The Effect of Heavy Metals on Conjugation Efficiency of an F-Plasmid in Escherichia coli.

Conjugation, the process by which conjugative plasmids are transferred between bacteria, is regarded as a major contributor to the spread of antibiotic resistance, in both environmental and clinical settings. Heavy metals are known to co-select for antibiotic resistance, but the impact of the presence of these metals on conjugation itself is not clear. Here, we systematically investigate the impact that five heavy metals (arsenic, cadmium, copper, manganese, and zinc) have on the transfer of an IncF conjugative plasmid in Escherichia coli. Our results show that two of the metals, cadmium and manganese, have no significant impact, while arsenic and zinc both reduce conjugation efficiency by approximately 2-fold. Copper showed the largest impact, with an almost 100-fold decrease in conjugation efficiency. This was not mediated by any change in transcription from the major Py promoter responsible for transcription of the conjugation machinery genes. Further, we show that in order to have this severe impact on the transfer of the plasmid, copper sulfate needs to be present during the mating process, and we suggest explanations for this.

Desmoplastic nevus: An entity distinct from spitz nevus and blue nevus.

Desmoplastic (sclerotic) nevus is an infrequently reported poorly characterized benign melanocytic proliferation, with only 4 case series published to date. To better define this nevus, we examined the clinical and histologic features of 25 lesions. Desmoplastic nevus is seen in both children and adults and can be located on the face, trunk, or extremities. There is a female predominance. Clinically, it can resemble intradermal nevus, atypical nevus, melanoma, and pigmented basal cell carcinoma. These are generally small, symmetric, and well-circumscribed lesions, averaging 3.5 mm in diameter. The most distinctive features include predominantly compound growth, a zonal configuration with greater cellularity in the superficial portion of the lesion, and a mixture of melanocytic phenotypes including type A, B, and C nevus cells, ovoid and dendritic melanocytes, and Spitzoid melanocytes. A distinctive eosinophilic stroma which either resembles that of a dermatofibroma or neurofibroma is always present. Variable amounts of melanin pigment are found in both tumor cells and macrophages, but this is not a prominent feature. Mitotic activity is exceedingly rare (1 case), and pleomorphism is minimal. These lesions are distinct from typical compound nevus, Spitz nevus, epithelioid blue nevus, and desmoplastic melanoma, to which they are often compared. Strict application of these histologic features allows definitive diagnosis of desmoplastic nevus as a distinct form of a benign melanocytic nevus.

Experience on how to implement a preanalytical and POCT unit in Madrid's IFEMA field hospital during this unprecedented COVID-19 emergency.

To fight the virus SARS-CoV-2 spread to Europe from China and to give support to the collapsed public health system, the Spanish Health Authorities developed a field hospital located in the facilities of Madrid exhibition centre (IFEMA) to admit and treat patients diagnosed with SARS-CoV-2 infectious disease (COVID-19). The Department of Laboratory Medicine of La Paz University Hospital in Madrid (LMD-HULP) was designated to provide laboratory services. Due to the emergency, the IFEMA field hospital had to be prepared for patient admission in less than 1 week and the laboratory professionals had to collaborate in a multidisciplinary group to assure that resources were available to start on time. The LMD-HULP participated together with the managers in the design of the tests portfolio and the integration of the healthcare information systems (IS) (hospital IS, laboratory IS and POCT management system). Laboratorians developed a strategy to quickly train clinicians and nurses on test requests, sample collection procedures and management/handling of the POCT blood gas analyser both by written materials and training videos. The IFEMA´s preanalytical unit managed 3782 requests, and more than 11,000 samples from March 27th to April 30th. Furthermore, 1151 samples were measured by blood gas analysers. In conclusion, laboratory professionals must be resilient and have to respond timely in emergencies as this pandemic. The lab's personnel selection, design and monitoring indicators to maintain and further improve the quality and value of laboratory services is crucial to support medical decision making and provide better patient care.

Pathology review of thin melanoma and melanoma in situ in a multidisciplinary melanoma clinic: impact on treatment decisions.

PURPOSE: Patients with thin melanoma (