Cryptic environmental conjugative plasmid recruits a novel hybrid transposon resulting in a new plasmid with higher dispersion potential.

Cryptic conjugative plasmids lack antibiotic-resistance genes (ARGs). These plasmids can capture ARGs from the vast pool of the environmental metagenome, but the mechanism to recruit ARGs remains to be elucidated. To investigate the recruitment of ARGs by a cryptic plasmid, we sequenced and conducted mating experiments with Escherichia coli SW4848 (collected from a lake) that has a cryptic IncX (IncX4) plasmid and an IncF (IncFII/IncFIIB) plasmid with five genes that confer resistance to aminoglycosides (strA and strB), sulfonamides (sul2), tetracycline [tet(A)], and trimethoprim (dfrA5). In a conjugation experiment, a novel hybrid Tn21/Tn1721 transposon of 22,570 bp (designated Tn7714) carrying the five ARG mobilized spontaneously from the IncF plasmid to the cryptic IncX plasmid. The IncF plasmid was found to be conjugative when it was electroporated into E. coli DH10B (without the IncX plasmid). Two parallel conjugations with the IncF and the new IncX (carrying the novel Tn7714 transposon) plasmids in two separate E. coli DH10B as donors and E. coli J53 as the recipient revealed that the conjugation rate of the new IncX plasmid (with the novel Tn7714 transposon and five ARGs) is more than two orders of magnitude larger than the IncF plasmid. For the first time, this study shows experimental evidence that cryptic environmental plasmids can capture and transfer transposons with ARGs to other bacteria, creating novel multidrug-resistant conjugative plasmids with higher dispersion potential. IMPORTANCE: Cryptic conjugative plasmids are extrachromosomal DNA molecules without antibiotic-resistance genes (ARGs). Environmental bacteria carrying cryptic plasmids with a high conjugation rate threaten public health because they can capture clinically relevant ARGs and rapidly spread them to pathogenic bacteria. However, the mechanism to recruit ARG by cryptic conjugative plasmids in environmental bacteria has not been observed experimentally. Here, we document the first translocation of a transposon with multiple clinically relevant ARGs to a cryptic environmental conjugative plasmid. The new multidrug-resistant conjugative plasmid has a conjugation rate that is two orders of magnitude higher than the original plasmid that carries the ARG (i.e., the new plasmid from the environment can spread ARG more than two orders of magnitude faster). Our work illustrates the importance of studying the mobilization of ARGs in environmental bacteria. It sheds light on how cryptic conjugative plasmids recruit ARGs, a phenomenon at the root of the antibiotic crisis.

Nanoscale Characterization of Photocurrent and Photovoltage in Polycrystalline Solar Cells.

We investigate the role of grain structures in nanoscale carrier dynamics of polycrystalline solar cells. By using Kelvin probe force microscopy (KPFM) and near-field scanning photocurrent microscopy (NSPM) techniques, we characterize nanoscopic photovoltage and photocurrent patterns of inorganic CdTe and organic-inorganic hybrid perovskite solar cells. For CdTe solar cells, we analyze the nanoscale electric power patterns that are created by correlating nanoscale photovoltage and photocurrent maps on the same location. Distinct relations between the sample preparation conditions and the nanoscale photovoltaic properties of microscopic CdTe grain structures are observed. The same techniques are applied for characterization of a perovskite solar cell. It is found that a moderate amount of PbI2 near grain boundaries leads to the enhanced photogenerated carrier collections at grain boundaries. Finally, the capabilities and the limitations of the nanoscale techniques are discussed.

Manejo anestésico de pacientes embarazada con síndrome de Osler-Weber-Rendú e insuficiencia cardiaca congestiva / Anesthetic management of pregnant patient with osler weber-rendu syndrome and congestive heart failure

Paciente femenina de 20 años de edad con síndrome de Osler-Weber-Rendú (telangiectasia hemorrágica hereditaria) en trabajo de parto. Se presenta el manejo anestésico y preparación preoperatoria y se discuten los problemas específicos de este síndrome asociado al embarazo

Ultrasonido en las masas cervicales altas / Ultrasound in high cervical masses

La localización superficial de las masas en la región cervical alta las hace con facilidad accesibles a la exploración mediante equipos de ultrasonido. Con ello podemos caracterizar la textura de la masa. Conocer sus dimensiones e inclusive guiar la punción biopsia para estudio histopatológico. Los patrones ecográficos resultan bastante confiables para sospechar el diagnóstico. Así las masas benignas se comportan como lesiones quísticas, de bordes nítidos, con algunos ecos finos internos de acuerdo al tipo específico de tumor. Las masas malignas son lesiones ecogénicas, con ecos irregulares en su interior y márgenes difusos. Se menciona la experiencia con 35 enfermos, entre los culaes se incluyen glándulas salivales, ganglios cervicales, quistes tiroglosos y una tumoración irregular, probable histiocitoma o neurofibroma.

Embarazo combinado: intrauterino y ectópico; presentación de un caso clínico y actualización de criterios diagnósticos / Combined pregnancy: intrauterine and ectopic; report of a clinical case and current diagnostic criteria

Los autores informan sobre el caso clínico de una paciente que presentó embarazo combinado intrauterino ectópico, complicado con amenaza de aborto, que culminó con la expulsión espontánea del producto intrauterino. Había además un quiste de retención 4 cm en el anexo contrario al ectópico dificultando la exploración ecográfica. Se analizan los criterios diagnósticos actuales para la evaluación del embarazo intrauterino temprano y se resalta la importancia de la detección precoz de cambios sonográficos y biológicos que permitan reconocer un embarazo temprano anormal antes de que aparezcan las complicaciones