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.

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.

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

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 ß-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.

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.

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.

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.

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 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.