Integrated control of Boophilus microplus ticks in Cuba based on vaccination with the anti-tick vaccine Gavac TM

Boophilus microplus has developed resistance against a range of chemical acaricides which has stimulated the development of alternative methods such as vaccination against ticks. In Cuba, the Bm86-based recombinant vaccine Gavac^TM has been successfully used in a number of controlled laboratory and field trials in cattle against B. microplus. In this paper, we have evaluated Gavac^TM in a large scale field trial wherein 588,573 dairy cattle were vaccinated with the aim to reduce the number of acaricidal treatments. It was found that the number of acaricidal treatments could be reduced by 87% over a period of 8 years (1995–2003). Prior to the introduction of the vaccine, 54 clinical cases of babesiosis and six fatal cases were reported per 1000 animals. Six years later, the incidence of babesiosis was reduced to 1.9 cases per 1000 cattle and mortality reduced to 0.18 per 1000. The national consumption of acaricides in Cuba could be reduced by 82% after the implementation of the integrated anti-B. microplus control program.     

Aminoimidazo[1,2-a]pyridines as a new structural class of cyclin-dependent kinase inhibitors. Part 1: Design, synthesis, and biological evaluation

We have identified a novel structural class of protein serine/threonine kinase inhibitors comprised of an aminoimidazo[1,2-a]pyridine nucleus. Compounds from this family are shown to potently inhibit cyclin-dependent kinases by competing with ATP for binding to a catalytic subunit of the protein. Structure-based design approach was used to direct this chemical scaffold toward generating potent and selective CDK2 inhibitors. The discovery of this new class of ATP-site directed protein kinase inhibitors, aminoimidazo[1,2-a]pyridines, provides the basis of new medicinal chemistry tool in search for an effective treatment of cancer and other diseases that involve protein kinase signaling pathways.     

Inhibitors of hepatitis C virus NS3.4A protease 2. Warhead SAR and optimization

The alpha-ketoamide warhead (e.g., 15) was found to be a practical replacement for aliphatic aldehydes in a series of HCV NS3.4A protease inhibitors. Structure-activity relationships and prime side optimization are discussed.     

Exchange of DNA base pairs that coincides with recognition of homology promoted by E. coli RecA protein

The unresolved mechanism by which a single strand of DNA recognizes homology in duplex DNA is central to understanding genetic recombination and repair of double-strand breaks. Using stopped-flow fluorescence we monitored strand exchange catalyzed by E. coli RecA protein, measuring simultaneously the rate of exchange of A:T base pairs and the rates of formation and dissociation of the three-stranded intermediates called synaptic complexes. The rate of exchange of A:T base pairs was indistinguishable from the rate of formation of synaptic complexes, whereas the rate of displacement of a single strand from complexes was five to ten times slower. This physical evidence shows that a subset of bases exchanges at a rate that is fast enough to account for recognition of homology. Together, several studies suggest that a mechanism governed by the dynamic structure of DNA and catalyzed by diverse enzymes underlies both recognition of homology and initiation of strand exchange.     

Continued proteomic analysis of Mycobacterium leprae subcellular fractions

Recently the sequence of the Mycobacterium leprae chromosome, the only known obligate intracellular mycobacterium, was completed. It has a dramatic reduction in functional genes, with a coding capacity of only 49.5%, the lowest one so far observed among bacterial genomes. The leprosy bacillus seems to preserve a minimal set of genes that allows its survival in the host. The identification of genes that are actually expressed by the bacterium is of high significance in the context of mycobacterial pathogenesis. In this current study, a proteomic approach was undertaken to identify the proteins present in the soluble/cytosol and membrane subcellular fractions obtained from armadillo derived M. leprae. Proteins from each fraction were separated by two-dimensional gel electrophoresis (2-DE) and identified by mass spectrometry. A total of 147 protein spots were identified from 2-DE patterns and shown to comprise products of 44 different genes, twenty eight of them corresponding to new proteins. Additionally, two highly basic proteins (with pI >10.0) were isolated by heparin affinity chromatography and identified by N-terminal sequencing. This study constitutes the first application of proteomics to a host-derived Mycobacterium.     

Proteome analysis of human colon cancer by two-dimensional difference gel electrophoresis and mass spectrometry

Two-dimensional difference gel electrophoresis (2-D DIGE) coupled with mass spectrometry (MS) was used to investigate tumor-specific changes in the proteome of human colorectal cancers and adjacent normal mucosa. For each of six patients with different stages of colon cancer, Cy5-labeled proteins isolated from tumor tissue were combined with Cy3-labeled proteins isolated from neighboring normal mucosa and separated on the same 2-D gel along with a Cy2-labeled mixture of all 12 normal/tumor samples as an internal standard. Over 1500 protein spot-features were analyzed in each paired normal/tumor comparison, and using DIGE technology with the mixed-sample internal standard, statistically significant quantitative comparisons of each protein abundance change could be made across multiple samples simultaneously without interference due to gel-to-gel variation. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) and tandem (TOF/TOF) MS provided sensitive and accurate mass spectral data for database interrogation, resulting in the identification of 52 unique proteins (including redundancies due to proteolysis and post-translationally modified isoforms) that were changing in abundance across the cohort. Without the benefit of the Cy2-labeled 12 sample mixture internal standard, 42 of these proteins would have been overlooked due to the large degree of variation inherent between normal and tumor samples.     

Stability of enzymes and proteins in dried glassy systems: effect of simulated sunlight conditions

The purpose of the present work was to study the effects of simulated sunlight conditions on enzyme inactivation and structural damage in dehydrated glassy systems. Freeze-dried samples containing different enzymes (lactase, invertase, lysozyme and amyloglucosidase) were exposed to light using a medium-pressure metal halide HPA 400 W lamp. After 1 h of light exposure, the samples showed a significant reduction (more than 50%) in the denaturation peak area as analyzed by DSC, and this could be attributed to protein denaturation. For most of the pure enzymes, the loss of enzymic activity after 1 h of light exposure was around 50%. In the case of enzymes included in anhydrous model systems (trehalose, raffinose, maltodextrin, and dextran), the remaining activity also decreased dramatically during the light treatment. We showed that the light exposure in dehydrated systems generated both the loss of enzymic activity and structural changes such as denaturation (observed by DSC) and protein fragmentation and aggregation (observed by electrophoresis). Overall, we can conclude that a short exposure to the light produces dramatic changes in the enzymic activity in dehydrated systems with or without protective matrices.     

Structure of the Q237W mutant of HhaI DNA methyltransferase: an insight into protein-protein interactions

We have determined the structure of a mutant (Q237W) of HhaI DNA methyltransferase, complexed with the methyl-donor product AdoHcy. The Q237W mutant proteins were crystallized in the monoclinic space group C2 with two molecules in the crystallographic asymmetric unit. Protein-protein interface calculations in the crystal lattices suggest that the dimer interface has the specific characteristics for homodimer protein-protein interactions, while the two active sites are spatially independent on the outer surface of the dimer. The solution behavior suggests the formation of HhaI dimers as well. The same HhaI dimer interface is also observed in the previously characterized binary (M.HhaI-AdoMet) and ternary (M.HhaI-DNA-AdoHcy) complex structures, crystallized in different space groups. The dimer is characterized either by a non-crystallographic two-fold symmetry or a crystallographic symmetry. The dimer interface involves three segments: the amino-terminal residues 2-8, the carboxy-terminal residues 313-327, and the linker (amino acids 179-184) between the two functional domains--the catalytic methylation domain and the DNA target recognition domain. Both the amino- and carboxy-terminal segments are part of the methylation domain. We also examined protein-protein interactions of other structurally characterized DNA MTases, which are often found as a 2-fold related 'dimer' with the largest dimer interface area for the group-beta MTases. A possible evolutionary link between the Type I and Type II restriction-modification systems is discussed.     

Induced ovulation and egg deposition in the direct developing anuran <Emphasis Type="Italic">Eleutherodactylus coqui</Emphasis>

This study investigates ovulation and egg deposition behaviors in the anuran Eleutherodactylus coqui from Puerto Rico in response to stimulation with gonadotropin and gonadotropin releasing hormones. Five hormones were tested by injection over a range of doses, including mammalian LHRH, avian LHRH, fish LHRH, D-Ala6, des-Gly10 ethylamide LHRH and hCG. We report a low level of ovulation and egg deposition in response to all hormones, with the most complete and consistent results from the non-natural D-Ala6, des-Gly10 ethylamide LHRH derivative. To confirm the viability of eggs produced in this manner we performed in vitro fertilization experiments that resulted in the development of normal frogs. Reproductive behaviors in E. coqui are apparently not controlled by a mammalian form of LHRH as reported in other common laboratory anuran species. D-Ala6, des-Gly10 ethylamide LHRH induces ovulation and deposition of mature and fertilizable eggs in E. coqui.