KARLA Y ACOSTA-VIANA | Universidad Autonoma de Yucatan (original) (raw)

Papers by KARLA Y ACOSTA-VIANA

American trypanosomiasis is a zoonosis of worldwide medical importance and currently there is no ... more American trypanosomiasis is a zoonosis of worldwide medical importance and currently there is no effective treatment in chronic patients, hence the importance of the study of protein function of the parasite with the objective of finding new drug targets and to know better the biology of the agent causal (Trypanosoma cruzi). T. cruzi is an RNAi-negative parasite, therefore the silencing genes strategies by RNAi is not possible; for that reason, antibodies may be taken as a tool for studying the parasite proteins function by blocking these molecules with specific antibodies. The aim of this work was to establish a methodology for antibody delivery (antibody transfection) into viable parasites. We used anti-cyclin-A antibody (human origin) in western blot assay with epimastigote of T. cruzi proteins and this recognized a 55 kDa polypeptide. Several methods for antibody transfection (electroporation, saponin permeabilization and a lipid-based formulation) were tested. The first two methods were unsuccessful. In electroporation was impossible to visualize the antibody inside parasites and with saponin permeabilization, antibodies were successfully introduced, but with loss of parasites viability. The lipid-based formulation method forms noncovalent complexes with antibodies. These complexes are internalized by cells and antibodies are released into the cytoplasm. With this method, a successful antibody delivery was achieved. Anti-cyclin antibodies were visualized in the cytoplasm from fixed transfected parasites (immunofluorescence assays). At 24 h post-transfection, parasites maintained their viability (90%) and were able to arrest the cell cycle in G0/G1-phase of cultured epimastigotes (cell population in creased in G0/G1-phase from 50.5% to 66.2% and decreased in S-phase from 47.2% to 26%). It was also observed that anti-cyclin-A antibodies inhibit the parasite population doubling (p < 0.05, 95% CI). This is the first report of antibody-delivery into viable epimastigote forms of T. cruzi, with a simple and cheap technique, which will allows carrying out further studies of this protozoan.

pubmedcentralcanada.ca

The antiprotozoal activity in vivo against Trypanosoma cruzi of (8-hydroxymethylen)-trieicosanyl ... more The antiprotozoal activity in vivo against Trypanosoma cruzi of (8-hydroxymethylen)-trieicosanyl acetate was evaluated in BALB/c mice during the acute phase of Chagas' disease (15 days after infection). Animals were treated during 15 days at doses of 16.8 and 33.6 µg/g, reduced parasitemia of 77.6 and 64.1% was observed respectively, in comparison with positive control mice (allopurinol 8.5 µg/g) which reduced only 29.7%. Also, amastigote nests in cardiac tissue were significant reduced in treated mice groups. The regression of effect induced after the suppression of the treatment with the compound was evaluated; animals were infected and simultaneously began the treatment with the compound during 20 days (16.8 and 33.6 µg/g). Mice were monitored after the end of the treatment for one more week. A good antitrypanosomal response was observed (66.1 and 68.9% less than untreated mice) during treatment, but 8 days after suspension of treatment, parasitemia level increased, reducing only 58.6 and 56.29 % respectively in treated animals compared with no treated.

Vector-Borne and …, 2011

A cross-sectional study was developed to determine anti-Toxoplasma gondii immunoglobulin G (IgG) ... more A cross-sectional study was developed to determine anti-Toxoplasma gondii immunoglobulin G (IgG) and IgM antibodies from 80 persons aged 18-21 years without a history of previous contact with cats. Individuals who consented to take part in the survey were served with a questionnaire to obtain response on their eating habits. Blood samples were taken and specific IgM and IgG antibodies against T. gondii were measured by indirect enzyme-linked immunoassay. Seropositivity was found in 29 (37%) and 20 (25%) of 80 persons for IgM and IgG, respectively. Of the cases, 14 (18%) of 80 were positive to both IgM and IgG T. gondii antibodies. A significant association of IgM seropositivity was found in people consuming pork (p-value = 0.04) and wildlife meat (odds ratio = 4.5; confidence intervals = 1.47-14.25; p-value = 0.009). The presence of specific IgG and IgM antibodies in the studied population indicate previous contact and/or recent infections with T. gondii despite avoiding direct contact with cats. Ingestion of pork and meat from wild animals appears to be playing a key role in transmitting the parasite.

… on Infectious Diseases, 2012

The aim of this study was to determine the prevalence and risk factors associated with Toxoplasma... more The aim of this study was to determine the prevalence and risk factors associated with Toxoplasma gondii infection in domestic cats using an indirect-ELISA (IgM and IgG) and PCR. Samples collected from 220 cats from Merida, Yucatan, Mexico, were analyzed. Cases were reported as acute or chronic. Cases when positive to IgM and IgG and PCR were considered as reactivated chronic infection. Risk factors (sex, age, body condition, diet access to hunting, and number of cats in home) were assessed with a multivariate analysis, 75.5% (166/220) of the cats were IgM and 91.8% (202/220) IgG-seropositive and 79% were PCRpositive (173/220). Number of cats per household and low body condition score were associated with reactivated chronic infection (P < 0.05). It is concluded that T. gondii is scattered in the studied population with several periods of reinfection, and therefore an environmental contamination with infecting oocysts exists and there are intrinsic associated factors in cats that increase the risk of becoming infected.

African Journal of …, 2011

Antitrypanosomal activity of chloroform extract of Senna villosa leaves was evaluated in the sub ... more Antitrypanosomal activity of chloroform extract of Senna villosa leaves was evaluated in the sub acute phase of mice infected with Trypanosoma cruzi. Oral doses of 3.3, 6.6 and 13.2 µg/g were tested during 15 days on infected mice BALB/c, beginning treatment 40 days after infection to evaluate specifically the antitrypanosomal activity over the amastigote form of the parasite. Two different amount of parasites (100 and 500) were inoculated to 25 mice for each doses tested. At the end of the assay the animals were sacrificed and cardiac and skeletal tissue sections were stained with hematoxylin-eosin (HE) for identification and quantification of amastigote nest. In mice infected with 100 parasites, a significant reduction in the number of amastigote nest was observed in cardiac tissue of treated animals at all doses evaluated (p<0.05). An important reduction of amastigote nest was also observed in treated animals and infected with 500 parasites in comparison with no treated mice or treated with allopurinol.

Fuel and Energy Abstracts, 2011

The effect of chloroform extracts from seeds of the papaya plant (Carica papaya) on the spermatic... more The effect of chloroform extracts from seeds of the papaya plant (Carica papaya) on the spermatic characteristics of dogs was evaluated at doses of 50, 100 and 150 mg/kg, Groups 1, 2, and 3, respectively. Structural and ultrastructural changes in sperm cells and testicular parenchyma were also evaluated, and possible side effects were noted. Significant reductions in sperm concentration and motility were observed starting from Days 60 and 75, respectively, in all treated groups (P < 0.05), but no azoospermia was noted. A mild osmotic diarrhea occurred in dogs from Group 3 (150 mg/kg), although blood variables were within the normal range of a clinically healthy dog. Arrested spermatogenesis was observed in the seminiferous tubules of all treated groups, and vacuolization and signs of Sertoli cell degeneration were detected in all treated groups, particularly in Group 3 (150 mg/kg). Selective damage to Sertoli cells induced by the extract occurred in all treated groups independently of the extract concentration. Alteration of the epididymal environment may reduce the motility of sperm cells, considering that their structure was normal. Sperm characteristics in treated animals were considered to be similar to those of sub-fertile dogs. However, these effects may be temporary, and dogs may recover normal sperm characteristics when the extract is withdrawn.

African Journal of …, 2011

The antiprotozoal activity in vivo against Trypanosoma cruzi of (8-hydroxymethylen)-trieicosanyl ... more The antiprotozoal activity in vivo against Trypanosoma cruzi of (8-hydroxymethylen)-trieicosanyl acetate was evaluated in BALB/c mice during the acute phase of Chagas' disease (15 days after infection). Animals were treated during 15 days at doses of 16.8 and 33.6 µg/g, reduced parasitemia of 77.6 and 64.1% was observed respectively, in comparison with positive control mice (allopurinol 8.5 µg/g) which reduced only 29.7%. Also, amastigote nests in cardiac tissue were significant reduced in treated mice groups. The regression of effect induced after the suppression of the treatment with the compound was evaluated; animals were infected and simultaneously began the treatment with the compound during 20 days (16.8 and 33.6 µg/g). Mice were monitored after the end of the treatment for one more week. A good antitrypanosomal response was observed (66.1 and 68.9% less than untreated mice) during treatment, but 8 days after suspension of treatment, parasitemia level increased, reducing only 58.6 and 56.29 % respectively in treated animals compared with no treated.

Parasitology Research, 2012

Ethanol extracts of Senna villosa, Serjania yucatanensis, Byrsonima bucidaefolia, and Bourreria p... more Ethanol extracts of Senna villosa, Serjania yucatanensis, Byrsonima bucidaefolia, and Bourreria pulchra were evaluated for their in vitro activity against epimastigotes and trypomastigotes of Trypanosoma cruzi. Results showed that the leaf extracts of S. yucatanensis and B. pulchra were the most active against epimastigotes (IC(100) = 100 μg/mL) and trypomastigotes of T. cruzi (95% or more reduction in the number of parasites at 100 and 50 μg/mL). However, only the leaf extract of S. yucatanensis showed significant trypanocidal activity when tested in vivo, reducing 75% of the parasitemia in infected mice at 100 mg/kg. This same extract inhibited the egress of trypomastigotes from infected cells and proved not to be cytotoxic (IC(50) = 318.8 ± 2.3 μg/mL).

Transboundary and Emerging Diseases, 2010

American trypanosomiasis is an important zoonotic disease which affects more than 15 million pers... more American trypanosomiasis is an important zoonotic disease which affects more than 15 million persons in America. In Mexico, Chagas’ disease is widely distributed in the country mostly in states with tropical weather conditions, including Yucatan. A cross-sectional study was performed on serum samples from 35 dogs and their owners (n = 75) from the south area of Merida city. Specific IgG antibodies against Trypanosoma cruzi (T. cruzi) using enzyme-linked immunosorbent assay, Immunofluorescence antibody test (IFI) and Western blot (WB) were detected. The overall percentage of seropositivity was 34% in dogs and 8% for sampled owners. Some owners brought samples of insect vectors found in their households, which were kept with BALB/c mice as a source of food and which were evaluated by polymerase chain reaction. All tested insects were positive to T. cruzi, and BALB/C mice were IFI and WB positive after 45 days in contact with these vectors. Further investigations showed that there is a high risk of infection with Chagas disease in dogs which spend the night outdoors (P < 0.05), with low body conditions score and older dogs. Risk factors identified to be associated to the infection in owners were gender and occupation (bricklayers, P < 0.05). The presence of seropositive dogs in houses where vectors are well-adapted represents a high risk for humans to become infected when bitten by a vector infected by a positive dog.

Tecnología del agua, 1999

Phytomedicine, 2008

A white solid compound was isolated from the chloroform extract of the leaves of Senna villosa. T... more A white solid compound was isolated from the chloroform extract of the leaves of Senna villosa. The material was identified by 1H-NMR, 13C-NMR, IR and EM methods as (8-hydroxymethylen)-trieicosanyl acetate, a new compound with biological activity, which was tested in vitro at concentrations of 1.65, 3.3 and 6.6 μg/ml for inhibition of the growth of Trypanosoma cruzi epimastigotes and tripomastigotes. We observed inhibition of growth at all concentrations tested, and the effect at concentrations of 3.3 and 6.6 μg/ml was greater than that of gentian violet (positive control). At the concentration of 6.6 μg/ml, the compound showed the greatest inhibitory effect against the growth of both forms of the parasite.

Veterinary Parasitology, 2011

The presence of cats in the farms is considered a risk factor for the infection of pigs with Toxo... more The presence of cats in the farms is considered a risk factor for the infection of pigs with Toxoplasma gondii (T. gondii). Cats eliminate oocysts that contaminate food, water and promote the infection of host reservoir such as rodents and birds among others that are also involved in the infection of pigs. The objective of this study was to assess the dynamic of infection of T. gondii in seronegative weaned pigs from weaning to 20 weeks of age from two farms from an endemic region, one with high and low density of cats. A cohort study was performed in 64 pigs, 31 newly weaned pigs on a farm with a high density of cats (FA) and 33 newly-weaned pigs on a farm with a low density of cats (FB). Blood samples were collected every 14 days to determine the presence of IgG antibodies against T. gondii in the serum using an indirect ELISA test. True incidence rate (TIV), cumulative incidence (AI) and relative risk (RR) was calculated. The age of seroconversion was determined by using survival tables; both farms were compared with Long-Rank test. In FA 97.5% of the pigs seroconverted at the second sampling and 100% at the third sampling, while in the FB all pigs seroconverted to the fourth sampling. The TIV was 0.67 and 0.43 for FA and FB respectively, during the first four weeks at risk. A RR of 1.5 (1.04–2.39) was obtained (p < 0.05). Animals of the FA had a higher risk of infection compared with the FB, however, all animals included in the study had contact with the agent. Infection with T. gondii was rapidly distributed in both farms, regardless of the relative density of cats observed during the study. These results suggest a high environmental contamination with oocysts in the facilities of both farms probably due to the fact that T. gondii infection is endemic in the area where the farms are located, allow proper establishment of the etiological agent. The points of prevention and control strategies to avoid exposure of pigs to T. gondii in an endemic area should focus on the control of cats and rodents.

Pharmaceutical Biology, 2010

The activity of an (8-hydroxymethylen)-trieicosanyl acetate compound obtained from chloroform ext... more The activity of an (8-hydroxymethylen)-trieicosanyl acetate compound obtained from chloroform extracts of Senna villosa (Mill.) H.S. Irwin &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Barneby (Leguminosae) against Trypanosoma cruzi was evaluated in vivo. Oral doses of 2.1, 8.4, and 33.6 microg/g were tested for 28 days in BALB/c mice infected with T. cruzi. Reduced parasitemia levels of 70.5%, 73.8%, and 80.9%, respectively, were observed. A significant reduction in amastigote nests was detected in the cardiac tissue of treated animals at doses of 8.4 and 33.6 microg/g. The LD50 of (8-hydroxymethylen)-trieicosanyl acetate was impossible to determine because none of the animals died, even at oral doses of 5000 microg/g; consequently, it was impossible to determine the acute oral toxicity in vivo.

Archives of Medical Research, 2002

Background. The Trypanosomatidae family possesses one of the most unusual DNAs found in nature: t... more Background. The Trypanosomatidae family possesses one of the most unusual DNAs found in nature: the kinetoplast genome. It consists of a few dozen maxicircles that encode for some subunits of mitochondrial enzymes and rRNAs in a cryptic pattern and thousands of minicircles that encode for the guide RNAs (gRNAs), all catenated and constituting a dense network. The complexity of kinetoplast genome based on its intricate DNA structure is well known; however, only a small number of proteins associated with kinetoplast DNA (kDNA) have been described, and the majority are related with the replication process. Methods. We describe the protein profile obtained using formaldehyde as a cross-linking agent to obtain the kinetoplast DNA-protein complex, and Southwestern assay to identify the kDNA binding proteins present in the complex. Results. We identified seven proteins eluted from the kDNA complex fixed by formaldehyde. Polyclonal antiserum developed against the kDNA-protein complex recognized only four proteins in crude extracts of epimastigote stage, suggesting immunogenic differences among these proteins and/or their availability in the kinetoplast genome. Southwestern assay using minicircle fragments showed nine kDNA binding proteins in crude extracts of Trypanosoma cruzi epimastigote. Conclusions. We describe several proteins associated with the kDNA. Some could be involved in the essential process for parasite life and also could be a good target for drug or vaccine development. The results contribute to understanding the organization of the kinetoplast genome.

Acta Tropica, 2000

Knowledge regarding kinetoplast DNA organization in all members of the Trypanosomatid family is i... more Knowledge regarding kinetoplast DNA organization in all members of the Trypanosomatid family is incomplete. Recently, the presence of kinetoplast-associated proteins in condensing kDNA networks in Crithidia fasciculata has been described and a role for these proteins in the maintenance of these complex structures was suggested. To investigate the presence of protein components in Trypanosoma cruzi kinetoplast, we previously described seven epimastigote kinetoplast-associated proteins. We report here the existence of kinetoplast binding proteins in amastigote and trypomastigote stages of T. cruzi, which could bind both mini and maxicircles components with a stage specific elements for every infective form of the parasite. We propose three major classes of kinetoplast-associated proteins related to the basic processes of this intricate disc structure and suggest a possible function of these binding proteins in the T. cruzi mitochondrial DNA organization.

Vector-borne and Zoonotic Diseases, 2010

This investigation determined the presence and prevalence of the zoonotic agents Leptospira inter... more This investigation determined the presence and prevalence of the zoonotic agents Leptospira interrogans, Trypanosoma cruzi, and Aspergillus spp. in the stray dog population (a total of 224 stray dogs) in an urban area of Southern Mexico. Blood serum samples were taken from all dogs, and root hair samples were taken from dogs with skin lesions and partial alopecia. IgG antibodies for L. interrogans from 10 serovars were detected using the microscopic agglutination test. Immunofluorescence antibody test and Western blot assay were used for serologic diagnosis of T. cruzi. The Sabouraud medium was used to isolate Aspergillus spp. Prevalence of L. interrogans was 4.9%, which was determined by identifying only serovars Pyrogenes, which accounted for 3.6%, and Tarassovi, which constituted 1.3%, with titers from 1:100 to 1:800. Additionally, T. cruzi antibodies were detected in 4.5% of the dogs. Skin lesions were found in 43% of the dogs (98/224), and 35 cultures were positive for Aspergillus spp. (35.7%, p &amp;amp;amp;amp;amp;amp;lt; 0.05, 95% confidence interval 2.45-3.67), identified as A. niger (82.8%), A. flavus (14.3%), and A. terreus (2.9%). This study demonstrates the presence of certain zoonotic agents (bacteria, protozoa, and fungi) in stray dogs living within the studied area. Dogs play an important role in the transmission of diseases that are potentially harmful to humans. Although the prevalence of canine leptospirosis and trypanosomiasis is not high in Southern Mexico compared with other tropical regions of Mexico, the presence of these zoonotic agents in the stray dog population demonstrates that the stray dog population in this region is a significant reservoir and potential source of infection in humans. Special care should be taken when handling stray dogs that exhibit skin lesions with partial alopecia, since a pathological Aspergillus sp. fungus may be present.

Rev Biomed, 1996

Actualmente son escasas las áreas del campo de la biología en donde no se contemple el uso de téc... more Actualmente son escasas las áreas del campo de la biología en donde no se contemple el uso de técnicas de biología molecular para diversos menesteres, los cuales van desde el diagnóstico preciso y temprano de infecciones por organismos patógenos en plantas, animales y humanos, hasta la generación de vacunas y fármacos específicos y el mejoramiento de especies por medio de ingeniería genética. Esta revisión pretende dar un panorama acerca de uno de los mecanismos más importantes dentro de las células tanto eucariotas como procariotas : el reconocimiento y unión de proteínas a secuencias de DNA.

Transfusion Medicine, 2005

summary. Hepatitis B virus (HBV) may be present in serum even when negative for HBV surface anti... more summary. Hepatitis B virus (HBV) may be present in serum even when negative for HBV surface antigen (HBsAg). If routine screening of sera for anti-HBV core antigen (anti-HBc) is not done, low-level HBV viraemia may not be identified. A study was done on the presence of HBV DNA in serum samples from Mexican blood donors negative for HBsAg. Sera from 158 volunteer blood donors, negative for HBsAg and anti-HBs, but positive for anti-HBc, were analysed using nested polymerase chain reaction (PCR). HBV DNA was detected in sera from 13 (8·23%) of the 158. Specificity of the PCR-amplified products was corroborated using Southern blot. Single strand conformation polymorphism (SSCP) analysis showed identical SSCP-banding patterns for all 13 PCR products, suggesting similar cDNA sequences. Occult HBV infection was observed in approximately 8% of anti-HBc only donors. The absence of HBsAg in the blood of apparently healthy individuals may not be sufficient to ensure lack of circulating HBV, and blood containing anti-HBc only may be infectious until proven otherwise.

American trypanosomiasis is a zoonosis of worldwide medical importance and currently there is no ... more American trypanosomiasis is a zoonosis of worldwide medical importance and currently there is no effective treatment in chronic patients, hence the importance of the study of protein function of the parasite with the objective of finding new drug targets and to know better the biology of the agent causal (Trypanosoma cruzi). T. cruzi is an RNAi-negative parasite, therefore the silencing genes strategies by RNAi is not possible; for that reason, antibodies may be taken as a tool for studying the parasite proteins function by blocking these molecules with specific antibodies. The aim of this work was to establish a methodology for antibody delivery (antibody transfection) into viable parasites. We used anti-cyclin-A antibody (human origin) in western blot assay with epimastigote of T. cruzi proteins and this recognized a 55 kDa polypeptide. Several methods for antibody transfection (electroporation, saponin permeabilization and a lipid-based formulation) were tested. The first two methods were unsuccessful. In electroporation was impossible to visualize the antibody inside parasites and with saponin permeabilization, antibodies were successfully introduced, but with loss of parasites viability. The lipid-based formulation method forms noncovalent complexes with antibodies. These complexes are internalized by cells and antibodies are released into the cytoplasm. With this method, a successful antibody delivery was achieved. Anti-cyclin antibodies were visualized in the cytoplasm from fixed transfected parasites (immunofluorescence assays). At 24 h post-transfection, parasites maintained their viability (90%) and were able to arrest the cell cycle in G0/G1-phase of cultured epimastigotes (cell population in creased in G0/G1-phase from 50.5% to 66.2% and decreased in S-phase from 47.2% to 26%). It was also observed that anti-cyclin-A antibodies inhibit the parasite population doubling (p < 0.05, 95% CI). This is the first report of antibody-delivery into viable epimastigote forms of T. cruzi, with a simple and cheap technique, which will allows carrying out further studies of this protozoan.

pubmedcentralcanada.ca

The antiprotozoal activity in vivo against Trypanosoma cruzi of (8-hydroxymethylen)-trieicosanyl ... more The antiprotozoal activity in vivo against Trypanosoma cruzi of (8-hydroxymethylen)-trieicosanyl acetate was evaluated in BALB/c mice during the acute phase of Chagas' disease (15 days after infection). Animals were treated during 15 days at doses of 16.8 and 33.6 µg/g, reduced parasitemia of 77.6 and 64.1% was observed respectively, in comparison with positive control mice (allopurinol 8.5 µg/g) which reduced only 29.7%. Also, amastigote nests in cardiac tissue were significant reduced in treated mice groups. The regression of effect induced after the suppression of the treatment with the compound was evaluated; animals were infected and simultaneously began the treatment with the compound during 20 days (16.8 and 33.6 µg/g). Mice were monitored after the end of the treatment for one more week. A good antitrypanosomal response was observed (66.1 and 68.9% less than untreated mice) during treatment, but 8 days after suspension of treatment, parasitemia level increased, reducing only 58.6 and 56.29 % respectively in treated animals compared with no treated.

Vector-Borne and …, 2011

A cross-sectional study was developed to determine anti-Toxoplasma gondii immunoglobulin G (IgG) ... more A cross-sectional study was developed to determine anti-Toxoplasma gondii immunoglobulin G (IgG) and IgM antibodies from 80 persons aged 18-21 years without a history of previous contact with cats. Individuals who consented to take part in the survey were served with a questionnaire to obtain response on their eating habits. Blood samples were taken and specific IgM and IgG antibodies against T. gondii were measured by indirect enzyme-linked immunoassay. Seropositivity was found in 29 (37%) and 20 (25%) of 80 persons for IgM and IgG, respectively. Of the cases, 14 (18%) of 80 were positive to both IgM and IgG T. gondii antibodies. A significant association of IgM seropositivity was found in people consuming pork (p-value = 0.04) and wildlife meat (odds ratio = 4.5; confidence intervals = 1.47-14.25; p-value = 0.009). The presence of specific IgG and IgM antibodies in the studied population indicate previous contact and/or recent infections with T. gondii despite avoiding direct contact with cats. Ingestion of pork and meat from wild animals appears to be playing a key role in transmitting the parasite.

… on Infectious Diseases, 2012

The aim of this study was to determine the prevalence and risk factors associated with Toxoplasma... more The aim of this study was to determine the prevalence and risk factors associated with Toxoplasma gondii infection in domestic cats using an indirect-ELISA (IgM and IgG) and PCR. Samples collected from 220 cats from Merida, Yucatan, Mexico, were analyzed. Cases were reported as acute or chronic. Cases when positive to IgM and IgG and PCR were considered as reactivated chronic infection. Risk factors (sex, age, body condition, diet access to hunting, and number of cats in home) were assessed with a multivariate analysis, 75.5% (166/220) of the cats were IgM and 91.8% (202/220) IgG-seropositive and 79% were PCRpositive (173/220). Number of cats per household and low body condition score were associated with reactivated chronic infection (P < 0.05). It is concluded that T. gondii is scattered in the studied population with several periods of reinfection, and therefore an environmental contamination with infecting oocysts exists and there are intrinsic associated factors in cats that increase the risk of becoming infected.

African Journal of …, 2011

Antitrypanosomal activity of chloroform extract of Senna villosa leaves was evaluated in the sub ... more Antitrypanosomal activity of chloroform extract of Senna villosa leaves was evaluated in the sub acute phase of mice infected with Trypanosoma cruzi. Oral doses of 3.3, 6.6 and 13.2 µg/g were tested during 15 days on infected mice BALB/c, beginning treatment 40 days after infection to evaluate specifically the antitrypanosomal activity over the amastigote form of the parasite. Two different amount of parasites (100 and 500) were inoculated to 25 mice for each doses tested. At the end of the assay the animals were sacrificed and cardiac and skeletal tissue sections were stained with hematoxylin-eosin (HE) for identification and quantification of amastigote nest. In mice infected with 100 parasites, a significant reduction in the number of amastigote nest was observed in cardiac tissue of treated animals at all doses evaluated (p<0.05). An important reduction of amastigote nest was also observed in treated animals and infected with 500 parasites in comparison with no treated mice or treated with allopurinol.

Fuel and Energy Abstracts, 2011

The effect of chloroform extracts from seeds of the papaya plant (Carica papaya) on the spermatic... more The effect of chloroform extracts from seeds of the papaya plant (Carica papaya) on the spermatic characteristics of dogs was evaluated at doses of 50, 100 and 150 mg/kg, Groups 1, 2, and 3, respectively. Structural and ultrastructural changes in sperm cells and testicular parenchyma were also evaluated, and possible side effects were noted. Significant reductions in sperm concentration and motility were observed starting from Days 60 and 75, respectively, in all treated groups (P < 0.05), but no azoospermia was noted. A mild osmotic diarrhea occurred in dogs from Group 3 (150 mg/kg), although blood variables were within the normal range of a clinically healthy dog. Arrested spermatogenesis was observed in the seminiferous tubules of all treated groups, and vacuolization and signs of Sertoli cell degeneration were detected in all treated groups, particularly in Group 3 (150 mg/kg). Selective damage to Sertoli cells induced by the extract occurred in all treated groups independently of the extract concentration. Alteration of the epididymal environment may reduce the motility of sperm cells, considering that their structure was normal. Sperm characteristics in treated animals were considered to be similar to those of sub-fertile dogs. However, these effects may be temporary, and dogs may recover normal sperm characteristics when the extract is withdrawn.

African Journal of …, 2011

The antiprotozoal activity in vivo against Trypanosoma cruzi of (8-hydroxymethylen)-trieicosanyl ... more The antiprotozoal activity in vivo against Trypanosoma cruzi of (8-hydroxymethylen)-trieicosanyl acetate was evaluated in BALB/c mice during the acute phase of Chagas' disease (15 days after infection). Animals were treated during 15 days at doses of 16.8 and 33.6 µg/g, reduced parasitemia of 77.6 and 64.1% was observed respectively, in comparison with positive control mice (allopurinol 8.5 µg/g) which reduced only 29.7%. Also, amastigote nests in cardiac tissue were significant reduced in treated mice groups. The regression of effect induced after the suppression of the treatment with the compound was evaluated; animals were infected and simultaneously began the treatment with the compound during 20 days (16.8 and 33.6 µg/g). Mice were monitored after the end of the treatment for one more week. A good antitrypanosomal response was observed (66.1 and 68.9% less than untreated mice) during treatment, but 8 days after suspension of treatment, parasitemia level increased, reducing only 58.6 and 56.29 % respectively in treated animals compared with no treated.

Parasitology Research, 2012

Ethanol extracts of Senna villosa, Serjania yucatanensis, Byrsonima bucidaefolia, and Bourreria p... more Ethanol extracts of Senna villosa, Serjania yucatanensis, Byrsonima bucidaefolia, and Bourreria pulchra were evaluated for their in vitro activity against epimastigotes and trypomastigotes of Trypanosoma cruzi. Results showed that the leaf extracts of S. yucatanensis and B. pulchra were the most active against epimastigotes (IC(100) = 100 μg/mL) and trypomastigotes of T. cruzi (95% or more reduction in the number of parasites at 100 and 50 μg/mL). However, only the leaf extract of S. yucatanensis showed significant trypanocidal activity when tested in vivo, reducing 75% of the parasitemia in infected mice at 100 mg/kg. This same extract inhibited the egress of trypomastigotes from infected cells and proved not to be cytotoxic (IC(50) = 318.8 ± 2.3 μg/mL).

Transboundary and Emerging Diseases, 2010

American trypanosomiasis is an important zoonotic disease which affects more than 15 million pers... more American trypanosomiasis is an important zoonotic disease which affects more than 15 million persons in America. In Mexico, Chagas’ disease is widely distributed in the country mostly in states with tropical weather conditions, including Yucatan. A cross-sectional study was performed on serum samples from 35 dogs and their owners (n = 75) from the south area of Merida city. Specific IgG antibodies against Trypanosoma cruzi (T. cruzi) using enzyme-linked immunosorbent assay, Immunofluorescence antibody test (IFI) and Western blot (WB) were detected. The overall percentage of seropositivity was 34% in dogs and 8% for sampled owners. Some owners brought samples of insect vectors found in their households, which were kept with BALB/c mice as a source of food and which were evaluated by polymerase chain reaction. All tested insects were positive to T. cruzi, and BALB/C mice were IFI and WB positive after 45 days in contact with these vectors. Further investigations showed that there is a high risk of infection with Chagas disease in dogs which spend the night outdoors (P < 0.05), with low body conditions score and older dogs. Risk factors identified to be associated to the infection in owners were gender and occupation (bricklayers, P < 0.05). The presence of seropositive dogs in houses where vectors are well-adapted represents a high risk for humans to become infected when bitten by a vector infected by a positive dog.

Tecnología del agua, 1999

Phytomedicine, 2008

A white solid compound was isolated from the chloroform extract of the leaves of Senna villosa. T... more A white solid compound was isolated from the chloroform extract of the leaves of Senna villosa. The material was identified by 1H-NMR, 13C-NMR, IR and EM methods as (8-hydroxymethylen)-trieicosanyl acetate, a new compound with biological activity, which was tested in vitro at concentrations of 1.65, 3.3 and 6.6 μg/ml for inhibition of the growth of Trypanosoma cruzi epimastigotes and tripomastigotes. We observed inhibition of growth at all concentrations tested, and the effect at concentrations of 3.3 and 6.6 μg/ml was greater than that of gentian violet (positive control). At the concentration of 6.6 μg/ml, the compound showed the greatest inhibitory effect against the growth of both forms of the parasite.

Veterinary Parasitology, 2011

The presence of cats in the farms is considered a risk factor for the infection of pigs with Toxo... more The presence of cats in the farms is considered a risk factor for the infection of pigs with Toxoplasma gondii (T. gondii). Cats eliminate oocysts that contaminate food, water and promote the infection of host reservoir such as rodents and birds among others that are also involved in the infection of pigs. The objective of this study was to assess the dynamic of infection of T. gondii in seronegative weaned pigs from weaning to 20 weeks of age from two farms from an endemic region, one with high and low density of cats. A cohort study was performed in 64 pigs, 31 newly weaned pigs on a farm with a high density of cats (FA) and 33 newly-weaned pigs on a farm with a low density of cats (FB). Blood samples were collected every 14 days to determine the presence of IgG antibodies against T. gondii in the serum using an indirect ELISA test. True incidence rate (TIV), cumulative incidence (AI) and relative risk (RR) was calculated. The age of seroconversion was determined by using survival tables; both farms were compared with Long-Rank test. In FA 97.5% of the pigs seroconverted at the second sampling and 100% at the third sampling, while in the FB all pigs seroconverted to the fourth sampling. The TIV was 0.67 and 0.43 for FA and FB respectively, during the first four weeks at risk. A RR of 1.5 (1.04–2.39) was obtained (p < 0.05). Animals of the FA had a higher risk of infection compared with the FB, however, all animals included in the study had contact with the agent. Infection with T. gondii was rapidly distributed in both farms, regardless of the relative density of cats observed during the study. These results suggest a high environmental contamination with oocysts in the facilities of both farms probably due to the fact that T. gondii infection is endemic in the area where the farms are located, allow proper establishment of the etiological agent. The points of prevention and control strategies to avoid exposure of pigs to T. gondii in an endemic area should focus on the control of cats and rodents.

Pharmaceutical Biology, 2010

The activity of an (8-hydroxymethylen)-trieicosanyl acetate compound obtained from chloroform ext... more The activity of an (8-hydroxymethylen)-trieicosanyl acetate compound obtained from chloroform extracts of Senna villosa (Mill.) H.S. Irwin &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Barneby (Leguminosae) against Trypanosoma cruzi was evaluated in vivo. Oral doses of 2.1, 8.4, and 33.6 microg/g were tested for 28 days in BALB/c mice infected with T. cruzi. Reduced parasitemia levels of 70.5%, 73.8%, and 80.9%, respectively, were observed. A significant reduction in amastigote nests was detected in the cardiac tissue of treated animals at doses of 8.4 and 33.6 microg/g. The LD50 of (8-hydroxymethylen)-trieicosanyl acetate was impossible to determine because none of the animals died, even at oral doses of 5000 microg/g; consequently, it was impossible to determine the acute oral toxicity in vivo.

Archives of Medical Research, 2002

Background. The Trypanosomatidae family possesses one of the most unusual DNAs found in nature: t... more Background. The Trypanosomatidae family possesses one of the most unusual DNAs found in nature: the kinetoplast genome. It consists of a few dozen maxicircles that encode for some subunits of mitochondrial enzymes and rRNAs in a cryptic pattern and thousands of minicircles that encode for the guide RNAs (gRNAs), all catenated and constituting a dense network. The complexity of kinetoplast genome based on its intricate DNA structure is well known; however, only a small number of proteins associated with kinetoplast DNA (kDNA) have been described, and the majority are related with the replication process. Methods. We describe the protein profile obtained using formaldehyde as a cross-linking agent to obtain the kinetoplast DNA-protein complex, and Southwestern assay to identify the kDNA binding proteins present in the complex. Results. We identified seven proteins eluted from the kDNA complex fixed by formaldehyde. Polyclonal antiserum developed against the kDNA-protein complex recognized only four proteins in crude extracts of epimastigote stage, suggesting immunogenic differences among these proteins and/or their availability in the kinetoplast genome. Southwestern assay using minicircle fragments showed nine kDNA binding proteins in crude extracts of Trypanosoma cruzi epimastigote. Conclusions. We describe several proteins associated with the kDNA. Some could be involved in the essential process for parasite life and also could be a good target for drug or vaccine development. The results contribute to understanding the organization of the kinetoplast genome.

Acta Tropica, 2000

Knowledge regarding kinetoplast DNA organization in all members of the Trypanosomatid family is i... more Knowledge regarding kinetoplast DNA organization in all members of the Trypanosomatid family is incomplete. Recently, the presence of kinetoplast-associated proteins in condensing kDNA networks in Crithidia fasciculata has been described and a role for these proteins in the maintenance of these complex structures was suggested. To investigate the presence of protein components in Trypanosoma cruzi kinetoplast, we previously described seven epimastigote kinetoplast-associated proteins. We report here the existence of kinetoplast binding proteins in amastigote and trypomastigote stages of T. cruzi, which could bind both mini and maxicircles components with a stage specific elements for every infective form of the parasite. We propose three major classes of kinetoplast-associated proteins related to the basic processes of this intricate disc structure and suggest a possible function of these binding proteins in the T. cruzi mitochondrial DNA organization.

Vector-borne and Zoonotic Diseases, 2010

This investigation determined the presence and prevalence of the zoonotic agents Leptospira inter... more This investigation determined the presence and prevalence of the zoonotic agents Leptospira interrogans, Trypanosoma cruzi, and Aspergillus spp. in the stray dog population (a total of 224 stray dogs) in an urban area of Southern Mexico. Blood serum samples were taken from all dogs, and root hair samples were taken from dogs with skin lesions and partial alopecia. IgG antibodies for L. interrogans from 10 serovars were detected using the microscopic agglutination test. Immunofluorescence antibody test and Western blot assay were used for serologic diagnosis of T. cruzi. The Sabouraud medium was used to isolate Aspergillus spp. Prevalence of L. interrogans was 4.9%, which was determined by identifying only serovars Pyrogenes, which accounted for 3.6%, and Tarassovi, which constituted 1.3%, with titers from 1:100 to 1:800. Additionally, T. cruzi antibodies were detected in 4.5% of the dogs. Skin lesions were found in 43% of the dogs (98/224), and 35 cultures were positive for Aspergillus spp. (35.7%, p &amp;amp;amp;amp;amp;amp;lt; 0.05, 95% confidence interval 2.45-3.67), identified as A. niger (82.8%), A. flavus (14.3%), and A. terreus (2.9%). This study demonstrates the presence of certain zoonotic agents (bacteria, protozoa, and fungi) in stray dogs living within the studied area. Dogs play an important role in the transmission of diseases that are potentially harmful to humans. Although the prevalence of canine leptospirosis and trypanosomiasis is not high in Southern Mexico compared with other tropical regions of Mexico, the presence of these zoonotic agents in the stray dog population demonstrates that the stray dog population in this region is a significant reservoir and potential source of infection in humans. Special care should be taken when handling stray dogs that exhibit skin lesions with partial alopecia, since a pathological Aspergillus sp. fungus may be present.

Rev Biomed, 1996

Actualmente son escasas las áreas del campo de la biología en donde no se contemple el uso de téc... more Actualmente son escasas las áreas del campo de la biología en donde no se contemple el uso de técnicas de biología molecular para diversos menesteres, los cuales van desde el diagnóstico preciso y temprano de infecciones por organismos patógenos en plantas, animales y humanos, hasta la generación de vacunas y fármacos específicos y el mejoramiento de especies por medio de ingeniería genética. Esta revisión pretende dar un panorama acerca de uno de los mecanismos más importantes dentro de las células tanto eucariotas como procariotas : el reconocimiento y unión de proteínas a secuencias de DNA.

Transfusion Medicine, 2005

summary. Hepatitis B virus (HBV) may be present in serum even when negative for HBV surface anti... more summary. Hepatitis B virus (HBV) may be present in serum even when negative for HBV surface antigen (HBsAg). If routine screening of sera for anti-HBV core antigen (anti-HBc) is not done, low-level HBV viraemia may not be identified. A study was done on the presence of HBV DNA in serum samples from Mexican blood donors negative for HBsAg. Sera from 158 volunteer blood donors, negative for HBsAg and anti-HBs, but positive for anti-HBc, were analysed using nested polymerase chain reaction (PCR). HBV DNA was detected in sera from 13 (8·23%) of the 158. Specificity of the PCR-amplified products was corroborated using Southern blot. Single strand conformation polymorphism (SSCP) analysis showed identical SSCP-banding patterns for all 13 PCR products, suggesting similar cDNA sequences. Occult HBV infection was observed in approximately 8% of anti-HBc only donors. The absence of HBsAg in the blood of apparently healthy individuals may not be sufficient to ensure lack of circulating HBV, and blood containing anti-HBc only may be infectious until proven otherwise.