Prolonged hypothermia for neurological protection

Treatment with mild hypothermia induced after cardiopulmonary resuscitation has become a standard of care, but optimal timing and duration of hypothermia remains unclear. We present a 66-year-old man admitted after an out-of-hospital cardiac arrest. Because of his severe hypoxemia, cardiopulmonary instability, and respiratory acidosis after resuscitation, he was continued on therapeutic hypothermia until his hypoxia resolved. As a result, the patient was kept at the goal hypothermic temperature of 33°C for a total of 48 hours, compared with the usual 24-hour standard, with excellent sustained neurological recovery. This case documents the usefulness of extending hypothermia when applied to severely unstable patients and suggests that a sliding-target approach may be applied on a patient-by-patient basis.

Use of combinatorial genetic libraries to humanize N-linked glycosylation in the yeast Pichia pastoris

The secretory pathway of Pichia pastoris was genetically re-engineered to perform sequential glycosylation reactions that mimic early processing of N-glycans in humans and other higher mammals. After eliminating nonhuman glycosylation by deleting the initiating alpha-1,6-mannosyltransferase gene from P. pastoris, several combinatorial genetic libraries were constructed to localize active alpha-1,2-mannosidase and human beta-1,2-N-acetylglucosaminyltransferase I (GnTI) in the secretory pathway. First, >32 N-terminal leader sequences of fungal type II membrane proteins were cloned to generate a leader library. Two additional libraries encoding catalytic domains of alpha-1,2-mannosidases and GnTI from mammals, insects, amphibians, worms, and fungi were cloned to generate catalytic domain libraries. In-frame fusions of the respective leader and catalytic domain libraries resulted in several hundred chimeric fusions of fungal targeting domains and catalytic domains. Although the majority of strains transformed with the mannosidase/leader library displayed only modest in vivo [i.e., low levels of mannose (Man)(5)-(GlcNAc)(2)] activity, we were able to isolate several yeast strains that produce almost homogeneous N-glycans of the (Man)(5)-(GlcNAc)(2) type. Transformation of these strains with a UDP-GlcNAc transporter and screening of a GnTI leader fusion library allowed for the isolation of strains that produce GlcNAc-(Man)(5)-(GlcNAc)(2) in high yield. Recombinant expression of a human reporter protein in these engineered strains led to the formation of a glycoprotein with GlcNAc-(Man)(5)-(GlcNAc)(2) as the primary N-glycan. Here we report a yeast able to synthesize hybrid glycans in high yield and open the door for engineering yeast to perform complex human-like glycosylation.