Detection of human viral RNA via a combined fluorescence and SERS molecular beacon assay.

A dual-mode molecular beacon on a multiplexed substrate has been developed and applied to the measurement of unlabeled human viral RNA. The detection system is based on a combined surface-enhanced Raman scattering (SERS) and fluorescent molecular beacon assay that is assembled on Nanobarcodes™ particles. In this assay, a molecular beacon probe terminated with a fluorescent Raman label dye is conjugated to the metallic Nanobarcodes™ particles. The molecular beacon probe is a single-stranded oligonucleotide that has been designed with a hairpin structure that holds the dye at 3'-end close to the particle surface when the probe is attached through a 5'-thiol group. In this configuration, the SERS spectrum of the label was obtained and its fluorescence quenched because the dye is in very close proximity to a noble metal surface with nanoscale features (Nanobarcodes™ particles). The SERS signal decreased and the fluorescence signal increased when target viral RNA was captured by this molecular beacon probe. In addition, a hepatitis C virus reverse transcriptase-polymerase chain reaction (HCV RT-PCR) product was detected using this dual-mode beacon. The development of a multiplexed, label-free assay system with the reassurance offered by detection of two distinctly separate signals offers significant benefits for rapid molecular diagnostics.

Hospital outcome of acute myocardial infarction in patients with and without diabetes mellitus.

AIMS: To assess hospital mortality and morbidity in diabetic and non-diabetic patients with acute myocardial infarction and to compare the results between the two groups. METHODS: All patients admitted in 1999 to the intensive care unit of the Schwabing City Hospital with diagnosis of acute myocardial infarction were assessed for hospital mortality and co-morbidity. RESULTS: Three hundred and thirty patients with acute myocardial infarction were admitted. Of those, 126 (38%) were diabetic and 204 (62%) were non-diabetic patients. Mortality within 24 h after admission was 13.5% in diabetic patients and 5.4% in non-diabetic patients (P<0.01). Mortality during entire hospitalization was higher in diabetic than in non-diabetic patients (29.4% vs. 16.2%; P=0.004). Diabetic patients were resuscitated more frequently than non-diabetic patients (24% vs. 11%, P<0.01). In diabetic patients, heart rate at admission was increased (91 +/- 27 vs. 82 +/- 23/min; P<0.01) and presence of angina pectoris was reported less frequently (59% (n=72) vs. 82% (n=167); P<0.001). Preceding myocardial infarction, microalbuminuria, peripheral artery disease and arterial hypertension were more frequent in diabetic than in non-diabetic patients. Diabetic patients demonstrated higher C-reactive protein (CRP) levels than non-diabetic patients (91.4 +/- 78.2 mg/l vs. 45.2 +/- 62.4 mg/l; P<0.001). CONCLUSIONS: In diabetic patients with acute myocardial infarction, early hospital mortality is increased and signs of cardiac autonomic dysfunction and microangiopathy are detected more frequently than in non-diabetic patients. The need for advanced treatment strategies early in the course of diabetic patients with myocardial infarction is emphasized.

Conformational restraint in thermal rearrangements of a cyclobutane: 3,4-dicyanotricyclo[4.2.2.0(2,5)]decane.

There being no study of a cyclobutane so fused to another cyclic system that an antiperiplanar conformation of the related diradical be precluded, the system in the title has been synthesized and studied for its thermal behavior. In comparison to the thermal behavior of unconstrained 1,2-dicyanocyclobutane in stereomutation and fragmentation to acrylonitrile, the constrained system shows a approximately 10-fold higher ratio of stereomutation to fragmentation to the three cis-1,4-bis-beta-cyanovinylcyclohexanes. In these diolefins, a stereochemical correlation between the two olefinic fragmentation products is preserved. Revealed in the thermal rearrangement of isomer trans-1 is a surprising excess (78%) of cis-1-cis-beta-cyanovinyl-4-trans-beta-cyanovinylcyclohexane, cis,trans-2, the result of zero internal rotations within the diradical-in-caldera prior to fragmentation (retention of configuration). Similarly, to a comparably striking extent, anti,cis-1 gives trans,trans-2 as its major product (71%), again by zero internal rotations.

Fate of the intermediate diradicals in the caldera: stereochemistry of thermal stereomutations, (2 + 2) cycloreversions, and (2 + 4) ring-enlargements of cis- and trans-1-cyano-2-(E and Z)-propenyl-cis-3,4-dideuteriocyclobutanes.

This paper addresses the decades-old problem of gaining a measure of intellectual control over the fate of the diradical intermediate in not-obviously-concerted thermal rearrangements. It focuses mainly on the stereochemistry of the thermal rearrangement of cis- and trans-1-cyano-2-trans-propenylcyclobutane to the related ring-enlarged products, 4-cyano-3-methylcyclohexenes. The complete stereochemical profile is revealed by the incorporation of a pair of cis deuterons to serve as a stereochemical lighthouse. The striking result (besides providing a further example of the inapplicability of the orbital symmetry rules of Woodward and Hoffmann to not-obviously-concerted reactions) is the predominance of the same stereoisomer regardless whether starting from the cis or trans educt. This preference is rationalized by a simple conceptual scheme based on two premises of the behavior of the diradical as intermediate: removal of the diradical from the caldera of rotationally labile conformations occurs whenever the two radical centers come within bonding distance in an appropriate orientation of orbitals; relative internal rotational rates are in the order, cyanomethyl faster than methallyl, faster than internal rotation about the backbone.

Beyond butadiene II: thermal isomerization of the [2 + 2] photodimer of an all-trans tetraene, (R)-4,4abeta,5,6,10a-hexahydro-10abeta-methyl-2(3H)-methyleneanthracene, to a 16-membered [8 + 8] cycle.

Enthalpies of stabilization of polyenyl radicals of increasing order previously obtained by thermal geometrical isomerization are applied to the ethylene-cyclobutane paradigm. Progressively lower enthalpies of activation for thermal cyclodimerization and its reverse, cycloreversion, are predicted and realized. Photochemical dimerization at -75 degrees C of the optically pure tetraene of the title (1) at the semicyclic double bond produces in the main only one (4-axx) of the three allowed cyclobutanes (4), to which the tentative configuration anti-exo,exo is assigned. Equilibration among the three cyclobutanes (4), a slower rearrangement to a thermodynamically considerably more stable, [8 + 8] cyclohexadecahexaene (16), and a surprisingly slow fragmentation to 1 are studied kinetically between -42.3 and -8.2 degrees C. Cycloreversion of the dimer 16 to monomer 1 occurs in the range 60.4-86.6 degrees C (DeltaH = 31.7 kcal mol(-1), DeltaS = +10.8 cal mol(-1) K(-1)). The ratio of the rates of stereomutation and cycloreversion is significantly larger in these 1,2-dihexatrienylcyclobutanes than in two less strongly stabilized, previously published examples. The possible extension of Doubleday's calculational finding of entropic control of products from cyclobutane is considered.

Thermal reactions of anti- and syn-dispiro[5.0.5.2]tetradeca-1,8-dienes: stereomutation and fragmentation to 3-methylcyclohexenes. Entropy-dictated product ratios from diradical intermediates?

A series of cyclobutanes substituted 1,2- by polyenes of increasing radical-stabilizing power has been investigated to test the proposition that stabilization energies obtained independently from apposite, cis,trans geometric isomerizations can be successfully transferred to another system, in this paper, cyclobutanes. The first member of the series, 3-methylenecyclohexene (1), is photodimerized to anti- and syn-dispiro[5.0.5.2]tetradeca-1,8-dienes (anti-2 and syn-2), which undergo stereomutation (stereochemical interconversion) and cycloreversion (fragmentation) to 1 when heated in the range 72.1-118.2 degrees C: anti-2 --> syn-2, DeltaH() = 30.3 kcal mol(-)(1), DeltaS() = 0.2 cal mol(-)(1) K(-)(1); anti-2 --> 1, DeltaH() = 32.8 kcal mol(-)(1), DeltaS() = +8.0 cal mol(-)(1) K(-)(1). Agreement with an enthalpy of activation predicted by assuming full allylic stabilization in a hypothetical diradical intermediate is good. An example of further activation by a radical-stabilizing group is manifested by the approximately 20 000-fold acceleration in rate shown by the system 1-phenyl-3-methylenecyclohexene (3) and anti- and syn-2,9-diphenyldispiro[5.0.5.2]tetradeca-1,8-dienes (anti-4 and syn-4), measured, however, only at 43.6 degrees C. In both systems 2 and 4, volumes of activation for stereochemical interconversion and cycloreversion have been determined and found to be essentially identical within experimental uncertainties, DeltaV() = +10.2 +/- 1.0 and +12.6 +/- 1.4 cm(3) mol(-)(1), respectively (weighted means). These strongly positive values are consistent with the rate-determining step being the first bond-breaking, while the near identity of the volumes of activation argues against the indispensable second bond-breaking being a determining factor in fragmentation. These results are consistent with the theoretically based construct of Charles Doubleday for the paradigm, cyclobutane, in which the ratio between two channels of exit from a "generalized common biradical" is not controlled by enthalpy and entropy, as in the transition state model, but by entropy alone.

A sequential injection cold-vapor atomic absorption method for the determination of total mercury.

A sequential injection (SI) method for the determination of mercury via cold vapor atomic absorption spectrophotometry is presented. The method differs from flow injection (FI) cold vapor methods for the determination of mercury because of the simplicity of the system required for the method: one pump, one valve, a gas-liquid separator, and an atomic absorption spectrophotometer equipped with a quartz cell. Under optimal conditions, the method has the following figures of merit: a linear calibration range of 1.0 to 20 microg L(-1); a detection limit of 0.46 microg L(-1); and a precision of 0.90% RSD (8 microg L(-1)). The procedure allows for a sampling rate of one injection per 80 s (excluding sample pretreatment). Results from the determination of mercury in water and fish specimens are also presented. The figures of merit of the method are compared to two other SI methods for the determination of mercury.

Evaluation of noise reduction systems for cochlear implant users in different acoustic environment.

Evaluation of two different noise reduction algorithms for speech intelligibility enhancement in cochlear implant (CI) users is described in this report. The algorithms accomplish sophisticated interchannel processing of the noisy speech signals, picked up with two microphones, to form an improved monaural output signal, which is directly fed into the auxiliary input of the CI speech processor. Speech intelligibility tests were carried out in different realistic everyday life listening conditions to provide general and expressive performance assessment. Extensive tests in four CI users showed considerable speech intelligibility improvement using these noise reduction systems in adverse everyday life listening conditions.

Angiotensin-converting enzyme inhibitors in preventing remodeling and development of heart failure after acute myocardial infarction: results of the German multicenter study of the effects of captopril on cardiopulmonary exercise parameters (ECCE).

Early action of angiotensin-converting enzyme (ACE) inhibitors after myocardial infarction (MI) has been shown in large scale clinical trials to reduce mortality over the first weeks. However, the mechanisms involved are yet unclear and several trials showed a tendency toward a small, albeit unexpected, rise in cardiogenic shock or mortality. Since cardiopulmonary exercise testing (CPX) has become a "gold standard" in assessing the severity of heart failure, we studied--after finishing a pilot trial--the effect of captopril versus placebo in 208 patients who were individually titrated (titrated dose, mean 46/69 mg/day after 7 days/4 weeks, respectively) in order to preserve their blood pressure in the acute phase of myocardial infarction; we followed the development of congestive heart failure (CHF) over 4 weeks by measuring oxygen consumption. After 4 weeks, overall oxygen consumption at the anaerobic threshold (VO2-AT; 13.7 vs 13.1), maximal oxygen consumption (VO2max 19.3 vs 18.9 mL/kg per min) and exercise duration (896 vs 839 sec) showed a nonsignificant difference in favor of the captopril group. The predefined, categorized, combined endpoint of severe heart failure or death (heart failure necessitating ACE inhibition, VO2max < 10 mL/kg per min, or death) was significantly reduced in the captopril group (n = 7/104) versus placebo (n = 18/104; p = 0.03). Differences were mainly caused by fewer CHF events (delta n = 10). We conclude that ACE inhibition with individualized dose titration markedly reduces the 4-week incidence of severe heart failure or death; > 10 patients per 100 treated gained major benefits from this therapy.

Determinants of dual chamber pulse generators longevity.

The aim of this study was to investigate the effect of battery capacity, internal current drain, and stimulation energy on pulse generators longevity, and if battery impedance measurements can reliably predict pulse generators end-of-life. For this purpose, the records of 577 patients with a mean age of 65 +/- 14 years who had undergone implantation of two different dual chamber pulse generators (PG1: 409; PG2: 168) were retrospectively reviewed. Battery capacity were 2.3 Ah (PG1) and 3.0 Ah (PG2) while current drain at comparable nominal settings was 20 microA (PG1) and 30 microA (PG2) indicating a higher internal current drain of PG2. After a mean follow-up of 46 +/- 23 months, stimulation energy at reprogrammed output settings was significantly higher in PG1 as compared to PG2 (17.1 +/- 0.14) vs 15.5 +/- 0.24 J). Three PG1 (0.7%) and 12 PG2 (7.1%) (P < 0.01) had to be exchanged after a mean of 77.3 +/- 5.3 months (PG1) and 75 +/- 13.5 months (PG2) (P = NS) due to end-of-life being reached. The difference in battery impedances of PG1 and PG2 gained statistical significance 5 years after implantation (1.0 k omega vs 2.4 +/- 6.7 k omega) preceding the significant difference in PG survival after 6 years (98.7 +/- 1.3% vs 90.7 +/- 4.8%). These results indicate that internal current drain is the most important determinant of the pulse generators longevity and that battery impedance can reliably predict end-of-life. Therefore, the essential information about internal current drain should be available for each pacemaker, since it is required for adequate pulse generator selection. Diagnostic functions of dual chamber pulse generators should include measurements of battery impedance.

[Ergospirometry in the evaluation of cardiovascular drugs]. / Spiroergometrie in der Beurteilung kardiovaskulärer Pharmaka.

In the evaluation of drugs intended to alleviate symptomatology and to improve exercise capacity in congestive heart failure, various pathophysiologic mechanisms including impairment of cardiac output, oxygenation of blood, muscle blood flow, and muscle metabolism have to be considered. In various forms of acute and chronic heart failure these mechanisms contribute more or less to impaired oxygen uptake. In acute forms of heart failure pulmonary congestion and its effects on airway resistance and lung capacity might be the predominating mechanisms of symptoms, while in chronic heart failure impedement of muscle blood flow and metabolic changes, comparable with deconditioning, are additional pathomechanisms. The increase in cardiac output and in muscle blood flow provided by some positive inotropic agents and by vasodilators after acute administration is often paralleled by a decrease in arteriovenous oxygen difference and does not lead to an improvement of oxygen uptake. However, chronic therapy with some vasodilators can lead to improvement in oxygen uptake, either due to training effects or due to flow dependent or direct effects on muscle metabolism. In pulmonary congestion a decrease of elevated filling pressures can acutely lead to some improvement of exercise capacity. Furthermore, chronic decrease in filling pressures by administration of diuretics, nitrates, ACE-inhibitors or dopaminergic drugs leads to long-term improvement in oxygen uptake. By comparing hemodynamic effects of acute and chronic drug therapy in CHF with their effects on exercise capacity, the chronic decrease of filling pressures seems to be the major hemodynamic variable leading to improvement of exercise capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Experiences with ACE inhibitors early after acute myocardial infarction. Rationale and design of the German Multicenter Study on the Effects of Captopril on Cardiopulmonary Exercise parameters post myocardial infarction (ECCE).

Left ventricular damage by necrosis of myocardial tissue can lead to compromise of left ventricular function, to left ventricular volume increase and ultimately to development of heart failure. This sequence in the pathophysiology has been shown to be blunted by ACE inhibitors. Volume increase, however, can also be helpful in restoring stroke volume and ameliorate elevation of filling pressures. Furthermore, very early institution of ACE inhibition has failed to improve short-term mortality after myocardial infarction in one large trial. The aim of the ECCE trial therefore is, to investigate the early effects of the ACE inhibitor captopril on compromise of exercise capacity, thought to be a first measurable sign of developing heart failure. The ECCE trial is a randomized, seven-center investigation, studying the effects of ACE inhibition on oxygen uptake in a double blind, placebo controlled design in a group of 204 patients. Sample size was calculated on the basis of a pilot trial. The study design and first not unblinded data of 104 patients are presented. The population consists of predominantly male patients with mostly first myocardial infarction. They were admitted to hospital within five hours of onset of chest pain. End-diastolic volumes were normal, but ejection fraction was moderately compromised. ACE inhibition was started after the first day, but within 72 hours of onset of chest pain. After four and after twelve weeks, oxygen uptake was considerably below expected values and one third of the patients had severe compromise of exercise capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of converting enzyme inhibition on progression of chronic heart failure: results of the Munich Mild Heart Failure Trial.

OBJECTIVE: Neurohormonal activation has major impact on the pathophysiology of congestive heart failure. The Munich Mild Heart Failure Trial was designed to test the hypothesis that interference with the renin-angiotensin system by angiotensin converting enzyme inhibition favourably influences the natural history of heart failure. DESIGN AND PATIENTS: 170 patients, median New York Heart Association (NYHA) class II, were randomised to double blind treatment with 25 mg captopril twice a day or placebo in addition to standard treatment for a median observation period of 2.7 years. MAIN OUTCOME MEASURES: Progression of heart failure to NYHA class IV on an optimally adjusted standard treatment, death due to progressive heart failure, and sudden death. RESULTS: Heart failure progressed to class IV in nine patients (10.8%) treated with captopril and in 23 patients (26.4%) treated with placebo (p = 0.01). The mean survival time until this end point was 223 days longer in the captopril group (Kaplan-Meier life table analysis; p = 0.02). Also, progressive deterioration to severe heart failure was a powerful predictor of total mortality and death from heart failure; 80% of deaths due to progressive heart failure occurred after this end point. There were fewer deaths caused by progressive heart failure in the captopril group than in the placebo group (4 v 11; p = 0.10) but similar numbers of sudden deaths (11 v 10). Progressive heart failure was the cause of death in 18.2% of all deaths in the captopril group and 50% in the placebo group. Total heart failure events (the end point on which power calculation was based) were also more common in the placebo group (19 v 32 events) but not significantly so. Total mortality was similar to both groups (22 of 83 v 22 of 87). CONCLUSIONS: Angiotensin converting enzyme inhibition in conjunction with standard therapy early in the course of congestive heart failure slowed the progress of heart failure and thus favourably altered the natural history of the disease.

Mechanisms involved in cardiac enlargement and congestive heart failure development after acute myocardial infarction.

For 3 months, we followed up 40 patients with acute myocardial infarction, 20 were randomly assigned to treatment with captopril and 20 to placebo, to elucidate mechanisms inducing left ventricular volume enlargement and development of congestive heart failure. Echocardiographic follow-up could be obtained in 28 patients, 11 of whom showed more than a 10% increase in left ventricular systolic and/or diastolic volumes (captopril n = 3/15, placebo n = 8/13, p = 0.05). Volume increase was significantly associated with an impairment in exercise capacity (VO2 max in patients with vs. without volume enlargement 24.7 +/- 1.7 vs. 29.5 +/- 1.9 ml O2/kg/min; p < 0.05). Plasma renin activity, angiotensin II and catecholamines were normal in the acute and chronic postinfarction phase in patients on placebo as well as in patients 12-24 h after captopril intake. Plasma atrial natriuretic peptide concentration (ANP) was increased immediately after myocardial infarction, but ANP levels almost normalized in patients with captopril treatment, while they continued to be elevated in patients on placebo. The only technical parameter able to predict left ventricular volume increases was the sphericity index (28.7 vs. 35.7; p = 0.07). We concluded that morphologic deformation and filling pressures as estimated from elevated ANP levels are major factors promoting remodelling following myocardial infarction. ACE inhibitors might exert their favorable effect predominantly by reducing filling pressure.

Influence of severity of heart failure on the efficacy of angiotensin-converting enzyme inhibition.

Angiotensin-converting enzyme (ACE) inhibition slowed the progression of congestive heart failure (CHF) in 170 patients who were randomly assigned to either captopril or placebo in the Munich Mild Heart Failure Trial. The two major end points were progression from New York Heart Association (NYHA) functional classes I, II, or III to class IV, despite optimal, adjusted standard therapy, and death due to CHF. The relative risk for progressive CHF with captopril therapy was 0.34 (95% confidence interval = 0.17-0.68; p = 0.01). A total of 52 prerandomization variables were tested to determine their contribution to disease progression. Logistic regression analysis revealed 5 independent risk factors for progressive CHF: NYHA class, left ventricular end-systolic diameter, need for diuretic, age, and cardiothoracic ratio. The presence of greater than 2 of these risk factors increased the odds ratio for progression to 8.13 (p less than 0.001) compared with the presence of 0-2 risk factors. However, the effectiveness of captopril in preventing progression was higher within the subgroup of patients who had less severe CHF: the odds ratio was 0.12 (95% confidence interval = 0.03-0.45; p less than 0.01) for patients in NYHA class I or II on captopril and was 0.83 for those in class III. We conclude that the severity of CHF, as represented by the above-defined risk factors, is directly related to the likelihood for the development of progressive heart failure. However, the less severe the heart failure, the more effective the treatment with captopril will be in preventing disease progression. Thus, ACE inhibition has considerable potential for improving the prognosis of patients with mild heart failure.

[Prognosis of mild chronic heart failure: effects of the ACE inhibitor captopril]. / Prognose bei leichter chronischer Herzinsuffizienz: Einflüsse des ACE-Hemmers Captopril.

UNLABELLED: The Munich Mild Heart Failure Trial (MHFT) investigated the influences of ACE-inhibition on progression of congestive heart failure (CHF). Major end points were progression of CHF from New York Heart Association (NYHA) functional classes I to III to NYHA functional class IV despite optimal adjusted standard therapy and death due to congestive heart failure, i.e. death due to pump failure or sudden death. 170 patients were randomly assigned to treatment with either captopril (n = 83) 25 mg b.i.d. or placebo in addition to standard therapy for a median observation period of 2.7 years. The major result of this trial was the decrease in the relative risk for progressive heart failure by captopril therapy to 34% (95% confidence interval 17 to 68%; p = 0.01). Though total mortality was not reduced, death due to pump failure was found considerably less often on captopril than on placebo (18.2 vs 50% of total deaths in each group). In addition this report describes influences of captopril therapy on left ventricular size and function, heart size on X-ray, influences on symptomatology, electrolytes, ventricular arrhythmias, on concomitant therapy as well as effects in various subgroups. The major finding of the trial--the influence on progression of CHF--was independent of the underlying cardiac disease and was consistent in subgroups with different etiology of heart failure. Captopril blunted the increase in norepinephrine levels usually seen with increasing severity of congestive heart failure. There was a significant increase in serum sodium and potassium levels in the captopril treated group. Left ventricular size and function were well preserved in the patients still on randomized therapy after two years. No effects of therapy on ventricular ectopic activity were found in a subgroup of 93 patients that had had Holter monitoring. IN CONCLUSION: Captopril has marked effects on progression of disease and reduces the likelihood of progressive heart failure in patients with mild symptoms. Several indices of unfavourable prognosis are either improved (sodium, norepinephrine, angiotensin II) or stabilized (left ventricular function). Thus ACE-inhibitors are to be considered for all patients requiring medical therapy for congestive heart failure.