👤 Mark J Eisenberg

Cholesteryl ester transfer protein (CETP) inhibitors increase serum high-density lipoprotein cholesterol (HDL-c) concentration; however, their impact on cardiovascular outcomes is not clear. This systematic review examines the effect of CETP inhibitors on serum lipid profiles, cardiovascular events, and all-cause mortality. We searched MEDLINE, Embase, and the Cochrane Library of Clinical Trials for placebo-controlled randomized controlled trials (RCTs) that examined the effect of a CETP inhibitor (dalcetrapib, anacetrapib, evacetrapib, or TA-8995) on all-cause mortality, major adverse cardiovascular events (MACE), or the components of MACE at ≥6 months. Data were pooled using random-effects models. A total of 11 RCTs (n = 62,431) were included in our systematic review; 4 examined dalcetrapib (n = 16,612), 6 anacetrapib (n = 33,682), and 1 evacetrapib (n = 12,092). Compared to dalcetrapib, ana-cetrapib and evacetrapib were more efficacious at raising HDL-c levels (∼100-130 vs. ∼30%). Anacetrapib and evacetrapib also decreased low-density lipoprotein cholesterol (LDL-c) by approximately 30% while dalcetrapib did not affect the LDL-c level. Overall, CETP inhibitors were not associated with the incidence of MACE (pooled relative risk [RR]: 0.97; 95% confidence interval [CI]: 0.91-1.04). CETP inhibitors may decrease the risks of nonfatal myocardial infarction (MI) (RR: 0.93; 95% CI: 0.87-1.00) and cardiovascular death (RR: 0.92; 95% CI: 0.83-1.01), though these trends did not reach statistical significance. CETP inhibitors are not associated with an increased risk of MACE or all-cause mortality. There is a trend towards small reductions in nonfatal MI and cardiovascular death, though the clinical im-portance of such reductions is likely modest. Show less

Y chromosome short tandem repeat (Y-STR) loci are important genetic markers for forensic biological evidence analyses. However, paternal inheritance, reduced effective population size, and lack of independence between loci can reduce Y-STR diversity and may yield greater population substructure effects on a locus-by-locus basis compared with the autosomal STR loci. Population studies are necessary to assess the genetic variation of forensically relevant markers so that proper inferences can be made about the rarity of DNA profiles. This study examined 16 Y-STRs in three sampled populations of Native Americans from Alaska: Inupiat, Yupik, and Athabaskan. Population genetic and statistical issues addressed were: (1) the degree of diversity at locus and haplotype levels, (2) determination of the loci that contribute more so to haplotype diversity, and (3) the effects of population substructure on forensic statistical calculations of the rarity of a Y-STR profile. All three population samples were highly polymorphic at the haplotype level for the 16 Y-STR markers; however, the Native Americans demonstrated reduced genetic diversity compared with major US populations. The degree of substructure indicated that the three populations were related and admixed in terms of paternal lineage. The examination of more polymorphic loci may be needed to increase the power of discrimination of Y-STR systems in these populations. Show less

We have analyzed structure-sequence relationships in 32 families of flavin adenine dinucleotide (FAD)-binding proteins, to prepare for genomic-scale analyses of this family. Four different FAD-family folds were identified, each containing at least two or more protein families. Three of these families, exemplified by glutathione reductase (GR), ferredoxin reductase (FR), and p-cresol methylhydroxylase (PCMH) were previously defined, and a family represented by pyruvate oxidase (PO) is newly defined. For each of the families, several conserved sequence motifs have been characterized. Several newly recognized sequence motifs are reported here for the PO, GR, and PCMH families. Each FAD fold can be uniquely identified by the presence of distinctive conserved sequence motifs. We also analyzed cofactor properties, some of which are conserved within a family fold while others display variability. Among the conserved properties is cofactor directionality: in some FAD-structural families, the adenine ring of the FAD points toward the FAD-binding domain, whereas in others the isoalloxazine ring points toward this domain. In contrast, the FAD conformation and orientation are conserved in some families while in others it displays some variability. Nevertheless, there are clear correlations among the FAD-family fold, the shape of the pocket, and the FAD conformation. Our general findings are as follows: (a) no single protein 'pharmacophore' exists for binding FAD; (b) in every FAD-binding family, the pyrophosphate moiety binds to the most strongly conserved sequence motif, suggesting that pyrophosphate binding is a significant component of molecular recognition; and (c) sequence motifs can identify proteins that bind phosphate-containing ligands. Show less

d-Lactate dehydrogenase (d-LDH) of Escherichia coli is a peripheral membrane respiratory enzyme involved in electron transfer, located on the cytoplasmic side of the inner membrane. d-LDH catalyzes the oxidation of d-lactate to pyruvate, which is coupled to transmembrane transport of amino acids and sugars. Here we describe the crystal structure at 1.9 A resolution of the three domains of d-LDH: the flavin adenine dinucleotide (FAD)-binding domain, the cap domain, and the membrane-binding domain. The FAD-binding domain contains the site of d-lactate reduction by a noncovalently bound FAD cofactor and has an overall fold similar to other members of a recently discovered FAD-containing family of proteins. This structural similarity extends to the cap domain as well. The most prominent difference between d-LDH and the other members of the FAD-containing family is the membrane-binding domain, which is either absent in some of these proteins or differs significantly. The d-LDH membrane-binding domain presents an electropositive surface with six Arg and five Lys residues, which presumably interacts with the negatively charged phospholipid head groups of the membrane. Thus, d-LDH appears to bind the membrane through electrostatic rather than hydrophobic forces. Show less

Extreme halophilic archaea are saturated with salt and the intracellular electrolyte concentration exceeds that of the extracellular environment. Enzymes and other proteins from extreme halophilic archaea have been purified for many years and studied by biochemical and biophysical solution methodologies. They are active and stable at multimolar salt concentrations and denature below 2 to 3 M NaCl or KCl. Adaptation to these high concentrations of salt, genetic and evolutionary aspects, and the possibility of biotechnological applications are problems of considerable interest. Since the status of this fascinating field of research was reviewed in 1992, malate dehydrogenase from Haloarcula marismortui, now known to be a tetramer, was sequenced, its gene was cloned and expressed in active form, and its physical properties were redefined. A single mutation of Arg100 (in the enzyme active site) to Gln switched the enzyme specificity from malate to lactate dehydrogenase. Recent determination of its molecular structure by X-ray crystallography (O. Dym et al., in press) provides an exciting basis for the understanding of the structure and function of extreme halophilic enzymes. A major problem which so far has not been tackled in the study of extreme halophilic archaea is the understanding of protein nucleic acid interactions which are essential for the performance of biological function. Whereas the stability and activity of enzymes and other proteins can be modified to perform at high salt concentrations by use of currently known structural concepts, the existence of meaningful protein nucleic acid interactions in physiological concentrations of 4 to 5 M KCl constitutes an unsolved enigma worth intensive investigation. Show less

Halophilic malate dehydrogenase (hMDH) from Haloarcula marismortui has been isolated, purified and characterized by biochemical and biophysical solution studies. A stabilization mechanism at extremely high concentrations of salt, based on the formation of co-operative hydrate bonds between the protein and hydrated salt ions, was suggested from thermodynamic analysis of native enzyme solutions. Recently the gene coding for hMDH was isolated and sequenced and an active enzyme cloned (F. Cendrin, J. Chroboczek, G. Zaccai, H. Eisenberg and M. Mevarech, unpublished work). A study of the crystal structure of hMDH in a high-salt physiological medium is in progress (O. Butbul-Dym & J. Sussman, personal communication). Here we discuss in depth implications of these recent developments on our earlier results. Show less