1,995 research outputs found
Higgs Boson Discovery and Properties
We outline issues examined and progress made by the Light Higgs Snowmass 1996
working group regarding discovering Higgs bosons and measuring their detailed
properties. We focused primarily on what could be learned at LEP2, the Tevatron
(after upgrade), the LHC, a next linear \epem collider and a \mupmum
collider.Comment: 47 pages, full postscript file also available via anonymous ftp at
ftp://ucdhep.ucdavis.edu/gunion/summary_snowmass96.ps To appear in
``Proceedings of the 1996 DPF/DPB Summer Study on New Directions for High
Energy Physics''. Minor revisions of references and wording have been made in
a few place
Thromboxane biosynthesis in stroke and post-stroke dementia
With 25 to 30 thousand new patients per year and an incidence of
170/100.000, stroke is a major health problem in the Netherlands, as it is in
other western countries. It accounts for almost I 0% of the annual death in
the Netherlands. Approximately 80% of stroke is of ischemic origin, and
20% cerebral hemorrhage. For the individual patient, the consequences of
stroke are often devastating. Approximately 20% of the patients do not
survive the first weeks and case fatality at I year is approximately 35%1
However, mortality strongly depends on type of stroke, and is higher in
hemorrhagic than in ischemic cases. Of the survivors, only 65% is
discharged home directly. Approximately 15% is discharged to a nursery
home, and 20% to a stroke recovery or a rehabilitation center2 Even patients
who are discharged to their own home are often not able to live fully
independently, partly due to their physical handicap, but often also due to
cognitive impairment. In approximately 25% of the cases, cognitive
dysfunction is severe enough to the extent that patients fulfill all criteria of
dementia. Although the highest incidence of ischemic stroke is between
the 6'h and 7'h decade oflife, it is a disease of all ages. In subjects between 15
and 4 5 years of age, the incidence of ischemic stroke is between 6 and
15/1OO.OOO/year. The mortality in this group of relatively young adults, is
about 20% in the first 6 years after stroke and only less than half of the
survivors is eventually able to perform a job. Although the consequences of
stroke are often dramatic for the individual patient, these figures also
indicate the large burden of stroke on the community and the health care
system. As a result of the high incidence of stroke, a relatively small
reduction of a few percent of stroke or stroke recurrence would mean a large
reduction in number of patients appealing to the health care system in
absolute terms. Obviously, this makes every effort reducing the incidence or
recurrence of stroke, even with only a few percent, more than worthwhil
Efficacy of the epidural blood patch for the treatment of post lumbar puncture headache BLOPP: A randomised, observer-blind, controlled clinical trial [ISRCTN 71598245]
BACKGROUND: Post dural punction headache (PDPH) occurs in 10% to 40% of the patients who had a lumbar puncture. Its symptoms can be severe and incapacitating. The epidural blood patch is widely accepted as the treatment of choice for postdural puncture headache. Uncontrolled studies report rapid recovery after patching in 90% to 100% of treated patients. However, sufficient evidence from randomised, controlled clinical trials is lacking. METHODS: BLOPP (blood patch for post dural puncture headache) is a randomised, single centre, observer-blind clinical trial. Patients with PDPH for at least 24 hours and at most 7 days after lumbar puncture will be randomised to treatment with an epidural blood patch (EDBP) or to conventional treatment, i.e. 24 hours bed rest and ample fluid intake. PDPH 24 hours after treatment, classified on a 4-point scale (no, mild, moderate, severe) is the primary outcome. The secondary outcome is the presence of PDPH 7 days after treatment. We estimated that a sample size of 2 × 20 patients would provide us with a power of 80% to detect a relative reduction in number of patients with persisting PDPH after 24 hours of 50% at the usual significance level α = 5%, taking into account that in approximately 10% of the patients the PDPH will have resolved spontaneously after one day. DISCUSSION: The EDBP is accepted as the treatment of choice for PDPH although randomised, controlled data is scarce. Our randomised, observer-blind clinical trial enables us to compare the efficacy of two clinically practiced methods of PDPH treatment; EDBP versus conventional treatment, as they are applied in clinical practise
CPT violation and B-meson oscillations
Recent evidence for anomalous CP violation in B-meson oscillations can be
interpreted as resulting from CPT violation. This yields the first sensitivity
to CPT violation in the B_s^0 system, with the relevant coefficient for CPT
violation constrained at the level of parts in 10^{12}.Comment: 4 pages two-column REVTeX; Rapid Communications, Physical Review D,
in pres
Interobserver agreement for 10% categories of angiographic carotid stenosis
BACKGROUND AND PURPOSE: Although the reliability of the assessment of severe 70% to 99% carotid stenosis by carotid angiography has been proven excellent, this may not necessarily be the case for a more detailed classification of carotid stenoses by 10% categories.
METHODS: Angiograms of the carotid arteries were assessed pairwise by three independent, experienced observers. The measurements of the degree of stenosis of both the carotid bifurcation and the internal carotid artery were made according to the European Carotid Surgery Trial method. Kappa statistics were used to assess the agreement beyond chance for severe (70% to 99%) carotid stenosis (kappa 1) and for 10% categories of carotid stenosis (kappa 2). The penalty scores were adjusted by weights for the relative difference in risk (RDR) of stroke in the ipsilateral carotid distribution between the 10% categories (kappa 3). An adjustment of the RDR method was made by assuming that only patients with a severe carotid stenosis would undergo surgery, and the penalty would be 0 if no disagreement would exist about the indication for surgery (kappa 4). An even further adjustment (kappa 5) was made by assuming that assessment of the rate of carotid stenosis by one or both observers would lead to different treatment recommendations in 50% of the cases, and accordingly the penalty for disagreement (RDR) was halved.
RESULTS: One hundred twenty-one carotid bifurcations in 65 patients with a transient ischemic attack or nondisabling stroke were assessed. The intraclass correlation between the exact estimates of carotid stenosis was .90 (95% confidence interval, .85 to .92). The mean difference in stenosis between the two raters was 0.8% (95% confidence interval, -2.1% to 3.7%). kappa 1 to kappa 5 equaled 0.80, 0.40, 0.79, 0.91, and 0.92, respectively.
CONCLUSIONS: Interobserver agreement for distinct 10% categories of angiographic carotid stenosis is moderate, but when realistic risk- and decision-based weights are used, agreement between experienced observers can be almost perfect
Synthesis and solution properties of poly(p,α dimethylstyrene-co-maleic anhydride):The use of a monomer potentially obtained from renewable sources as a substitute of styrene in amphiphilic copolymers
The use of p,α-dimethylstyrene, potentially obtainable from renewable sources, as a substitute for styrene in the synthesis of amphiphilic copolymers is reported in this work. A series of novel poly(p,α-dimethylstyrene-co-maleic anhydride) (SMA) copolymers was synthesized, characterized, and studied as potential polymeric surfactants. After hydrolysis, the copolymers solution properties were compared to the similar and very well-known styrene-maleic acid copolymers. Both series of copolymers were synthesized using reversible addition-fragmentation chain transfer-mediated polymerization (RAFT), and a sample of poly(p,α-dimethylstyrene-co-maleic anhydride) was synthesized via classical free radical polymerization. The synthesized copolymers were studied from the point of view of their solution properties, with particular attention to the influence of the macromolecular and chemical structure on the surface tension of their aqueous solutions. Our results suggest that p,α-dimethylstyrene can be employed in copolymers with maleic anhydride, the resulting material being a valid alternative to SMA copolymers for various applications, such as emulsifiers and dispersants. Furthermore, the DMSMA series seems to be slightly more surface active than SMA
Magnesium sulfate in aneurysmal subarachnoid hemorrhage: a randomized controlled trial
BACKGROUND AND PURPOSE: Magnesium reverses cerebral vasospasm and reduces infarct volume after experimental subarachnoid hemorrhage (SAH) in rats. We aimed to assess whether magnesium reduces the frequency of delayed cerebral ischemia (DCI) in patients with aneurysmal SAH. METHODS: Patients were randomized within 4 days after SAH. Magnesium sulfate therapy consisted of a continuous intravenous dose of 64 mmol/L per day, to be started within 4 days after SAH and continued until 14 days after occlusion of the aneurysm. The primary outcome DCI (defined as the occurrence of a new hypodense lesion on computed tomography compatible with clinical features of DCI) was analyzed according to the "on-treatment" principle. For the secondary outcome measures "poor outcome" (Rankin >3) and "excellent outcome" (Rankin 0), we used the "intention-to-treat" principle. RESULTS: A total of 283 patients were randomized. Magnesium treatment reduced the risk of DCI by 34% (hazard ratio, 0.66; 95% CI, 0.38 to 1.14). After 3 months, the risk reduction for poor outcome was 23% (risk ratio, 0.77; 95% CI, 0.54 to 1.09). At that time, 18 patients in the treatment group and 6 in the placebo group had an excellent outcome (risk ratio, 3.4; 95% CI, 1.3 to 8.9). CONCLUSIONS: This study suggests that magnesium reduces DCI and subsequent poor outcome, but the results are not yet definitive. A next step should be a phase III trial to confirm the beneficial effect of magnesium therapy, with poor outcome as primary outcom
Transforming growth factor-β1 regulates chemokine and complement production by human proximal tubular epithelial cells
Transforming growth factor-γ1 regulates chemokine and complement production by human proximal tubular epithelial cells. Previously it has been demonstrated that human proximal tubular epithelial cells (PTEC) are able to produce chemokines (such as IL-8 and MCP-1) and complement components (such as C2, C3, C4 and factor H), and that production of these proteins is regulated by pro-inflammatory cytokines such as interleukin-1α (IL-1α), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). Since TGF-γ is also expressed in the renal interstitium during inflammation, we investigated the effect of TGF-γ on the production of chemokines and complement components by PTEC in culture. Transforming growth factor-γ1 up-regulated IL-8 production by an average of 4.11 ± 1.0-fold. macrophage chemoattractant phagocyte (MCP-1) production, on the other hand, was down-regulated by TGF-γ1 by an average of 2.2 ± 0.7-fold. The production of C3 and C4 was also down-regulated after incubation with TGF-γ1 (1.9 ± 0.3- and 3.0 ± 1.2-fold, respectively). All effects were dose- and time-dependent and were found to be specific for TGF-γ1, as assessed by inhibition of the effect with a neutralizing antibody against TGF-γ1. These data, together with the knowledge that TGF-γ, chemokines and complement components play a role in several types of renal disease, suggest that TGF-γ is involved in the regulation of local expression of chemokines and complement components by tubular cells
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