, has been determined by c... more The DNA content of the hemoflagellate Leishmania brasiliensis, strain Y, has been determined by colorimetric reactions and found to be nearly 0.226 pg/cell. When this DNA is bound to filters and hybridized with labeled rRNA from the same organism, saturation is reached at 0.47% of the DNA, corresponding to an estimated 160 ribosomal gene copies. When the DNA is sheared and centrifuged to equilibrium in CsCl gradients, two major satellites of the main band (rho = 1.712 g/cm3) are observed: a heavy one (1.720 g/cm3), which hybridizes with labeled rRNA, and a light one (1.699 g/cm3) with the electron microscopic characteristics of the kinetoplast DNA network.

Corrosion Reviews, 1996

... Frankel, Gerald S. / Gileadi, Eliezer / Han, En-Hou / Hassel, Achim W. / Kelly, Robert G. / K... more ... Frankel, Gerald S. / Gileadi, Eliezer / Han, En-Hou / Hassel, Achim W. / Kelly, Robert G. / Kim, Kyoo Young / Lunarska, Ellina / Marcus, Philippe / Maruyama, Toshio / Mudali, U. Kamachi / Newman, Roger / Olive, Jean-Marc / Rebak, Raul B. / Revie, R. Winston / Schmuki, Patrik ...

Memorias Do Instituto Oswaldo Cruz, 2002

Here we have characterized Leishmania major (Friedlin) telomeric terminus (the very end) using re... more Here we have characterized Leishmania major (Friedlin) telomeric terminus (the very end) using recombinants obtained by a vector-adaptor cloning protocol. As in L. donovani, the last nine nucleotides of L. major terminus are 5'-GGTTAGGGT-OH 3', differing from Trypanosoma cruzi and T. brucei terminus 5'GGGTTAGGG-OH 3', thus indicating that these sequences are genus specific. We have also made a comparative analysis between L. major and L. donovani telomere-associated sequences, and described a novel non-repeated telomeric associated sequence common to L. major low molecular weight chromosomal bands.

Inapparent infections of Trypanosoma cruzi were detected in symptomless seropositive people livin... more Inapparent infections of Trypanosoma cruzi were detected in symptomless seropositive people living in close proximity, and under the same conditions of risk, to patients with acute Chagas disease. Similar infections were also detected in sera samples of people from 25 villages of western Venezuela where Chagas disease is endemic. Seropositivity in all the 1,251 studied samples was established by use of 3 serological methods (direct agglutination test, indirect immunofluorescence antibody test, and enzyme-linked immunosorbent assay). Each seropositive sample was tested for detection of anti-T. cruzi-specific immunoglobulin (Ig) M and IgG levels and specific T. cruzi infection by molecular methodology (polymerase chain reaction assay). The combined analysis of the serologic (IgM and IgG levels), molecular (specific T. cruzi DNA), and statistical findings demonstrated the existence of a different stage of T. cruzi infection in asymptomatic patients, which is suggested to be recognized as inapparent infection. Its definition, significance, and comparison with typical Chagas disease phases are presented, and its potential epidemiological importance is discussed.

A clinical, parasitologic, and serologic study carried out between 1988 and 1996 on 59 acute-phas... more A clinical, parasitologic, and serologic study carried out between 1988 and 1996 on 59 acute-phase patients in areas of western Venezuela where Chagas' disease is endemic showed 19 symptomatic patterns or groups of symptoms appearing in combination with different frequencies. The symptomatic pattern with the highest frequency was that showing simultaneously fever, myalgia, headache, and Romaña's sign, which was detected in 20% of the acute-phase patients. Asymptomatic individuals and patients with fever as the only sign of the disease made up 15% and 11.9% of the total acute cases, respectively. Statistical correlation analysis revealed that xenodiagnosis and hemoculture were the most reliable and concordant of the five parasitologic methods used; these two methods also showed the highest proportions in detecting any clinical symptomatic pattern in acute-phase patients. A similar high reliability and concordance was obtained with a direct agglutination test, an indirect immunofluorescent antibody test, and an ELISA as serologic tests, which also showed a higher proportion of positive detection of clinical patterns than parasitologic methods (P Ͻ 0.001). It is recommended that individuals coming from endemic areas showing mild and/or severe clinical manifestations should be suspected of being in contact or having been in contact with Trypanosoma cruzi, be referred for parasitologic and serologic evaluations to confirm the presumptive clinical diagnosis of acute Chagas' disease, and start specific treatment. The epidemiologic implications of the present findings are discussed and the use of similar methodology to evaluate other areas where Chagas' disease is endemic is suggested.