Automated electrotransformation of Escherichia coli on a digital microfluidic platform using bioactivated magnetic beads.

This paper reports on the use of a digital microfluidic platform to perform multiplex automated genetic engineering (MAGE) cycles on droplets containing Escherichia coli cells. Bioactivated magnetic beads were employed for cell binding, washing, and media exchange in the preparation of electrocompetent cells in the electrowetting-on-dieletric (EWoD) platform. On-cartridge electroporation was used to deliver oligonucleotides into the cells. In addition to the optimization of a magnetic bead-based benchtop protocol for generating and transforming electrocompetent E. coli cells, we report on the implementation of this protocol in a fully automated digital microfluidic platform. Bead-based media exchange and electroporation pulse conditions were optimized on benchtop for transformation frequency to provide initial parameters for microfluidic device trials. Benchtop experiments comparing electrotransformation of free and bead-bound cells are presented. Our results suggest that dielectric shielding intrinsic to bead-bound cells significantly reduces electroporation field exposure efficiency. However, high transformation frequency can be maintained in the presence of magnetic beads through the application of more intense electroporation pulses. As a proof of concept, MAGE cycles were successfully performed on a commercial EWoD cartridge using variations of the optimal magnetic bead-based preparation procedure and pulse conditions determined by the benchtop results. Transformation frequencies up to 22% were achieved on benchtop; this frequency was matched within 1% (21%) by MAGE cycles on the microfluidic device. However, typical frequencies on the device remain lower, averaging 9% with a standard deviation of 9%. The presented results demonstrate the potential of digital microfluidics to perform complex and automated genetic engineering protocols.

Ketamine: synaptogenesis, immunomodulation and glycogen synthase kinase-3 as underlying mechanisms of its antidepressant properties.

Major depressive disorder is an extremely debilitating condition affecting millions of people worldwide. Nevertheless, currently available antidepressant medications still have important limitations, such as a low response rate and a time lag for treatment response that represent a significant problem when dealing with individuals who are vulnerable and prone to self-harm. Recent clinical trials have shown that the N-methyl-D-aspartate receptor antagonist, ketamine, can induce an antidepressant response within hours, which lasts up to 2 weeks, and is effective even in treatment-resistant patients. Nonetheless, its use is limited due to its psychotomimetic and addictive properties. Understanding the molecular pathways through which ketamine exerts its antidepressant effects would help in the developing of novel antidepressant agents that do not evoke the same negative side effects of this drug. This review focuses specifically on the effects of ketamine on three molecular mechanisms that are relevant to depression: synaptogenesis, immunomodulation and regulation of glycogen synthase kinase-3 activity.

Glucocorticoids and inflammation: a double-headed sword in depression? How do neuroendocrine and inflammatory pathways interact during stress to contribute to the pathogenesis of depression?

Both glucocorticoids and inflammation have been implicated in the pathogenesis of depression. There is a large body of literature indicating that hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis and glucocorticoid receptor (GR) dysfunction are present in a significant proportion of depressed patients. There is also evidence of increased inflammatory processes in depressed populations, with higher levels of cytokines being a prominent finding - including raised levels of IL-6, and IL-1. These findings appear difficult to reconcile given the well-recognised property of glucocorticoids as prominent anti-inflammatory molecules. There are three potential solutions posed to this dilemma. Firstly, it has been argued that the glucocorticoid system and the inflammatory system exist in balance with one another and chronic stress can disrupt this balance in favour of inflammatory processes at the expense of glucocorticoid signalling. It has also been suggested that glucocorticoids have more complex actions than typically thought, and, in low levels can actually be pro-inflammatory, rather than universally anti-inflammatory. Lastly, it is possible that inflammation and glucocorticoid signalling may act on the same processes and structures without direct interaction to give rise to cumulative damage. Improved understanding of this interaction will allow further progress in determining targets for treatment.

Reoperative pulmonary metastasectomy for sarcomatous pediatric histologies.

BACKGROUND: The role for reoperative pulmonary metastasectomy in patients with "pediatric sarcomas" (osteosarcoma, nonrhabdomyosarcoma-soft tissue sarcoma, and Ewing's sarcoma) is undefined. METHODS: We reviewed our results for patients with these histologic presentations (median age, 17.5 years; range, 6 to 32 years) having two (70), three (27), or four (10) metastasectomies between January 1965 and March 1995 to define postresection survival and potential prognostic factors. Simple wedges (88 thoracotomies, 84%) were performed more frequently than anatomic (17 thoracotomies, 16%) resections. RESULTS: With a median potential follow-up of 12.7 years, median survival was 2.25, 3.60, and 0.96 years from the second, third, and fourth explorations, respectively. Primary tumor site, sex, histology, age, maximal metastasis size, and systemic chemotherapy did not influence survival. Resectability was the most important prognostic factor (5.6 versus 0.7 years, 5.2 versus 2.5 years, 2.2 versus 0.2 years, resectable versus unresectable, median survival from second, third, and fourth thoracotomy, respectively). Unresectability, disease-free interval less than 6 months between initial (ie, first) pulmonary resection and the second thoracotomy, and two or more preoperative nodules noted on the right were simultaneously negatively associated with survival from the second thoracotomy. Unresectability or finding two or more metastases negatively affected survival from the third thoracotomy. CONCLUSIONS: These data imply that repeat metastasectomy can salvage a subset of patients with sarcomatous pediatric histologic presentations who retain favorable prognostic determinants.

Acrocallosal syndrome: additional manifestations.

The acrocallosal syndrome (ACS) is a probable autosomal recessive condition of macrocephaly, craniofacial and hand and foot abnormalities, absence of the corpus callosum, and mental retardation. This patient had characteristics of the ACS but also had a severe congenital heart defect and other visceral malformations. After comparing the ACS with and contrasting it to other disorders, we concluded that the internal organ abnormalities found in this patient probably represent further manifestations of the ACS.

Ceftazidime concentrations in human aqueous humor.

Two grams of ceftazidime was given to 25 patients before cataract surgery. Mean aqueous humor concentrations of 2.8, 3.2, 3.39, and 1.94 micrograms/mL were observed 30 minutes and 1, 2, 4, and 6 hours, respectively, after administration of the drug. These concentrations are many times higher than the minimum inhibitory concentration (MIC) of ceftazidime against 90% ( MIC90 ) of isolates of Escherichia coli, Klebsiella sp, Proteus mirabilis, and indole-positive Proteus sp. The peak aqueous humor level was also equivalent to or slightly higher than the MIC90 for Pseudomonas aeruginosa.