Genetic characterization of the zoonotic parasite Ancylostoma caninum in the central and eastern United States

Ancylostoma caninum is the most common nematode parasite of dogs in the United States. The present study aimed to describe the molecular epidemiology of A. caninum isolates from the central and eastern states of the United States using the partial mitochondrial cytochrome oxidase (cox1) gene and to compare them with those reported globally. We isolated eggs from faecal samples of dogs and characterized each isolate based on cox1 sequences. A total of 60 samples originating from Kansas, Iowa, New York, Florida and Massachusetts were included. 25 haplotypes were identified in the United States dataset with high haplotype diversity (0.904). Sequence data were compared to sequences from other world regions available in GenBank. Global haplotype analysis demonstrated 35 haplotypes with a haplotype diversity of 0.931. Phylogenetic and network analysis provide evidence for the existence of moderate geographical structuring of A. caninum haplotypes. Our results provide an updated summary of A. caninum haplotypes and data for neutral genetic markers with utility for tracking hookworm populations. Sequences have been deposited in GenBank (ON980650-ON980674). Further studies of isolates from other regions are essential to understand the genetic diversity of this parasite.

Chromatin-associated RNA sequencing (ChAR-seq) maps genome-wide RNA-to-DNA contacts

RNA is a critical component of chromatin in eukaryotes, both as a product of transcription, and as an essential constituent of ribonucleoprotein complexes that regulate both local and global chromatin states. Here, we present a proximity ligation and sequencing method called Chromatin-Associated RNA sequencing (ChAR-seq) that maps all RNA-to-DNA contacts across the genome. Using Drosophila cells, we show that ChAR-seq provides unbiased, de novo identification of targets of chromatin-bound RNAs including nascent transcripts, chromosome-specific dosage compensation ncRNAs, and genome-wide trans-associated RNAs involved in co-transcriptional RNA processing.

Final Test Results for the Ground Operations Demonstration Unit for Liquid Hydrogen

Described herein is a comprehensive project-a large-scale test of an integrated refrigeration and storage system called the Ground Operations and Demonstration Unit for Liquid Hydrogen (GODU LH2), sponsored by the Advanced Exploration Systems Program and constructed at Kennedy Space Center. A commercial cryogenic refrigerator interfaced with a 125,000 liter liquid hydrogen tank and auxiliary systems in a manner that enabled control of the propellant state by extracting heat via a closed loop Brayton cycle refrigerator coupled to a novel internal heat exchanger. Three primary objectives were demonstrating zero-loss storage and transfer, gaseous liquefaction, and propellant densification. Testing was performed at three different liquid hydrogen fill-levels. Data were collected on tank pressure, internal tank temperature profiles, mass flow in and out of the system, and refrigeration system performance. All test objectives were successfully achieved during approximately two years of testing. A summary of the final results is presented in this paper.

RNA-dependent stabilization of SUV39H1 at constitutive heterochromatin

Heterochromatin formed by the SUV39 histone methyltransferases represses transcription from repetitive DNA sequences and ensures genomic stability. How SUV39 enzymes localize to their target genomic loci remains unclear. Here, we demonstrate that chromatin-associated RNA contributes to the stable association of SUV39H1 with constitutive heterochromatin in human cells. We find that RNA associated with mitotic chromosomes is concentrated at pericentric heterochromatin, and is encoded, in part, by repetitive α-satellite sequences, which are retained in cis at their transcription sites. Purified SUV39H1 directly binds nucleic acids through its chromodomain; and in cells, SUV39H1 associates with α-satellite RNA transcripts. Furthermore, nucleic acid binding mutants destabilize the association of SUV39H1 with chromatin in mitotic and interphase cells – effects that can be recapitulated by RNase treatment or RNA polymerase inhibition – and cause defects in heterochromatin function. Collectively, our findings uncover a previously unrealized function for chromatin-associated RNA in regulating constitutive heterochromatin in human cells.

DOI:http://dx.doi.org/10.7554/eLife.25299.001

Each cell in a human body contains the same DNA sequence, which serves as a set of instructions for how the body should develop and operate. However, only certain sections of DNA are “active” at any particular time and in any given type of cell. When a section of DNA is active, cells make many copies of it using a molecule called RNA. When a section of DNA in inactive, very little RNA is made. Some sections of DNA must always be kept inactive to avoid damaging the cell.

DNA is packaged around proteins called histones, and enzymes that modify histones control which sections of DNA are switched on or off. One such modifying enzyme, called SUV39H1, is important for inactivating sections of DNA that could cause harm to the cell if they are active. Previous studies showed that the loss of SUV39H1 and related proteins cause abnormalities and cancer in mice. However, it is not clear how this enzyme identifies and inactivates the DNA it needs to target.

Johnson, Yewdell et al. studied SUV39H1 in human cells. The experiments show that RNA binds to the SUV39H1 enzyme and controls how it interacts with DNA. Specifically, Johnson, Yewdell et al. found that sections of DNA that are inactive can still make a small amount of RNA, and that this RNA tethers SUV39H1 to the DNA to keep the DNA switched off. Mutant forms of SUV39H1 that are unable to interact with RNA fall off the DNA, which allows DNA sequences that are normally switched off to become active.

The findings of Johnson, Yewdell et al. reveal a new role for RNAs in regulating whether DNA is switched on or off. The next step is to determine whether other enzymes that can also modify histones use the same mechanism to activate or inactivate DNA. Differences in how the activity of DNA is regulated between individuals plays a crucial role in generating the diversity we see in nature. Therefore, this work helps us to understand our basic biology and may provide new opportunities for treating disease.

DOI:http://dx.doi.org/10.7554/eLife.25299.002

RNA-mediated regulation of heterochromatin

The formation of condensed, transcriptionally repressed heterochromatin is essential for controlling gene expression throughout development, silencing parasitic DNA elements, and for genome stability and inheritance. Cells employ diverse mechanisms for controlling heterochromatin states through proteins that modify DNA and histones. An emerging theme is that chromatin-associated RNAs play important roles in regulating heterochromatin proteins by controlling their initial recruitment to chromatin, their stable association with chromatin, their spread along chromatin, or their enzymatic activity. Major challenges for the field include not only identifying regulatory RNAs, but understanding the underlying biochemical mechanisms for how RNAs associate with chromatin, the specificity of interactions between heterochromatin proteins and RNA, and how these binding events manifest in cells to orchestrate RNA-mediated regulation of heterochromatin.

Rise and fall of vector infectivity during sequential strain displacements by mosquito-borne dengue virus

Each of the four serotypes of mosquito-borne dengue virus (DENV-1-4) comprises multiple, genetically distinct strains. Competitive displacement between strains within a serotype is a common feature of DENV epidemiology and can trigger outbreaks of dengue disease. We investigated the mechanisms underlying two sequential displacements by DENV-3 strains in Sri Lanka that each coincided with abrupt increases in dengue haemorrhagic fever (DHF) incidence. First, the post-DHF strain displaced the pre-DHF strain in the 1980s. We have previously shown that post-DHF is more infectious than pre-DHF for the major DENV vector, Aedes aegypti. Then, the ultra-DHF strain evolved in situ from post-DHF and displaced its ancestor in the 2000s. We predicted that ultra-DHF would be more infectious for Ae. aegypti than post-DHF but found that ultra-DHF infected a significantly lower percentage of mosquitoes than post-DHF. We therefore hypothesized that ultra-DHF had effected displacement by disseminating in Ae. aegypti more rapidly than post-DHF, but this was not borne out by a time course of mosquito infection. To elucidate the mechanisms that shape these virus-vector interactions, we tested the impact of RNA interference (RNAi), the principal mosquito defence against DENV, on replication of each of the three DENV strains. Replication of all strains was similar in mosquito cells with dysfunctional RNAi, but in cells with functional RNAi, replication of pre-DHF was significantly suppressed relative to the other two strains. Thus, differences in susceptibility to RNAi may account for the differences in mosquito infectivity between pre-DHF and post-DHF, but other mechanisms underlie the difference between post-DHF and ultra-DHF.

Quantifying the origin of metallic glass formation

The waiting time to form a crystal in a unit volume of homogeneous undercooled liquid exhibits a pronounced minimum τ_X* at a ‘nose temperature' T^* located between the glass transition temperature T_g, and the crystal melting temperature, T_L. Turnbull argued that τ_X* should increase rapidly with the dimensionless ratio t_rg=T_g/T_L. Angell introduced a dimensionless ‘fragility parameter', m, to characterize the fall of atomic mobility with temperature above T_g. Both t_rg and m are widely thought to play a significant role in determining τ_X*. Here we survey and assess reported data for T_L, T_g, t_rg, m and τ_X* for a broad range of metallic glasses with widely varying τ_X*. By analysing this database, we derive a simple empirical expression for τ_X*(t_rg, m) that depends exponentially on t_rg and m, and two fitting parameters. A statistical analysis shows that knowledge of t_rg and m alone is therefore sufficient to predict τ_X* within estimated experimental errors. Surprisingly, the liquid/crystal interfacial free energy does not appear in this expression for τ_X*.

The crystal formation waiting time of a homogeneous supercooled liquid exhibits a pronounced minimum depending on temperature, and this minimum is a measure of glass forming ability. Here, the authors propose an expression for this minimum for all metallic glasses that depends only on two fitting parameters.

Recurrent point mutations in the kinetochore gene KNSTRN in cutaneous squamous cell carcinoma

Here we report the discovery of recurrent mutations concentrated at an ultraviolet signature hotspot in KNSTRN, which encodes a kinetochore protein, in 19% of cutaneous squamous cell carcinomas (SCCs). Cancer-associated KNSTRN mutations, most notably those encoding p.Ser24Phe, disrupt chromatid cohesion in normal cells, occur in SCC precursors, correlate with increased aneuploidy in primary tumors and enhance tumorigenesis in vivo. These findings suggest a role for KNSTRN mutagenesis in SCC development.

Isolation and characterization of Staphylococcus aureus strains from a Paso del Norte dairy

The primary purpose of this study was to determine if methicillin-resistant Staphylococcus aureus (MRSA) strains could be identified in the milk of dairy cattle in a Paso del Norte region dairy of the United States. Using physiological and PCR-based identification schemes, a total of 40 Staph. aureus strains were isolated from 29 raw milk samples of 133 total samples analyzed. Pulsed-field gel electrophoresis after digestion with the SmaI enzyme revealed that the 40 confirmed strains were represented by 5 pulsed-field types, which each contained 3 or more strains. Of 7 hospital strains isolated from cows undergoing antibiotic therapy, 3 demonstrated resistance to 3 or more antimicrobial classes and displayed similar pulsed-field gel electrophoresis patterns. A secondary purpose of this study was to elucidate the evolutionary relationships of strains isolated in this study to genomically characterized Staph. aureus strains. Therefore, Roche 454 GS (Roche Diagnostics Corp., Dallas, TX) pyrosequencing was used to produce draft genome sequences of an MRSA raw milk isolate (H29) and a methicillin-susceptible Staph. aureus (PB32). Analysis using the BLASTn database (http://blast.ncbi.nlm.nih.gov/) demonstrated that the H29 draft genome was highly homologous to the human MRSA strain JH1, yet the β-lactamase plasmid carried by H29 was different from that carried by JH1. Genomic analysis of H29 also clearly explained the multidrug resistance phenotype of this raw milk isolate. Analysis of the PB32 draft genome (using BLASTn) demonstrated that this raw milk isolate was most related to human MRSA strain 04-02981. Although PB32 is not a MRSA, the PB32 draft genome did reveal the presence of a unique staphylococcal cassette mec (SCCmec) remnant. In addition, the PB32 draft genome revealed the presence of a novel bovine staphylococcal pathogenicity island, SaPIbovPB32. This study demonstrates the presence of clones closely related to human and (or) bovine Staph. aureus strains circulating in a dairy herd.

Vibrational modes of GaN nanowires in the gigahertz range

Brillouin-light-scattering measurements and finite-element modeling of vibrational spectra in the range of 5-40 GHz are presented for an array of monocrystalline GaN nanowires with hexagonal cross sections. Analysis of the spectra is substantially complicated by the presence of a distribution of nanowire diameters. The measurements and calculations reveal a variety of modes with simple flexural, higher-order flexural, approximately 'plane-strain', approximately longitudinal and torsional displacement patterns that are similar to the corresponding modes of isotropic cylinders. The largest peaks in the spectra with acoustic angular wavenumbers in the range of 4 to ~15 μm(-1) were determined to arise from modes with relatively large transverse displacements, consistent with inelastic light scattering arising predominantly from surface ripple. These dominant modes have finite frequencies in the limit of zero wavenumber, corresponding to transverse standing waves. At higher wavenumbers, the spectra provide evidence for increased scattering through elasto-optic coupling, especially with respect to the emergence of a peak from a mode analogous to the longitudinal guided modes of thin films.

N-allyl-N-sulfonyl ynamides as synthetic precursors to amidines and vinylogous amidines. An unexpected N-to-C 1,3-sulfonyl shift in nitrile synthesis

A detailed study of amidine synthesis from N-allyl-N-sulfonyl ynamides is described here. Mechanistically, this is a fascinating reaction consisting of diverging pathways that could lead to deallylation or allyl transfer depending upon the oxidation state of palladium catalysts, the nucleophilicity of amines, and the nature of the ligands. It essentially constitutes a Pd(0)-catalyzed aza-Claisen rearrangement of N-allyl ynamides, which can also be accomplished thermally. An observation of N-to-C 1,3-sulfonyl shift was made when examining these aza-Claisen rearrangements thermally. This represents a useful approach to nitrile synthesis. While attempts to render this 1,3-sulfonyl shift stereoselective failed, we uncovered another set of tandem sigmatropic rearrangements, leading to vinyl imidate formation. Collectively, this work showcases the rich array of chemistry one can discover using these ynamides.

Disordered materials: a survey of amorphous solids

A brief historical perspective and a review of the current research on amorphous or glassy materials are presented. Glass formation by natural processes and by laboratory synthesis techniques is described. Recent efforts to characterize and model the atomic scale structure of amorphous phases are surveyed. The relation between amorphous and liquid states is emphasized in a discussion of thermodynamics and kinetics. The topic of crystal-to-glass transformation in the solid state and the related issue of crystal stability and melting are discussed.

Elastic constants and dimensions of imprinted polymeric nanolines determined from Brillouin light scattering

Elastic constants and cross-sectional dimensions of imprinted nanolines of poly(methyl methacrylate) (PMMA) on silicon substrates are determined nondestructively from finite-element inversion analysis of dispersion curves of hypersonic acoustic modes of these nanolines measured with Brillouin light scattering. The results for the cross-sectional dimensions, under the simplifying assumption of vertical sides and a semicircular top, are found to be consistent with dimensions determined from critical-dimension small-angle x-ray scattering measurements. The elastic constants C(11) and C(44) are found to be, respectively, 11.6% and 3.1% lower than their corresponding values for bulk PMMA. This result is consistent with the dimensional dependence of the quasi-static Young's modulus determined from buckling measurements on PMMA films with lower molecular weights. This study provides the first evidence of size-dependent effects on hypersonic elastic properties of polymers.

A Rhodium(I)-Xylyl-BINAP Catalyzed Asymmetric Ynamide-[2 + 2 + 2] Cycloaddition in the Synthesis of Optically Enriched N,O-Biaryls

A rhodium(I)-xylyl-BINAP catalyzed asymmetric [2 + 2 + 2] cycloaddition of achiral conjugated aryl ynamides with various diynes is described here. This asymmetric cycloaddition provides a series of structurally interesting chiral N,O-biaryls with excellent enantioselectivity along with a modest diastereoselectivity with respect to both C-C and C-N axial chirality.

Synthesis of alpha-keto-imides via oxidation of ynamides

A de novo preparation of alpha-keto-imides via ynamide oxidation is described. With a number of alkyne oxidation conditions screened, a highly efficient RuO2-NaIO4 mediated oxidation and a DMDO oxidation have been identified to tolerate a wide range of ynamide types. In addition to accessing a wide variety of alpha-keto-imides, the RuO2-NaIO4 protocol provides a novel entry to the vicinal tricarbonyl motif via oxidation of push-pull ynamides, and imido acylsilanes from silyl-substituted ynamides. Chemoselective oxidation of ynamides containing olefins can be achieved by using DMDO, while the RuO2-NaIO4 protocol is not effective. These studies provide further support for the synthetic utility of ynamides.

A highly stereoselective synthesis of chiral alpha-amino-beta-lactams via the Kinugasa reaction employing ynamides

A highly stereoselective synthesis of chiral alpha-amino-beta-lactam through an ynamide-Kinugasa reaction is described. In addition, a mechanistic model is illustrated here to rationalize the observed diastereoselectivity, which depends on both the initial [3 + 2] cycloaddition step and the subsequent protonation for which both are highly selective.

Mode-selective acoustic spectroscopy of trigonal piezoelectric crystals

A noncontacting electromagnetic-acousticresonance technique is presented for generating and detecting vibrational modes with prescribed symmetries in piezoelectric trigonal crystals with cylindrical geometry. This technique provides the experimental basis for determining all elastic constants from a single specimen, while overcoming difficulties in mode identification that can occur in traditional resonant-ultrasound spectroscopy. Narrow-band tone-burst excitation and piezoelectric coupling are employed with various geometrical configurations of electrodes near the surface of a quartz specimen. The geometries of the specimen and plates include all of the symmetry elements of the crystallographic point group, which enable selection of the irreducible representation of excited vibrational modes simply by switching electrical leads to the electrodes.

Stereochemical Control of Both C−C and C−N Axial Chirality in the Synthesis of Chiral N,O-Biaryls

A Rh(I)-catalyzed asymmetric [2 + 2 + 2] cycloaddition of achiral ynamides is described here. This work demonstrates a unique concept of stereochemical control of both the C-C and C-N axial chirality and provides an approach to the synthesis of chiral N,O-biaryls as well as chiral anilides.

A Rhodium(I)-Catalyzed Demethylation−Cyclization of o-Anisole-Substituted Ynamides in the Synthesis of Chiral 2-Amido Benzofurans

A Rh(I)-catalyzed demethylation-cyclization sequence for a direct transformation of o-anisole-substituted ynamides to benzofurans is described here. The Ag salt functions synergistically with Rh(I) for the key demethylation step.

4‘-Substituted-4-biphenylyloxenium Ions: Reactivity and Selectivity in Aqueous Solution

Azide trapping shows that the 4'-substituted-4-biphenylyloxenium ions 1b-d are generated during hydrolysis of 4-aryl-4-acetoxy-2,5-cyclohexadienones, 2c and 2d, and O-(4-aryl)phenyl-N-methanesulfonylhydroxylamines, 3b and 3c. In addition, the 4'-bromo-substituted ester, 2d, undergoes a kinetically second-order reaction with N3- that accounts for a fraction of the azide adduct, 5d. Since both first-order and second-order azide trapping occurs simultaneously in 2d, the second-order reaction is not enforced by the short lifetime of 1d, which has similar azide/solvent selectivity to the unsubstituted ion, 1a. In contrast the 4'-CN and 4'-NO2 ions 1e and 1f cannot be detected by azide trapping during the hydrolysis of the dichloroacetic acid esters 2e' and 2f' even though 18O labeling experiments show that a fraction of the hydrolysis of both esters occurs through C(alkyl)-O bond cleavage. These esters exhibit only second-order trapping by azide. Correlations of the azide/solvent selectivities of 1a-d with the calculated relative driving force for hydration of the ions (DeltaE of eq 4) determined at the pBP/DN//HF/6-31G and BP/6-31G//HF/6-31G levels of theory suggest that 1e and 1f have lifetimes in the 1-100 ps range. Ions with these short lifetimes are not in diffusional equilibrium with nonsolvent nucleophiles, and must be trapped by such nucleophiles via a preassociation mechanism. The second-order trapping that is observed in these two cases is enforced by the short lifetime of the cations, and may occur by a concerted S(N)2' mechanism or by internal azide trapping of an ion sandwich produced by azide-assisted ionization. Comparison of azide/solvent selectivities of the oxenium ions 1a-c with the corresponding biphenylylnitrenium ions 8a-c shows that 4'-substituent effects on reactivity in both sets of ions are similar in magnitude, although the nitrenium ions are ca. 30-fold more stable in an aqueous environment than the corresponding oxenium ions. The magnitude of the 4'-substituent effects for electron-donating substituents suggest that both sets of ions are more accurately described as 4-aryl-1-imino-2,5-cyclohexadienyl or 4-aryl-1-oxo-2,5-cyclohexadienyl carbocations. Calculated structures of the oxenium ions are also consistent with this interpretation.

A universal criterion for plastic yielding of metallic glasses with a (T/Tg) 2/3 temperature dependence

Room temperature (TR) elastic constants and compressive yield strengths of approximately 30 metallic glasses reveal an average shear limit gammaC=0.0267+/-0.0020, where tauY=gamma CG is the maximum resolved shear stress at yielding, and G the shear modulus. The gammaC values for individual glasses are correlated with t=TR/Tg , and gamma C for a single glass follows the same correlation (vs t=T/Tg). A cooperative shear model, inspired by Frenkel's analysis of the shear strength of solids, is proposed. Using a scaling analysis leads to a universal law tauCT/G=gammaC0-gammaC1(t)2/3 for the flow stress at finite T where gammaC0=(0.036+/-0.002) and gammaC1=(0.016+/-0.002).

Procedural outcomes and long-term survival among patients undergoing percutaneous coronary intervention of a chronic total occlusion in native coronary arteries: a 20-year experience

OBJECTIVES

The study compared procedural outcomes and long-term survival for patients undergoing percutaneous coronary intervention (PCI) of a chronic total coronary artery occlusion (CTO) with a matched non-CTO cohort to determine whether successful PCI of a CTO is associated with improved survival.

BACKGROUND

Percutaneous coronary intervention of a CTO is a common occurrence, and the long-term survival for patients with successful PCI of a CTO has not been clearly defined.

METHODS

Between June 1980 and December 1999, a total of 2,007 consecutive patients underwent PCI for a CTO. Utilizing propensity scoring methods, a matched non-CTO cohort of 2,007 patients was identified and compared to the CTO group. The cohorts were stratified into successful and failed procedures.

RESULTS

The in-hospital major adverse cardiac event (MACE) rate was 3.8% in the CTO cohort. Technical success has improved over the last 10 years (overall 74.4%, slope 1.0%/yr, p = 0.02, R2 = 49.9%) as did procedural success (overall 69.9%, slope 1.2%/yr, p = 0.02, R2 = 51.5%) without a concomitant increase in in-hospital MACE rates (slope 0.1%/yr, p = 0.7). There was a distinct 10-year survival advantage for successful CTO treatment compared with failed CTO treatment (73.5% vs. 65.1%, p = 0.001). The CTO versus non-CTO 10-year survival was the same (71.2% vs. 71.4%, p = 0.9). Diabetics in the CTO cohort had a lower 10-year survival compared with nondiabetics (58.3% vs. 74.3%, p < 0.0001).

CONCLUSIONS

These data represent follow-up of the largest reported series of patients undergoing PCI for a CTO. The 10-year survival rates for matched non-CTO and the CTO cohorts were similar. Success rates have continued to improve without an accompanying increase in MACE rates. A successfully revascularized CTO confers a significant 10-year survival advantage compared with failed revascularization.

Microstructure controlled shear band pattern formation and enhanced plasticity of bulk metallic glasses containing in situ formed ductile phase dendrite dispersions

Results are presented for a ductile metal reinforced bulk metallic glass matrix composite based on glass forming compositions in the Zr-Ti-Cu-Ni-Be system. Primary dendrite growth and solute partitioning in the molten state yields a microstructure consisting of a ductile crystalline Ti-Zr-Nb beta phase, with bcc structure, in a Zr-Ti-Nb-Cu-Ni-Be bulk metallic glass matrix. Under unconstrained mechanical loading organized shear band patterns develop throughout the sample. This results in a dramatic increase in the plastic strain to failure, impact resistance, and toughness of the metallic glass.

Global linkages in animal agriculture: new opportunities for United States agricultural universities

Today's rapidly changing world offers new opportunities for Departments of Animal Science that wish to expand their international activity. Seeking a relevant role in the definition of sustainable agriculture, internationalizing courses and curricula for all students, supporting private sector enterprises at home and abroad (export promotion), maintaining collaboration with former students, and providing better information to our farmers and citizens about world conditions: these are some of the challenges now facing us. A survey of heads of departments of animal science at universities in the United States revealed that of 64 respondents, almost all report significant international activities. However, only 20% are satisfied with their present activity level, and 80% intend to seek an expanded international role. The expected benefits from international activity most often mentioned were a broadened faculty experience and a better capacity to prepare students for the 21st century. Anticipated problems are related to faculty and departmental recognition, faculty career trajectories, and continuity of work assignments. On balance, respondents overwhelmingly believe that expected benefits outweigh possible problems. Eighty percent of respondents reported a generally supportive attitude from their administration, but 75% indicated that the department itself needs to provide leadership in the search for new international linkages.

Results of direct percutaneous transluminal coronary angioplasty in octogenarians

Direct percutaneous transluminal coronary angioplasty (PTCA) has emerged as effective reperfusion therapy for acute myocardial infarction; however, few data exist on its use in octogenarians. Thrombolytic therapy in this age group has reduced early mortality from approximately 30% to 20%, but is associated with an increased risk of stroke and major hemorrhage. We analyzed the acute and long-term results of direct PTCA performed on patients aged > or = 80 years at our institution between 1980 and 1993. The study group consisted of 55 patients (mean patient age 83.3 +/- 2.3 years). Infarcts were anterior in 27 patients (49%). Cardiogenic shock was present in 6 patients (11%). The mean time to reperfusion was 4.3 +/- 2.8 hours. Direct PTCA was successful in 53 patients (96%). There were no emergent bypass operations. In-hospital death occurred in 9 patients (16%), including 4 of 6 (67%) presenting in cardiogenic shock and 5 of 49 (10%) who were hemodynamically stable on presentation. Repeat PTCA for recurrent ischemia was performed in 6 patients (11%). There were no strokes during hospitalization. Bleeding complications requiring blood transfusion were present in 4 patients (7%). Thirty-day mortality was 16% and 1-year actuarial survival was 67%. Direct PTCA in patients aged > or = 80 years can be performed safely with a high procedural success rate. The clinical outcome with PTCA in this high risk subset of patients compares favorably with that reported previously for both thrombolytic and medical therapy.

Directional atherectomy of left main stenoses

Balloon angioplasty (PTCA) of left main (LM) stenoses is limited by frequent clinical restenosis. Directional coronary atherectomy (DCA) may be an effective alternative to PTCA due to its ability to achieve a greater postprocedural luminal diameter when treating bulky, eccentric plaques and aorto-ostial lesions. We analyzed the acute and long-term results following 24 DCA procedures in 22 patients with "protected" LM lesions. Acute success (residual stenosis < or = 40%, no major ischemic complications) was 88% overall, 100% in 13 planned procedures, and 73% in 11 adjunctive DCA procedures that followed suboptimal PTCA. Mean LM stenosis was reduced from 86% to 13% (P < 0.01). There were no procedural complications directly attributed to DCA. At a mean of 24 +/- 3 months, the clinical restenosis rate was 16%, survival was 100%, and event-free survival (freedom from death, MI, or repeat lesion-related interventions) was 89%. We conclude that DCA in protected LM lesions (1) can achieved excellent angiographic results with low procedural complication rates, (2) may succeed where PTCA yields suboptimal results, and (3) may provide late clinical outcomes superior to those of balloon angioplasty.

Initial and long-term outcome of 83 patients after balloon angioplasty of totally occluded bypass grafts

OBJECTIVES

This study was designed to evaluate the safety and short- and long-term results of coronary angioplasty of totally occluded bypass grafts in patients with clinical conditions other than acute myocardial infarction.

BACKGROUND

Total occlusion of bypass grafts after coronary artery surgery often causes recurrent ischemia. The safety and results of percutaneous transluminal coronary angioplasty in occluded bypass grafts are controversial.

METHODS

All patients with dilation of a totally occluded bypass graft attempted between 1981 and 1991 were retrospectively identified from a data base. Patients treated in the setting of an acute myocardial infarction were excluded. Eighty-three patients met these criteria and constitute the study group. Hospital records, office charts and procedural reports were reviewed in all patients to supplement details available in the data base.

RESULTS

The time from bypass surgery to attempted coronary angioplasty ranged from 1 to 226 months (mean time 88 months). The mean (+/- SD) duration of graft occlusion was 31 +/- 46 days (range 1 to 180). In 27 attempts the bypass graft was the only site dilated, and in 56 attempts (68%) one to six other sites (n = 101) were dilated. Angiographic success (< or = 40% residual lumen stenosis) was achieved in 61 grafts (73%) and 98 of the additional sites (97%) (p < 0.001). Major complications included one procedural death and two Q wave infarctions. Follow-up for a mean of 32 months demonstrated a 1- and 3-year actuarial survival rate of 94% and 80%, respectively. At 3 years, only 34% of patients were free of repeat angioplasty or surgery.

CONCLUSIONS

Angioplasty of totally occluded bypass grafts can be successful in the majority of selected patients, although major complications can occur. Strategies for sustained patency are needed to improve the long-term results.

Failed direct coronary angioplasty for acute myocardial infarction: in-hospital outcome and predictors of death

OBJECTIVES

The purpose of this study was to compare the mechanisms, predictors and outcome of patients with failed direct coronary angioplasty of the infarct-related artery with those in patients with successful direct angioplasty.

BACKGROUND

Direct coronary angioplasty of the infarct-related artery, without antecedent thrombolytic therapy, is an effective treatment for patients with acute myocardial infarction. Concern has been expressed over high mortality rates in patients with failed direct infarct angioplasty.

METHODS

All patients treated by angioplasty were prospectively entered into a computer data base. The characteristics and outcome of all patients with failed direct angioplasty were reviewed and compared with those of patients with successful direct angioplasty.

RESULTS

Direct angioplasty was successful in 705 (94%) of 750 patients and unsuccessful in 45 (6%). Patients in the failure group were more likely to be in cardiogenic shock (22% vs. 7%, p < 0.003), to have had a previous myocardial infarction (44% vs. 28%, p < 0.03) and to have three-vessel coronary artery disease (44% vs. 23%, p < 0.003). Age, gender, ejection fraction, previous bypass surgery and diabetes mellitus were similar in both groups. Only the presence of multivessel coronary artery disease (p < 0.004) and cardiogenic shock (p < 0.025) were independent predictors of failed direct angioplasty. In-hospital death (31% vs. 4.8%, p < 0.001) and the need for emergency coronary artery bypass surgery (27% vs. 0.5%, p < 0.0001) were more frequent in patients with unsuccessful than in patients with successful direct angioplasty. Patients with failed direct angioplasty and in-hospital death usually had multiple high risk characteristics, including cardiogenic shock (50%), previous myocardial infarction (43%) and multivessel coronary artery disease (93%).

CONCLUSIONS

Direct coronary angioplasty is an effective method for establishing reperfusion in acute myocardial infarction. Procedural failure is infrequent, usually occurring in patients with high risk baseline characteristics.

Effects of undernutrition and refeeding on weights of body parts and chemical components of growing Moroccan lambs

Forty-four intact, male lambs (20 Timahdit and 24 D'man) were used to assess the effects of 22% (from approximately 25 to approximately 20 kg) and 31% (from approximately 25 to approximately 17 kg) live weight loss and the subsequent refeeding to initial BW on changes in body components. Body composition was determined using a serial slaughter technique at 17, 20, and 25 kg live weight during normal growth, weight loss, and refeeding phases. Reduction in live weight from 25 to 20 kg was associated with greater loss of visceral organs (30%) and internal fat (75%) than carcass loss (19%). Further body weight loss (from 20 to 17 kg) involved carcasses to a greater extent than internal organs. The composition of BW loss consisted of 53% water, 28% fat, and 15% protein. Refeeding was associated with a rapid increase in organ weights and less fat regeneration. Although total internal organs recovered only 90% of their original weight, liver and kidneys regained all their weight. At the same slaughter weight, carcass and noncarcass components of refed lambs were leaner because of lower fat content in these components.

Effects of compensatory growth on some body component weights and on carcass and noncarcass composition of growing lambs

A trial was conducted in 1983 and repeated in 1984 to measure effects of restricted feed intake and realimentation on weights of organs and on carcass and noncarcass composition. A total of one hundred six weaned lambs from two breeds (Timahdit and D'man) and a breed cross (Ile de France x D'man) were used in both years. Lambs were allotted to one of six feed intake regimens: HH (ad libitum access to feed from 21 to 30 kg); HM (ad libitum access to feed from 21 to 26 kg then 70% ad libitum to 30 kg); MH (70% ad libitum from 21 to 26 kg then ad libitum to 30 kg); MM (70% ad libitum from 21 to 30 kg); LH (restricted to lose weight from 21 to 17 kg then ad libitum to 30 kg); and LM (restricted to lose weight from 21 to 17 kg then 70% ad libitum to 30 kg). Weights of visceral organs and mesenteric and kidney fat showed dramatic responses to alteration of feed allowances. After recovery from 20% live weight loss, weight of liver equaled or exceeded that of both the ad libitum and 70% refed lambs. Mesenteric and kidney fat did not. Refeeding was accompanied by an increase in water (P less than .05) and a decrease in fat (P less than .01) of both carcass and noncarcass components. These results indicate that weight loss of lambs incurred during feed shortage was largely in internal organ weights, and that these lambs can recover these losses during realimentation and undergo compensatory growth with better feed efficiency and lean carcasses.

Orthopedic experience in a MASH unit in postwar Iraq

The orthopedic experience of a U.S. Army MASH unit deployed in southern Iraq is discussed. Seventy major casualties were surgically treated in a short time span. A high percentage of extremity trauma was observed (69%). Many patients had multiple extremity involvement. The emergency wartime surgical treatment of four specific types of trauma is explored. A new algorithm is presented for the rapid evaluation of penetrating joint injuries. We summarize the current concepts of war surgery as they apply to orthopedic injuries, and add specific observations from this experience.

Myocardial salvage with direct coronary angioplasty for acute infarction

To assess the changes in myocardial function following direct coronary angioplasty, we evaluated 323 consecutive patients undergoing coronary angioplasty without antecedent thrombolytic therapy for acute myocardial infarction. Left ventricular function was evaluated using contrast ventriculography immediately preangioplasty and at the time of predismissal follow-up angiography (a mean of 7 days after infarction). The global ejection fraction increased from 52.6% to 58.9% (p less than 0.0005). Multivariate correlates of improved global left ventricular function included baseline ejection fraction less than or equal to 45%, and a patent infarct vessel at the time of predischarge follow-up angiography. Systolic function in the infarct zone improved by a mean of 30%. Logistic regression analysis identified sustained infarct vessel patency and anterior myocardial infarction as multivariate correlates of improved regional function in the infarct zone. In patients presenting with baseline ejection fractions less than or equal to 40%, the mean ejection fraction increased from 28% to 42%. Long-term survival was compromised in patients with global ejection fractions of less than or equal to 40% at the time of dismissal. Thus significant improvement in left ventricular function can be expected in the majority of patients undergoing direct infarct angioplasty. The myocardial salvage appears to be most significant in patients suffering large infarctions, and in those with sustained infarct vessel patency.

Safety and efficacy of percutaneous transluminal coronary angioplasty in patients with left ventricular dysfunction

The risks and long-term outcome after 845 elective percutaneous transluminal coronary angioplasties (PTCA) in patients with left ventricular (LV) dysfunction (ejection fraction less than or equal to 40%) were examined. Procedural results were compared with 8,117 consecutive procedures in patients with ejection fractions greater than 40%. The patients with LV dysfunction were older (63 vs 60 years, p less than 0.01), had a greater incidence of prior myocardial infarction (84 vs 45%, p less than 0.001), prior bypass surgery (39 vs 21%, p less than 0.001), 3-vessel disease (62 vs 33%, p less than 0.001), and class IV angina (48 vs 41%, p less than 0.01) than the control group. Angiographic success was lower (93 vs 95%, p less than 0.01), and overall procedural mortality was increased ( 4 vs 1%, p less than 0.001) in the study group. Emergency surgery rates were identical (2%). No significant difference was found in rates of nonfatal Q-wave myocardial infarction (2 vs 1%). At mean follow-up of 33.5 months, 15% of the patients with LV dysfunction required late bypass surgery, 27% underwent repeat PTCA, and 59% were angina free. Actuarial survival at 1 and 4 years was 87 and 69%, respectively. Cox regression analysis identified 3-vessel disease, age greater than or equal to 70 years, class IV angina and incomplete revascularization as correlates of long-term mortality. These data suggest that PTCA may be an effective treatment for coronary artery disease in patients with LV dysfunction.

Results of multivessel percutaneous transluminal coronary angioplasty in persons aged 65 years and older

Between 1981 and 1990, 1,373 patients, aged greater than or equal to 65 years (mean 71.2 +/- 4.9), underwent 1,640 multivessel percutaneous transluminal coronary angioplasty (PTCA) procedures. Of these, 224 patients (13.6%) had a left ventricular ejection fraction less than or equal to 40%, 412 (25.1%) had prior coronary artery bypass grafting (CABG) and 48 (2.9%) had left main artery dilatation. Of the 1,640 PTCA procedures, 697 were in patients with 2-vessel disease and 943 were in patients with 3-vessel disease. A mean 3.5 lesions were dilated per patient, with an overall angiographic success rate of 96%. Complete revascularization was achieved in 857 (52%). A total of 52 patients (3.2%) had a major in-hospital complication: 27 patients (1.6%) died, 24 (1.4%) had a Q-wave myocardial infarction, and 14 (0.8%) underwent emergent CABG. Stepwise logistic regression analysis identified ejection fraction less than or equal to 40% (p less than or equal to 0.001), 3-vessel disease (p less than or equal to 0.01), female gender (p less than or equal to 0.02), and PTCA between 1981 and 1985 (p less than or equal to 0.05) as independent predictors of mortality. Of the 1,373 patients, 1,023 have been followed for greater than or equal to 1 year (mean follow-up 32.5 +/- 21.3 months). There were 156 (15.2%) late deaths, 81 (7.9%) recurrent myocardial infarctions, and 162 (15.8%) coronary artery bypass operations. Actuarial survival, computed from the time of hospital discharge, was 92% at 1 year, 86% at 3 years and 78% at 5 years. Repeat PTCA was required in 371 patients (36.3%).(ABSTRACT TRUNCATED AT 250 WORDS)