Human apolipoprotein E, a blood plasma protein, mediates the transport and uptake of cholesterol and lipid by way of its high affinity interaction with different cellular receptors, including the low-density lipoprotein (LDL) receptor. The three-dimensional structure of the LDL receptor-binding domain of apoE has been determined at 2.5 angstrom resolution by x-ray crystallography. The protein forms an unusually elongated (65 angstroms) four-helix bundle, with the helices apparently stabilized by a tightly packed hydrophobic core that includes leucine zipper-type interactions and by numerous salt bridges on the mostly charged surface. Basic amino acids important for LDL receptor binding are clustered into a surface patch on one long helix. This structure provides the basis for understanding the behavior of naturally occurring mutants that can lead to atherosclerosis.

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Antibiotic therapy is suggested for patients who have symptoms of sepsis, or for patients in whom specific organisms are identified from cultures obtained during surgery. The transsphenoidal approach is recommended over open craniotomy for surgical drainage.

Untreated Cushing's disease and the resultant chronically elevated glucocorticoid levels lead to severe metabolic disturbances, including diabetes mellitus, obesity, hypertension, muscle wasting, and osteoporosis. Although transsphenoidal resection has become the standard of care for Cushing's disease with high initial success rates, little information is available on the long-term morbidity and mortality of patients in remission compared with patients with recurrent or persistent Cushing's disease after such treatment. We therefore conducted a retrospective study of 289 patients with Cushing's disease who underwent transsphenoidal microsurgery for an ACTH-secreting adenoma at a tertiary care center exclusively by one surgeon (C.B.W.). Postoperative remission was achieved in 82% (n = 236) of patients, with best initial remission rates observed in patients with grade I (86%) and II (83%) or stage 0 (88%), A (94%), and B (100%) tumors. Male gender, larger tumor size, and higher stage predicted poorer initial outcome. Long-term follow-up was obtained on 178 patients, with a median follow-up time of 11.1 yr (range, 0.6-24.1 yr). Thirteen of 150 (9%) of patients in initial remission developed recurrent disease, and 12 patients underwent additional treatment. At last follow-up, only two of these patients had active disease. However, of the 28 patients with initial persistent disease who had follow-up greater than 6 months, 10 patients continued to have active disease at last follow-up. Although overall survival rates in patients with initial remission did not differ significantly from expected compared with the general population based on age and sex distribution, patients with initial persistent disease had a significant increase in mortality compared with the expected mortality. Thus, successful treatment of Cushing's disease is associated with normal long-term survival. These results suggest that patients with persistent Cushing's disease require early and aggressive intervention to attempt to prevent this excess mortality.

The likelihood of rupture of unruptured intracranial aneurysms that were less than 10 mm in diameter was exceedingly low among patients in group 1 and was substantially higher among those in group 2. The risk of morbidity and mortality related to surgery greatly exceeded the 7.5-year risk of rupture among patients in group 1 with unruptured intracranial aneurysms smaller than 10 mm in diameter.

The biological function of specific gene products often is determined experimentally by blocking their expression in an organism and observing the resulting phenotype. Chromophore-assisted laser inactivation using malachite green (MG)-tagged antibodies makes it possible to inactivate target proteins in a highly restricted manner, probing their temporally and spatially resolved functions. In this report, we describe the isolation and in vitro characterization of a MG-binding RNA motif that may enable the same high-resolution analysis of gene function specifically at the RNA level (RNA-chromophore-assisted laser inactivation). A well-defined asymmetric internal bulge within an RNA duplex allows high affinity and high specificity binding by MG. Laser irradiation in the presence of low concentrations of MG induces destruction of the MG-binding RNA but not of coincubated control RNA. Laser-induced hydrolysis of the MG-binding RNA is restricted predominantly to a single nucleotide within the bulge. By appropriately incorporating this motif into a target gene, transcripts generated by the gene may be effectively tagged for laser-mediated destruction.

We find that conjugation and chemical composition can alter fundamental aspects of aptamer residence in circulation and distribution to tissues. Though the primary effect of PEGylation was on aptamer clearance, the prolonged systemic exposure afforded by presence of the 20 kDa moiety appeared to facilitate distribution of aptamer to tissues, particularly those of highly perfused organs.

Aptamers (protein binding oligonucleotides) have potential as a new class of targeted therapeutics. For applications requiring chronic systemic administration, aptamers must achieve high-affinity target binding while simultaneously retaining high in vivo stability, tolerability, and ease of chemical synthesis. To this end, we describe a method for generating aptamers composed entirely of 2'-O-methyl nucleotides (mRmY). We present conditions under which 2'-O-methyl transcripts can be generated directly and use these conditions to select a fully 2'-O-methyl aptamer from a library of 3 x 10(15) unique 2'-O-methyl transcripts. This aptamer, ARC245, is 23 nucleotides in length, binds to vascular endothelial growth factor (VEGF) with a Kd of 2 nM, and inhibits VEGF activity in cellular assays. Notably, ARC245 is so stable that degradation cannot be detected after 96 hr in plasma at 37 degrees C or after autoclaving at 125 degrees C. We believe ARC245 has considerable potential as an antiangiogenesis therapeutic.