Protocolized Laboratory Screening for the Medical Clearance of Psychiatric Patients in the Emergency Department: A Systematic Review.

OBJECTIVE: Emergency department (ED) patients with psychiatric chief complaints undergo medical screening to rule out underlying or comorbid medical illnesses prior to transfer to a psychiatric facility. This systematic review attempts to determine the clinical utility of protocolized laboratory screening for the streamlined medical clearance of ED psychiatric patients by determining the clinical significance of individual laboratory results. METHODS: We searched PubMed, Embase, and Scopus using the search terms "emergency department, psychiatry, diagnostic tests, laboratories, studies, testing, screening, and clearance" up to June 2017 for studies on adult psychiatric patients. This systematic review follows the recommendations of Meta-analysis of Observational Studies in Epidemiology (MOOSE) statement. The quality of each study was rated according to the Newcastle-Ottawa quality assessment scale. RESULTS: Four independent reviewers identified 2,847 publications. We extracted data from three studies (n = 629 patients). Included studies defined an abnormal test result as any laboratory result that falls out of the normal range. A laboratory test result was deemed as "clinically significant" only when patient disposition or treatment plan was changed because of that test result. Across the three studies the prevalence of clinically significant results were low (0.0%-0.4%). CONCLUSIONS: The prevalence of clinically significant laboratory test results were low, suggesting that according to the available literature, routine laboratory testing does not significantly change patient disposition. Due to the paucity of available research on this subject, we could not determine the clinical utility of protocolized laboratory screening tests for medical clearance of psychiatric patients in the ED. Future research on the utility of routine laboratory testing is important in a move toward shared decision making and patient-centered health care.

Escherichia coli L-serine deaminase requires a [4Fe-4S] cluster in catalysis.

L-Serine deaminases catalyze the deamination of L-serine, producing pyruvate and ammonia. Two families of these proteins have been described and are delineated by the cofactor that each employs in catalysis. These are the pyridoxal 5'-phosphate-dependent deaminases and the deaminases that are activated in vitro by iron and dithiothreitol. In contrast to the enzymes that employ pyridoxal 5'-phosphate, detailed physical and mechanistic characterization of the iron-dependent deaminases is limited, primarily because of their extreme instability. We report here the characterization of L-serine deaminase from Escherichia coli, which is the product of the sdaA gene. When purified anaerobically, the isolated protein contains 1.86 +/- 0.46 eq of iron and 0.670 +/- 0.019 eq of sulfide per polypeptide and displays a UV-visible spectrum that is consistent with a [4Fe-4S] cluster. Reconstitution of the protein with iron and sulfide generates considerably more of the cluster, and treatment of the reconstituted protein with dithionite gives rise to an axial EPR spectrum, displaying g axially = 2.03 and g radially = 1.93. Mössbauer spectra of the (57)Fe-reconstituted protein reveal that the majority of the iron is in the form of [4Fe-4S](2+) clusters, as evidenced by the typical Mössbauer parameters-isomer shift, delta = 0.47 mm/s, quadrupole splitting of Delta E(Q) = 1.14 mm/s, and a diamagnetic (S = 0) ground state. Treatment of the dithionite-reduced protein with L-serine results in a slight broadening of the feature at g = 2.03 in the EPR spectrum of the protein, and a dramatic loss in signal intensity, suggesting that the amino acid interacts directly with the cluster.