Achieving 99.9% proton spin-flip efficiency at higher energy with a small RF dipole

We recently used a new ferrite rf dipole to study spin flipping of a 2.1 GeV/c vertically polarized proton beam stored in the COSY Cooler Synchrotron in Jülich, Germany. We swept the rf dipole's frequency through an rf-induced spin resonance to flip the beam's polarization direction. After determining the resonance's frequency, we varied the frequency range, frequency ramp time, and number of flips. At the rf dipole's maximum strength and optimum frequency range and ramp time, we measured a spin-flip efficiency of 99.92+/-0.04%. This result, along with a similar 0.49 GeV/c IUCF result, indicates that, due to the Lorentz invariance of an rf dipole's transverse integralBdl and the weak energy dependence of its spin-resonance strength, an only 35% stronger rf dipole should allow efficient spin flipping in the 100 GeV BNL RHIC Collider or even the 7 TeV CERN Large Hadron Collider.

Effects of pulsed electromagnetic fields on cognitive processes - a pilot study on pulsed field interference with cognitive regeneration

BACKGROUND

Due to the ubiquitous use of cellular phones much has been speculated on secondary effects of electromagnetic irradiation emitted by those. Additionally, several studies have reported vegetative alterations as well as effects on the neuronal and molecular levels in humans. Here, using a psycho-physiological test paradigm, we examined effects of exposure to pulsed electromagnetic fields on cognitive performance.

MATERIALS AND METHODS

In 11 volunteers, we tested cognitive processing under field exposure (GSM standard) and under field-free conditions. To examine the hypothesized effect of pulsed fields, we applied an auditory discrimination task and determined the participant's current 'Order Threshold' value. Following a first test cycle, the volunteers had to relax for 50 min while being, or not, exposed to pulsed electromagnetic fields. Subsequently, the test was repeated. Data acquired before and after the resting phase were compared from both experimental conditions.

RESULTS

We found that nine of the 11 test participants (81.8%) showed worse results in their auditory discrimination performance upon field exposure as compared with control conditions. Group data comparison revealed a statistical significance of P = 0.0105.

CONCLUSION

We could show that the participants' cognitive performance was impaired after exposure to pulsed electromagnetic fields. With regard to this finding, we recommend that the use of cellular phones should be restricted generally and in particular in respect of physical hazard of high-risk groups, e.g. elderly, children and ill people.

Is pro-matrix metalloproteinase-3 a marker for posttraumatic cartilage degradation?

OBJECTIVE

Since the development of posttraumatic osteoarthritis (OA) is a relatively slow process, estimation of OA risk would be of value with regard to chondroprotective measures and medication. In this study we investigated the significance of pro-matrixmetalloproteinase-3 (proMMP-3) for this purpose.

DESIGN

Synovial fluid (SF) and serum samples were collected from 259 patients of our trauma clinic at the time of arthroscopy. The extent of cartilage damage was assessed according to the Outerbridge-score. ProMMP-3 levels in SF and serum were determined by enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody. Additionally we determined SF and serum levels of total MMP-3 and COMP levels as well as TIMP-1 and -2 concentrations in 40 randomly selected patients by ELISA.

RESULTS

Serum proMMP-3 levels of the total cohort were markedly increased compared to healthy controls (P<0.007). The comparison of serum and SF lavage proMMP-3 concentrations showed a significant correlation (r(s)=0.41, P<0.0001), however, only 26% of the investigated samples were increased above normal ranges. The grade of cartilage damage did not correlate with enzyme concentration neither in patients' serum nor in SF samples. ProMMP-3 SF concentration was increased early after trauma. Furthermore, proMMP-3 correlated significantly with total MMP-3 serum and SF levels as well as COMP SF levels.

CONCLUSIONS

The measurement of proMMP-3 in serum or SF did not reflect the present cartilage damage and thus appears to have only minor potential for clinical use, but it should be considered for longitudinal studies, since it may reflect a risk for cartilage degradation in a subset of patients.

Measurement of spin-correlation parameters ANN, ASS, and ASL at 2.1 GeV in proton-proton elastic scattering

At the Cooler Synchrotron COSY/Jülich spin-correlation parameters in elastic proton-proton (pp) scattering have been measured with a 2.11 GeV polarized proton beam and a polarized hydrogen atomic beam target. We report results for A(NN), A(SS), and A(SL) for c.m. scattering angles between 30 degrees and 90 degrees. Our data on A(SS)--the first measurement of this observable above 800 MeV--clearly disagrees with predictions of available pp scattering phase-shift solutions while A(NN) and A(SL) are reproduced reasonably well. We show that in the direct reconstruction of the scattering amplitudes from the body of available pp elastic scattering data at 2.1 GeV the number of possible solutions is considerably reduced.

Kognitive Prozesse und dynamische Zeitstrukturen. Vorstellung eines Meßgerätes zur Untersuchung der Mikro-Vigilanz-Shift-(MVS-)Hypothese. Cognitive Processes and Dynamical Time Structures. Introduction of a Method for Testing the Microvigilance Shift (MVS) Hypothesis

The psychophysiological measuring method for the determination of the auditory order threshold (OT) is steadily gaining in importance, both for the diagnosis and treatment of speech disorders. Observed intraindividual variability of (macro-) vigilance led to the hypothesis of discontinuous cognitive processing in the central nervous system. The base for the variability of microvigilance is hypothesized to be in the phase difference of the alpha rhythm. To test for this hypothesis, we developed an EEG-comparator, which allows for a phase-dependent triggering of external stimuli. In direct comparison with stochastic (i.e. non-phase-dependent) stimulus presentation, the threshold in phase-dependent OT-testing is distinctly lower. Optimal results occurred at phase angels of phi = 90 degrees and phi = 270 degrees. Our findings support the hypothesis of a correlation between alpha rhythm and vigilance processes. Furthermore, there seems to be evidence that memory processes go with changes in vigilance, and in this context the alpha phase correlation seems to be important.

[Efficiency and safety of ACE-inhibiting imidapril in patients with essential hypertension]

In a survey including 2224 patients with essential hypertension we investigated efficacy and tolerability of the new ACE-inhibitor Imidapril. Mean blood pressure at baseline was 172 +/- 19/98 +/- 10 mmHg. Treatment with Imidapril 5-20 mg once daily caused a decrease in BP by 21 +/- 17/11 +/- 10 mmHg (p < 0.01/0.01). Systolic BP was reduced by > 15 mmHg in 71% diastolic BP by > 10 mmHg in 64% of patients. 29% of patients achieved the treatment goal of a blood pressure < or = 140/90 within an average of 26 days. Imidapril decreased pulse-pressure (one of the most important risk markers in hypertension) by 18% (74 +/- 17 to 61 +/- 11 mmHg, p < 0.01). ACE-inhibitor related adverse effects (cough, vertigo, headache, pruritus, tachycardia, orthostatic dysregulation or nausea) were observed in 38 patients (< 2%). Efficacy of treatment was graded by the physician in charge of the patient care by means of a questionnaire. Gradings were excellent or good in 96% of patients, moderate in 3% and poor in < 1%. In summary, the effects of Imidapril on blood pressure were comparable to those of other ACE-inhibitors. However, the frequency of adverse effects was low and similar to that of angiotensin-II-antagonists.

Dynamic association of trigger factor with protein substrates

Trigger factor is a ribosome-bound folding helper, which, apparently, combines two functions, chaperoning of nascent proteins and catalyzing prolyl isomerization in their folding. Immediate chaperone binding at the ribosome might interfere with rapid protein folding reactions, and we find that trigger factor indeed retards the in vitro folding of a protein with native prolyl isomers. The kinetic analysis of trigger factor binding to a refolding protein reveals that the adverse effects of trigger factor on conformational folding are minimized by rapid binding and release. The complex between trigger factor and a substrate protein is thus very short-lived, and fast-folding proteins can escape efficiently from an accidental interaction with trigger factor. Protein chains with incorrect prolyl isomers cannot complete folding and therefore can rebind for further rounds of catalysis. Unlike DnaK, trigger factor interacts with substrate proteins in a nucleotide-independent binding reaction, which seems to be optimized for high catalytic activity rather than for chaperone function. The synthetic lethality, observed when the genes for both DnaK and trigger factor are disrupted, might result from an indirect linkage. In the absence of trigger factor, folding is retarded and more aggregates form, which can neither be prevented nor disposed of when DnaK is lacking as well.

Coronary artery plaque burden and perioperative cardiac risk

BACKGROUND

Electron-beam computed tomography-derived coronary calcium score correlates with the morphologic severity of coronary artery disease, reflecting both global atherosclerotic plaque formation and coronary artery luminal narrowing. The current study examines the impact of coronary atherosclerotic plaque burden, measured by coronary calcium score, on the potential for perioperative myocardial cell injury, as assessed by cardiac troponin T elevations in patients undergoing elective vascular surgery. The authors further investigated whether perioperative myocardial cell injury in those patients adversely affects noninvasive measures of left ventricular systolic function, such as ejection fraction and wall motion score.

METHODS

Fifty-one consecutive patients scheduled for vascular surgery were enrolled in this prospective study. In addition to standard preoperative evaluation, including patient history and physical examination, electron-beam computed tomography scan, 12-lead electrocardiography, and transthoracic echocardiography were performed on the day before surgery. Subsequent evaluations on postoperative days 2 and 7 included transthoracic echocardiography and 12-lead electrocardiography. Cardiac troponin T determinations were performed on the day before surgery, immediately preoperatively, and on postoperative days 1, 2, 3, and 7.

RESULTS

The median coronary calcium score of the 51 patients was 997.0 (25th percentile, 202.5; 75th percentile, 1,949.5). Cardiac troponin T elevations exclusively occurred in patients with a coronary calcium score greater than 1,000. The six patients (12%) with perioperative cardiac troponin T elevations had a 2.5-fold higher coronary calcium score than those without cardiac troponin T elevation (P = 0.021). In these patients, the ejection fraction decreased from 61 +/- 10% to 52 +/- 13% (mean +/- SD) on postoperative day 2 and was 54 +/- 16% on postoperative day 7 (P = 0.022).

CONCLUSION

A high electron-beam computed tomography coronary calcium score, reflecting substantial coronary plaque burden, carries an increased risk for myocardial cell injury after vascular surgery. In these patients, myocardial damage may result in deterioration of global systolic left ventricular function.

Differing beta-blocking effects of carvedilol and metoprolol

BACKGROUND

Metoprolol is a beta(1)-selective beta-adrenergic antagonist while carvedilol is a non-selective beta-blocker with additional blockades of alpha(1)-adrenoceptors. Administration of metoprolol has been shown to cause up-regulation of beta-adrenoceptor density and to decrease nocturnal melatonin release, whereas carvedilol lacks these typical effects of beta-blocking drugs.

AIMS

To compare beta-blocking effects of metoprolol and carvedilol when applied orally in healthy subjects.

METHODS

We investigated the effects of single oral doses of clinically recommended amounts of metoprolol (50, 100 and 200 mg) and carvedilol (25, 50 and 100 mg) to those of a placebo in a randomised, double-blind, cross-over study in 12 healthy male volunteers. Two hours after oral administration of the drugs heart rate and blood pressure were measured at rest, after 10 min of exercise, and after 15 min of recovery.

RESULTS

Metoprolol tended to decrease heart rate during exercise (-21%, -25% and -24%) to a greater extent than carvedilol (-16%, -16% and -18%). At rest, increasing doses of metoprolol caused decreasing heart rates (62, 60 and 58 beats/min) whereas increasing doses of carvedilol caused increasing heart rates (62, 66 and 69 beats/min), 50 and 100 mg carvedilol failed to differ significantly from the placebo (71 beats/min).

CONCLUSIONS

We conclude that clinically recommended doses of carvedilol cause a clinically relevant beta-blockade in humans predominantly during exercise where it appears to be slightly (although not significantly) less effective than metoprolol. On the other hand, the effects of carvedilol on heart rate at rest appear rather weak, particularly in subjects with a low sympathetic tone. This might be caused by a reflex increase on sympathetic drive secondary to peripheral vasodilation resulting from the alpha-blocking effects of the drug. These results might be helpful in explaining why carvedilol, in contrast to metoprolol, may fail to cause up-regulation of beta-adrenoceptor density and does not decrease nocturnal melatonin release. This, in turn, may be a reason for the weak side-effects of carvedilol resulting from the beta-blockade. In addition, our data might be of interest in the interpretation of the forthcoming results of the COMET trial, although it has to be emphasised that they were derived from healthy subjects and, therefore, cannot be directly extrapolated to patients with heart failure.

Evaluation of right ventricular performance with a right ventricular ejection fraction thermodilution catheter and MRI in patients with pulmonary hypertension

STUDY OBJECTIVES

We sought to compare catheter studies using a right ventricular ejection fraction (REF) catheter together with echocardiography and MRI in patients with pulmonary hypertension.

PATIENTS AND METHODS

We compared hemodynamic findings, echocardiography, and MRI studies in 16 patients with pulmonary hypertension. Six healthy volunteers served as control subjects for the MRI studies.

RESULTS

MRI imaging provided accurate assessment of cardiac output in all but two patients. As compared with MRI, the REF catheter constantly underestimated the REF and overestimated right ventricular volumes in patients with pulmonary hypertension. REF, end-systolic and end-diastolic right ventricular volumes, and right ventricular muscle mass, as determined by MRI, were almost identical in patients with preserved cardiac function and those with low-output failure. The only factor that was different in both groups was the severity of tricuspid regurgitation.

CONCLUSION

Right ventricular dimensions and muscle mass do not differ in patients with pulmonary hypertension who have low cardiac output and those who do not. According to our results, the major determinant of cardiac output in these patients appears to be the severity of tricuspid regurgitation. The REF catheter provides invalid data on right ventricular dimensions in patients with pulmonary hypertension.

Paradoxical vestibular disease with trigeminal nerve-sheath tumor in a dog

A thirteen-year old spayed female poodle was referred because of atrophy of temporal and masseter muscles on the left and head tilt and episodical circling to the right side. Additionally, decreased facial sensation, absent menace reaction, palpebral and corneal reflexes on the left side, as well as ipsilateral hemiparesis and tongue palsy were noticed. Generalised vestibular ataxia and hypermetria in the front limbs were present. Based on the clinical signs, the presumptive anatomical localization of the lesion was the cerebellopontine angle including parts of the caudal brainstem with involvement of the trigeminal, facial and hypoglossal nerves. Involvement of either flocculonodular lobe or the caudal cerebellar peduncle on the left side causing paradoxical vestibular disease was suspected. On magnetic resonance imaging a large enhancing lesion in the area of the left cerebellopontine angle involving the trigeminal nerve and compressing cerebellum and brainstem was seen. Because of the poor prognosis the dog was euthanized on the owner's request. This space occupying lesion could be identified as a trigeminal neurofibrosarcoma/schwannoma on post mortem histopathological examination.

Stereoselective effects of (R)- and (S)-carvedilol in humans

Carvedilol is currently used as the racemic mixture, (R,S)-carvedilol, consisting of equal amounts of (R)-carvedilol, an alpha-blocker, and (S)-carvedilol, an alpha- and beta-blocker, which have never been tested in their optically pure forms in human subjects. We performed a randomized, double-blind, placebo-controlled, crossover study in 12 healthy male volunteers. Subjects received single oral doses of 25 mg (R,S)-carvedilol, 12.5 mg (R)-carvedilol, 12.5 mg (S)-carvedilol, and placebo at 8 AM as well as at 8 PM. Exercise was performed at 11 AM, and heart rate and blood pressure were measured at rest and after 10 min of exercise. Urine was collected between 10 AM and 6 PM, as well as between 10 PM and 6 AM, and the amounts of urinary 6-hydroxy-melatonin sulfate (aMT6s) were determined by RIA. Compared to placebo, (R)-carvedilol increased heart rate during exercise (+4%, P < 0.05) and recovery (+10%, P < 0.05); (S)-carvedilol decreased heart rate during exercise (-14%, P < 0.05) and recovery (-6%, P < 0.05), and systolic blood pressure during exercise (-12%, P < 0.05); (R,S)-carvedilol decreased heart rate during exercise (-11%, P < 0.05), and systolic blood pressure at rest (-7%, P < 0.05) and during exercise (-10%, P < 0.05). None of the agents had any significant effect on the release of aMT6s. Our results indicate that only (S)-carvedilol causes beta-blockade, whereas (R)-carvedilol appears to increase sympathetic tone, presumably as a physiological reaction to the decrease of blood pressure caused by alpha-blockade. None of the drugs had any influence on melatonin release. The weak clinical net effect of beta-blockade of (R,S)-carvedilol at rest might be one reason why this drug causes fewer side effects than other beta-blockers, such as a reduction of nocturnal melatonin release.

Left ventricular architecture after valve replacement due to critical aortic stenosis: an approach to dis-/qualify the myth of valve prosthesis-patient mismatch?

OBJECTIVES

Left ventricular hypertrophy in patients with critical aortic stenosis (AS) is an adaptive process that compensates for high intracavitary pressure and reduces systolic wall stress followed by an increase in myocardial masses. In the present prospective clinical trial, we investigated long-term compensatory changes in left ventricular geometry and function after aortic valve replacement using mechanical bileaflet prostheses with the main emphasis on the small-sized aortic annulus and valve prosthesis-patient mismatch.

METHODS

A total of 58 patients with critical AS were assigned to the following groups according to the predictive value of prosthetic valve area index (VAI): group EXMIS: 29 patients (VAI < or =0.99), expected mismatch; group NOMIS: 29 patients (VAI < or =0.99), no mismatch. At controls T(0) (before operation/operation (OP), T(1) and T(2) (4 and 20 months after OP) the left ventricular geometry was recorded by means of Imatron electron beam tomography and the transprosthetic velocities were measured by echocardiography.

RESULTS

Statistical analysis showed a consistent reduction in the absolute (P=0.04) and indexed (P=0.04) left ventricular myocardial mass for both cohorts; furthermore, there was a significant difference between EXMIS and NOMIS patients concerning the factors, time and mass reduction (P=0.005), because of distinct baselines. A logistic regression report revealed preoperative cardiac output, absolute left ventricular myocardial mass, perfusion, body surface area and the native valve orifice area as predicting coefficients and factors for a minimum mass reduction of 25%. We explain a mathematical formula that turned out to be the most sensitive for correctly classified factors.

CONCLUSIONS

The left ventricular geometry and transprosthetic velocities resulted in the same postoperative recovery for both EXMIS and NOMIS patients. The presented data showed that valve prosthesis-patient mismatch had no influence in several stepwise logistic regression models. We conclude that modern mechanical bileaflet prostheses allow both acceptable hemodynamics and recovery of left ventricular hypertrophy, even in small aortic annuli.

Thromboelastography for monitoring prolonged hypercoagulability after major abdominal surgery

Despite clinical and laboratory evidence of perioperative hypercoagulability, there are no consistent data evaluating the extent, duration, and specific contribution of platelets and procoagulatory proteins by in vitro testing. We tested the hypothesis that the parallel use of standard and abciximab-cytochalasin D-modified thromboelastography (TEG) can assess 7 days' postoperative hypercoagulability and can estimate the independent contribution of procoagulatory proteins and platelets. Thromboelastograms were performed before surgery, at the end of surgery, 6 h after surgery, and on postoperative days 1, 2, 3, and 7; they were analyzed for the reaction time and the maximal amplitude (MA). We calculated the elastic shear modulus of standard MA (G(t)) and modified MA (G(c)), which reflect total clot strength and procoagulatory protein component, respectively. The difference was an estimate of the platelet component (G(p)). There was a 10% perioperative increase of standard MA, corresponding to a 50% increase of G(t) (P < 0.0001) and an 86%-90% contribution of the calculated G(p) to G(t). We conclude that serial standard and modified thromboelastography may reveal prolonged postoperative hypercoagulability and the independent contribution of platelets and procoagulatory proteins to clot strength.

IMPLICATIONS

Postoperative hypercoagulability, occurring for at least 1 wk after major abdominal surgery, may be demonstrated by standard and modified thromboelastography. This hypercoagulability is not reflected by standard coagulation monitoring and seems to be predominantly caused by increased platelet reactivity.

Elliptic flow in Au+Au collisions at square root(S)NN = 130 GeV

Elliptic flow from nuclear collisions is a hadronic observable sensitive to the early stages of system evolution. We report first results on elliptic flow of charged particles at midrapidity in Au+Au collisions at square root(S)NN = 130 GeV using the STAR Time Projection Chamber at the Relativistic Heavy Ion Collider. The elliptic flow signal, v2, averaged over transverse momentum, reaches values of about 6% for relatively peripheral collisions and decreases for the more central collisions. This can be interpreted as the observation of a higher degree of thermalization than at lower collision energies. Pseudorapidity and transverse momentum dependence of elliptic flow are also presented.

[Is CNS activity modified by pulsed electromagnetic fields?]

In the present pilot study we examined the effects of electromagnetic fields on the biological organism. The study was prompted by discussions on the possible effects on the nervous system and cognitive processes of fields produced by mobile phones. The experiments were performed in an electrophysiological laboratory. Eleven volunteers were exposed to pulsed electromagnetic fields (GSM standard). The psychophysiological method of assessing the order threshold (Ordnungsschwelle = OS) was used to examine cognitive performance. Under the test conditions, nine of the subjects showed a loss of mental regeneration, as reflected by an increase in the OS, in comparison with the field-free situation. The results of our experiments suggest an influence of pulsed fields on the cognitive regeneration process.

Kinetics of CXCR4 and CCR5 up-regulation and human immunodeficiency virus expansion after antigenic stimulation of primary CD4(+) T lymphocytes

The chemokine receptors CCR5 and CXCR4 are coreceptors for the human immunodeficiency virus (HIV) and determine the cell tropism of different HIV strains. Previous studies on their regulation were performed under conditions of unspecific T-lymphocyte stimulation and provided conflicting results. To mimic physiologic conditions, highly purified primary Staphylococcus enterotoxin B (SEB)-reactive CD4 T lymphocytes were stimulated in the presence of autologous antigen-presenting cells and the kinetics of CCR5 and CXCR4 surface expression and HIV replication were studied. Both chemokine receptors were transiently up-regulated with maximal expression at day 3 after stimulation. The stimulated T cells were equally susceptible to productive infection with R5-and X4-tropic virus strains. Thus, antigenic stimulation of T cells promotes efficient replication of both, T cell-tropic and macrophage-tropic HIV. (Blood. 2000;96:1853-1856)

Excitation functions of the analyzing power in pp--> scattering from 0.45 to 2.5 GeV

Excitation functions A(N)(p(p),Theta(c.m.)) of the analyzing power in pp--> elastic scattering have been measured with a polarized atomic hydrogen target for projectile momenta p(p) between 1000 and 3300 MeV/ c. The experiment was performed for scattering angles 30 degrees </=Theta(c.m.)</=90 degrees using the recirculating beam of the proton storage ring COSY during acceleration. The resulting excitation functions and angular distributions of high internal consistency have significant impact on the recent phase shift solution SAID SP99, in particular, on the spin triplet phase shifts between 1000 and 1800 MeV, and demonstrate the limited predictive power of single-energy phase shift solutions at these energies.

Active recombinant human tyrosine kinase c-Yes: expression in baculovirus system, purification, comparison to c-Src, and inhibition by a c-Src inhibitor

C-Yes is a non-receptor-type tyrosine kinase of the Src family that is most closely related to c-Src. C-Yes has been implicated in development of some human cancers. Here we report on the expression, purification, and characterization of the active human recombinant c-Yes. A full-length human c-Yes clone has been generated and the protein was expressed in insect Sf9 cells. Active c-Yes was purified by liquid chromatography to yield a preparation with a high specific activity (160 nmol/min/mg using an optimal Src substrate peptide). In a comparison between human c-Yes and c-Src enzymes, relative phosphorylation efficiencies on nine protein and four peptide substrates were different. However, the recently described Src inhibitor CGP77675 inhibited human c-Yes with a potency similar to that of c-Src (IC(50) value of 6.5 nM). The purified preparation of active c-Yes provides a good basis for further enzymatic characterization and for the development of c-Yes-specific inhibitors.