A prospective evaluation of atherosclerotic risk factors and hypercoagulability in young adults with premature lower extremity atherosclerosis

Purpose: Fifty-one consecutive patients with premature lower extremity atherosclerosis were prospectively evaluated for atherogenic risk factors and primary or acquired hypercoagulability, which might contribute to early ischemia and revascularization failure.Methods: Laboratory tests included plasma assays of (1) natural anticoagulants (NAC), lipoprotein (a) (Lp[a]), and anticardiolipin antibodies, and (2) fibrinolytic activators and inhibitors at baseline and stimulated after 20 minutes of upper extremity venous occlusion.Results: Forty-six (90%) of these 51 patients had laboratory abnormalities. One or more NAC deficiencies were found in 15 (30%) patients and included antithrombin III (n=5), protein C (n=8), protein S (n=4), and heparin cofactor II (n=2). Hypofibrinolysis was identified as a deficiency of stimulated tissue plasminogen activator in 22 (45%) patients and elevated plasminogen activator inhibitor-1 (PAI-1) in 29 (59%). Elevated Lp(a) was found in 43 (86%) patients. Five (10%) patients had anticardiolipin antibodies. Ten patients had combined NAC deficiency and hypofibrinolysis. Five (10%) patients had no abnormality. NAC deficiencies, especially protein C deficiency, were associated with acute ischemia (p<0.01), prior vascular intervention (p<0.01), an increasing number of total vascular procedures (p<0.01), and major amputation (p<0.01). PAI-1 was associated with a history of heart disease (p<0.05) and prior vascular procedures (p<0.05). Elevated Lp(a) was associated with elevated PAI-1 (p<0.05). Retesting in 20 patients suggested that 80% of NAC deficiencies were acquired, but abnormalities persisted in 66% of patients with elevated PAI-1 and in 93% of those with elevated Lp(a).Conclusions: These data strongly support the hypothesis that the convergence of atherogenic risk factors and hypercoagulability play an important role in early ischemia and poor results reported for lower extremity vascular procedures in young adults

Survival of young patients after abdominal aortic aneurysm repair

AbstractPurpose: This study assessed the cardiovascular disease, perioperative results, and survival after surgical abdominal aortic aneurysm repair in young patients (≤ 50 years) compared with randomly selected older patients who also underwent abdominal aortic aneurysm repair. Methods: We reviewed hospital records to identify young and randomly selected control patients (3 for each young patient, ≥ 65 years, matched for year of operation) with degenerative (atherosclerotic) abdominal aortic aneurysms undergoing repair between Jan 1, 1988, and Mar 31, 2000. Patients with congenital aneurysms, pseudoaneurysms, aortic dissections, post-coarctation dilations, aortic infection, arteritis, or aneurysms isolated to the thoracic aorta were excluded. Mortality data and cause of death were obtained from medical records and the National Death Index Results: Among 1168 patients who underwent abdominal aortic aneurysm repairs, 19 young patients (1.6%) and 57 control patients were identified. The mean age was 48.4 years in the young group and 72.2 years in the control group. There were no differences in sex or race between the two groups. When comparing existing cardiovascular disease between the groups, there were no differences in the incidence of earlier coronary revascularization (26% vs 16%) or non-cardiac vascular surgery (5% vs 9%), but aneurysms were more commonly symptomatic in young patients (53% vs 21%; P <.01). Aneurysmal disease was limited to the infrarenal aorta in similar proportions of patients (89% vs 88%). No statistically significant differences were seen in the incidence of perioperative deaths (16% young vs 9% control; P =.40) or postoperative complications (37% young vs 26% control; P =.38). The estimated survival rate of the young group was not different from that of the control group (3-year survival rate, 73% vs 69%; P =.32) or the entire cohort of patients (older than 50 years; n = 1101) who underwent repair of abdominal aortic aneurysms during the study period (3-year survival 73% vs 75%; P =.63) Conclusion: After abdominal aortic aneurysm repair, young patients had perioperative results and follow-up mortality rates similar to those of control patients. Cardiovascular disease was the predominant cause of death after abdominal aortic aneurysm repair in the young patients. When compared with an age older than 50 years at the time of abdominal aortic aneurysm repair, young age alone was not associated with increased survival. (J Vasc Surg 2002;35:94-9.

Measurement of inclusive D*+- and associated dijet cross sections in photoproduction at HERA

Inclusive photoproduction of D*+- mesons has been measured for photon-proton centre-of-mass energies in the range 130 < W < 280 GeV and a photon virtuality Q^2 < 1 GeV^2. The data sample used corresponds to an integrated luminosity of 37 pb^-1. Total and differential cross sections as functions of the D* transverse momentum and pseudorapidity are presented in restricted kinematical regions and the data are compared with next-to-leading order (NLO) perturbative QCD calculations using the "massive charm" and "massless charm" schemes. The measured cross sections are generally above the NLO calculations, in particular in the forward (proton) direction. The large data sample also allows the study of dijet production associated with charm. A significant resolved as well as a direct photon component contribute to the cross section. Leading order QCD Monte Carlo calculations indicate that the resolved contribution arises from a significant charm component in the photon. A massive charm NLO parton level calculation yields lower cross sections compared to the measured results in a kinematic region where the resolved photon contribution is significant.Comment: 32 pages including 6 figure

Measurement of Jet Shapes in Photoproduction at HERA

The shape of jets produced in quasi-real photon-proton collisions at centre-of-mass energies in the range $134-277$ GeV has been measured using the hadronic energy flow. The measurement was done with the ZEUS detector at HERA. Jets are identified using a cone algorithm in the $\eta - \phi$ plane with a cone radius of one unit. Measured jet shapes both in inclusive jet and dijet production with transverse energies $E^{jet}_T>14$ GeV are presented. The jet shape broadens as the jet pseudorapidity ($\eta^{jet}$) increases and narrows as $E^{jet}_T$ increases. In dijet photoproduction, the jet shapes have been measured separately for samples dominated by resolved and by direct processes. Leading-logarithm parton-shower Monte Carlo calculations of resolved and direct processes describe well the measured jet shapes except for the inclusive production of jets with high $\eta^{jet}$ and low $E^{jet}_T$. The observed broadening of the jet shape as $\eta^{jet}$ increases is consistent with the predicted increase in the fraction of final state gluon jets.Comment: 29 pages including 9 figure

High-E_T dijet photoproduction at HERA

The cross section for high-E_T dijet production in photoproduction has been measured with the ZEUS detector at HERA using an integrated luminosity of 81.8 pb-1. The events were required to have a virtuality of the incoming photon, Q^2, of less than 1 GeV^2 and a photon-proton centre-of-mass energy in the range 142 < W < 293 GeV. Events were selected if at least two jets satisfied the transverse-energy requirements of E_T(jet1) > 20 GeV and E_T(jet2) > 15 GeV and pseudorapidity requirements of -1 < eta(jet1,2) < 3, with at least one of the jets satisfying -1 < eta(jet) < 2.5. The measurements show sensitivity to the parton distributions in the photon and proton and effects beyond next-to-leading order in QCD. Hence these data can be used to constrain further the parton densities in the proton and photon.Comment: 36 pages, 13 figures, 20 tables, including minor revisions from referees. Accepted by Phys. Rev.

Measurement of the diffractive structure function in deep inelastic scattering at HERA

This paper presents an analysis of the inclusive properties of diffractive deep inelastic scattering events produced in $ep$ interactions at HERA. The events are characterised by a rapidity gap between the outgoing proton system and the remaining hadronic system. Inclusive distributions are presented and compared with Monte Carlo models for diffractive processes. The data are consistent with models where the pomeron structure function has a hard and a soft contribution. The diffractive structure function is measured as a function of \xpom, the momentum fraction lost by the proton, of $\beta$, the momentum fraction of the struck quark with respect to \xpom, and of $Q^2$. The \xpom dependence is consistent with the form \xpoma where $a~=~1.30~\pm~0.08~(stat)~^{+~0.08}_{-~0.14}~(sys)$ in all bins of $\beta$ and $Q^2$. In the measured $Q^2$ range, the diffractive structure function approximately scales with $Q^2$ at fixed $\beta$. In an Ingelman-Schlein type model, where commonly used pomeron flux factor normalisations are assumed, it is found that the quarks within the pomeron do not saturate the momentum sum rule.Comment: 36 pages, latex, 11 figures appended as uuencoded fil

An NLO QCD analysis of inclusive cross-section and jet-production data from the ZEUS experiment

The ZEUS inclusive differential cross-section data from HERA, for charged and neutral current processes taken with e+ and e- beams, together with differential cross-section data on inclusive jet production in e+ p scattering and dijet production in \gamma p scattering, have been used in a new NLO QCD analysis to extract the parton distribution functions of the proton. The input of jet data constrains the gluon and allows an accurate extraction of \alpha_s(M_Z) at NLO; \alpha_s(M_Z) = 0.1183 \pm 0.0028(exp.) \pm 0.0008(model) An additional uncertainty from the choice of scales is estimated as \pm 0.005. This is the first extraction of \alpha_s(M_Z) from HERA data alone.Comment: 37 pages, 14 figures, to be submitted to EPJC. PDFs available at http://durpdg.dur.ac.uk/hepdata in LHAPDFv

Measurement of event shapes in deep inelastic scattering at HERA

Inclusive event-shape variables have been measured in the current region of the Breit frame for neutral current deep inelastic ep scattering using an integrated luminosity of 45.0 pb^-1 collected with the ZEUS detector at HERA. The variables studied included thrust, jet broadening and invariant jet mass. The kinematic range covered was 10 < Q^2 < 20,480 GeV^2 and 6.10^-4 < x < 0.6, where Q^2 is the virtuality of the exchanged boson and x is the Bjorken variable. The Q dependence of the shape variables has been used in conjunction with NLO perturbative calculations and the Dokshitzer-Webber non-perturbative corrections (`power corrections') to investigate the validity of this approach.Comment: 7+25 pages, 6 figure

Inclusive jet cross sections and dijet correlations in D∗±D^{*\pm} photoproduction at HERA

Inclusive jet cross sections in photoproduction for events containing a $D^*$ meson have been measured with the ZEUS detector at HERA using an integrated luminosity of $78.6 {\rm pb}^{-1}$. The events were required to have a virtuality of the incoming photon, $Q^2$, of less than 1 GeV$^2$, and a photon-proton centre-of-mass energy in the range $130<W_{\gamma p}<280 {\rm GeV}$. The measurements are compared with next-to-leading-order (NLO) QCD calculations. Good agreement is found with the NLO calculations over most of the measured kinematic region. Requiring a second jet in the event allowed a more detailed comparison with QCD calculations. The measured dijet cross sections are also compared to Monte Carlo (MC) models which incorporate leading-order matrix elements followed by parton showers and hadronisation. The NLO QCD predictions are in general agreement with the data although differences have been isolated to regions where contributions from higher orders are expected to be significant. The MC models give a better description than the NLO predictions of the shape of the measured cross sections.Comment: 43 pages, 12 figures, charm jets ZEU