RESUMO
Chirality is a geometric property of matter that can be present at different scales, especially at the nanoscale. Here, we investigate the manifestation of chirality in electronic transport through a molecular junction. Spinless electronic transport through a chiral molecular junction is not enantiospecific. However, when a chiral metal cluster, C3-Au34, is attached to the source electrode, a different response is obtained in spinless electronic transport between R and L systems: this indicates the crucial role of chiral clusters in triggering enantiospecific spinless electronic transport. In contrast, when an achiral metal cluster, C3v-Au34, is attached, no change in conductance occurs between enantiomeric systems. Using the non-equilibrium green's function method, we characterized this phenomenon by calculating the transmission and conductance of spin-unpolarized electrons. Our theoretical results highlight the importance of metal clusters with specific sizes and chiral structures in electronic transport and support previously published experimental results that exhibited enantiospecific scanning tunneling measurements with intrinsically chiral tips.
RESUMO
Cutaneous leishmaniasis (CL) is endemic in Campeche state, Mexico. Host and parasite factors are involved in the establishment and development of CL. Host factors include immune response and genetic background. NRAMP1 (Natural Resistance Associated Macrophage Protein 1) is important in innate immunity. Polymorphisms in NRAMP1 have been associated with susceptibility or resistance to infectious and autoimmune diseases. To study the association of NRAMP1 mutations with CL in patients from Calakmul, Campeche, samples from 115 CL patients and 69 samples of healthy people from the same area were evaluated. Five regions in NRAMP1 were amplified and digested, looking for mutations in the promoter region (-524G/C), exon 3 (274C/T), exon 8 (823 C7T), and exon 15 (G/A) and deletion of 4 bp in the 3'UTR region. We found a statistical association between polymorphisms in 3'UTR region and exon 8 and CL [χ2 = 13.26; p < 0.05; OR = 17.00; IC of 95% (2.24-128.99)]. Some patients who needed more than 40 doses of Glucantime® to heal injuries presented mutations in exons 3, 8, and 15. Multiple or ear lesions were not associated with NRAMP1 polymorphism.
Assuntos
Proteínas de Transporte de Cátions/genética , Predisposição Genética para Doença/epidemiologia , Predisposição Genética para Doença/genética , Leishmaniose Cutânea/epidemiologia , Leishmaniose Cutânea/genética , Polimorfismo de Nucleotídeo Único/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Feminino , Marcadores Genéticos/genética , Humanos , Leishmaniose Cutânea/diagnóstico , Masculino , México/epidemiologia , Pessoa de Meia-Idade , Prevalência , Reprodutibilidade dos Testes , Fatores de Risco , Sensibilidade e EspecificidadeRESUMO
Objective. To study cutaneous leishmaniasis (CL), in the Calakmul municipality of the Campeche State, during two years. Materials and methods. Individuals with skin lesions were evaluated. Aspirates taken from the lesions were cultured, PCR was performed to diagnose the Leishmania species. Results. The culture detected 42% of the samples. PCR diagnosed CL in 76% of the samples; of those 38% were from children and 62% from adults. 89% of the patients were infected with L. mexicana; 14.4% with Mexican strains of L. mexicana; 7% with L. braziliensis; 3.6% with L. mexicana and L. braziliensis. The most affected villages with CL were Dos Lagunas Sur with 12.3%, La Mancolona with 6.5% and La Guadalupe with 2.2% of prevalence, respectively. After the treatment with Glucantime, 96% of the patients were healed. Conclusion. CL is an important public health concern in Calakmul, and the parasite causing it belongs to Leishmania mexicana and Leishmania braziliensis complexes.
Objetivo. Estudiar la leishmaniasis cutánea en Calakmul, Campeche, México, durante dos años. Material y métodos. Se estudiaron individuos con lesiones cutáneas, se tomaron aspirados y se inocularon medios de cultivo; se realizó la técnica de PCR para identificar la especie de Leishmania. Resultados. Los cultivos detectaron 42% de las muestras. Con la PCR se amplificaron 76% de las muestras, 38% fueron tomadas de niños y 62% de adultos. En 89% de las muestras positivas se identificó Leishmania mexicana, en 14.4% cepas mexicanas de L. mexicana, en 7% L. braziliensis y en 3.6% L. mexicana y L. braziliensis. En Dos Lagunas Sur se encontró una prevalencia de 12.3%, en La Mancolona 6.5% y en La Virgen 2.2%. Del total de los pacientes, 96% se curó con Glucantime. Conclusion. La leishmaniasis cutánea es un problema de salud pública en Calakmul y las especies causantes pertenecen a los complejos Leishmania mexicana y Leishmania braziliensis.
Assuntos
Humanos , Animais , Masculino , Feminino , Criança , Adulto , Leishmaniose Cutânea/epidemiologia , Compostos Organometálicos/uso terapêutico , Roedores/parasitologia , Leishmania braziliensis/isolamento & purificação , Indução de Remissão , Leishmania mexicana/isolamento & purificação , Reservatórios de Doenças , Prevalência , DNA de Protozoário/análise , Leishmaniose Cutânea/parasitologia , Geografia Médica , Antimoniato de Meglumina , Meglumina/uso terapêutico , México/epidemiologia , Antiprotozoários/uso terapêuticoRESUMO
OBJECTIVE: To study cutaneous leishmaniasis (CL), in the Calakmul municipality of the Campeche State, during two years. MATERIALS AND METHODS: Individuals with skin lesions were evaluated. Aspirates taken from the lesions were cultured, PCR was performed to diagnose the Leishmania species. RESULTS: The culture detected 42% of the samples. PCR diagnosed CL in 76% of the samples; of those 38% were from children and 62% from adults. 89% of the patients were infected with L. mexicana; 14.4% with Mexican strains of L. mexicana; 7% with L. braziliensis; 3.6% with L. mexicana and L. braziliensis. The most affected villages with CL were Dos Lagunas Sur with 12.3%, La Mancolona with 6.5% and La Guadalupe with 2.2% of prevalence, respectively. After the treatment with Glucantime, 96% of the patients were healed. CONCLUSION: CL is an important public health concern in Calakmul, and the parasite causing it belongs to Leishmania mexicana and Leishmania braziliensis complexes.
Assuntos
Leishmaniose Cutânea/epidemiologia , Adulto , Animais , Antiprotozoários/uso terapêutico , Criança , DNA de Protozoário/análise , Reservatórios de Doenças , Feminino , Geografia Médica , Humanos , Leishmania braziliensis/isolamento & purificação , Leishmania mexicana/isolamento & purificação , Leishmaniose Cutânea/parasitologia , Masculino , Meglumina/uso terapêutico , Antimoniato de Meglumina , México/epidemiologia , Compostos Organometálicos/uso terapêutico , Prevalência , Indução de Remissão , Roedores/parasitologiaRESUMO
This study analyzed DNA minicircles of Mexican isolates of L. (Leishmania) mexicana to look for genetic differences between strains isolated from patients with diffuse cutaneous (DCL) and localized (LCL) leishmaniasis. The kDNA was analyzed using polymerase chain reaction (PCR), restriction fragment polymorphism analysis of the PCR products (PCR-RFLP) and the PCR products were sequenced. In the PCR with primers specific for the subgenus Leishmania, the Mexican isolates gave higher amplification products than the other L. mexicana complex strains and with specific primers for the L. mexicana complex they were poorly amplified. In the PCR-RFLP analysis with the Eco RV, Hae III, and Mbo I endonucleases, the Mexican isolates displayed similar restriction patterns, but different from the patterns of the other members of the L. mexicana complex. In the phylogenetic tree constructed, the kDNA sequences of the Mexican clones formed two groups including sequences of LCD or LCL clones, apart from the other L. mexicana complex members. These results suggest that the kDNA minicircles of the Mexican isolates are more polymorphic than the kDNA of other members of the L. mexicana complex and have different recognition sites for the restriction enzymes used in this study.
RESUMO
An epidemiological study was carried out in the northern Mexican state, Nayarit. Fourteen patients with possible cutaneous leishmaniasis skin lesions gave positive Montenegro skin tests. Biopsies were taken from the skin ulcer and analyzed by polymerase chain reaction (PCR) with specific primers for the Leishmania mexicana complex; however all biopsies were not amplified. PCR carried out with specific primers for the L. braziliensis complex resulted in the amplification of all patient DNA. DNA from 12 out of 14 biopsies gave positive amplification with primers species specific for L. (Viannia) braziliensis and hybridized with a species specific L. (V.) braziliensis probe. These results demonstrate the presence in Nayarit of at least two members of the L. braziliensis complex. Most of the cutaneous lesions were caused by L. (V.) braziliensis and two by another species belonging to the L. braziliensis complex. As far as we are aware, this is the first report of L. (V.) braziliensis in Nayarit. The main risk factor associated with the contraction of this disease in Nayarit is attributed to working on coffee plantations
Assuntos
Bovinos , Humanos , Animais , Masculino , Feminino , Leishmania braziliensis , Leishmaniose Cutânea/parasitologia , DNA/isolamento & purificação , Leishmaniose Cutânea/epidemiologia , Leishmaniose Cutânea/patologia , México/epidemiologia , Reação em Cadeia da Polimerase , Sensibilidade e Especificidade , Testes CutâneosRESUMO
A 36 year old male was admitted in December 1997 to hospital with afternoon fever, malaise and hepatosplenomegaly. He also had a dry cough, dyspnoea and anaemia. Pneumonia caused by Pneumocystis carinii and human immunodeficiency virus (HIV) infection were documented. The HIV infection was confirmed in 1997 with 290,000 virus copies. The patient had been in the Mexican State of Chiapas which is known to be endemic for visceral leishmaniosis (VL) and localized cutaneous leishmaniosis (LCL). The visceral symptoms were diagnosed as VL and the causal agent was identified as Leishmania (L.) mexicana. Identification of Leishmania was carried out by the analysis of amplified DNA with specific primers belonging to the Leishmania subgenus and by dot blot positive hybridisation of these polymerase chain reaction derived products with kDNA from the L. (L.) mexicana MC strain used as probe. This is the first case in Mexico of VL caused by a species of Leishmania that typically produces a cutaneous disease form.