Highlighting the Unique Roles of Radical S-Adenosylmethionine Enzymes in Methanogenic Archaea.

Radical S-adenosylmethionine (SAM) enzymes catalyze an impressive variety of difficult biochemical reactions in various pathways across all domains of life. These metalloenzymes employ a reduced [4Fe-4S] cluster and SAM to generate a highly reactive 5'-deoxyadenosyl radical that is capable of initiating catalysis on otherwise unreactive substrates. Interestingly, the genomes of methanogenic archaea encode many unique radical SAM enzymes with underexplored or completely unknown functions. These organisms are responsible for the yearly production of nearly 1 billion tons of methane, a potent greenhouse gas as well as a valuable energy source. Thus, understanding the details of methanogenic metabolism and elucidating the functions of essential enzymes in these organisms can provide insights into strategies to decrease greenhouse gas emissions as well as inform advances in bioenergy production processes. This minireview provides an overview of the current state of the field regarding the functions of radical SAM enzymes in methanogens and discusses gaps in knowledge that should be addressed.

Surgical residents' interpretation of diagnostic radiologic imaging in the traumatically injured patient.

BACKGROUND: Senior surgical residents are of paramount importance in directing further therapeutic modalities based on their interpretation of critical diagnostic imaging. We propose that senior surgical residents are proficient with interpreting radiologic imaging studies in the trauma patient. METHODS: A prospective cohort study was performed comparing surgery resident interpretations of computed tomography (CT) scans of the head, maxillofacial bones, spine (cervical, thoracic, lumbar), chest, abdomen, pelvis, and chest X-rays versus final radiologists' reports at a Level II trauma center from September 2014 to May 2015. A Cohen κ coefficient and a statistical analysis of variance testing were used to make multiple comparisons of the data. RESULTS: There were 951 trauma alerts activated in the period stated. Of these, 860 met our age inclusion criteria (age, > 18 years). There were 204 images included with an overall accuracy of 81.3%. Residents were more than 70% successful interpreting seven of nine categories. They achieved an accuracy of 84.6%, 62.5%, and 75% in the cervical, thoracic, and lumbar spine categories, respectively. Forty-one of 50 CT scans of the head were interpreted correctly. Maxillofacial CT scans proved to be the weakest category, with only 50% read accurately. In regard to CT scans of the abdomen and pelvis, 80% proficiency was achieved. Abdominal x-rays were read correctly in all instances and chest x-rays 83.3%. On κ analysis, there was an overall moderate agreement between the two groups with K = 0.449, and an overall p less than 0.0005 (Table 1). A perfect agreement existed with abdominal x-rays. CONCLUSION: Senior surgical residents are capable of interpreting critical images obtained in the trauma setting. When discordance existed with attending radiologists' interpretation, it did not change the clinical outcome or result in any critically missed findings. LEVEL OF EVIDENCE: Therapeutic/Care Management study, Level IV.

Cutaneous Cryptococcoma in a Patient on TNF-α Inhibition.

An 87-year old Caucasian male with past medical history of rheumatoid arthritis (RA) and chronic kidney disease presents with left hand erythema, pain, tenderness, induration and edema. Clinically, these hand findings began proximal to the metacarpo-phalangeal joints and extended to the distal wrist. He was noted to have ipsilateral axillary lymph node enlargement but denied any constitutional signs or symptoms. Laboratory markers of inflammation were poor prognostic indicators due to relatively active RA, the use of chronic daily glucocorticoids and weekly adalimumab use. Oral antibiotics were administered with limited success leading to a skin biopsy which reported a hematogenously disseminated fungal panniculitis; cultures grew Cryptococcus neoformans, however, serum cryptococcal antigen was negative. With initial fluconazole treatment, skin findings and lymphadenopathy improved gradually over the next six months. However, the patient's improvement stagnated and his condition reverted back to the state of initial presentation.