Compound-specific δ13 C analysis of monosaccharides from soil extracts by high-performance liquid chromatography/isotope ratio mass spectrometry.

RATIONALE: Carbohydrates represent up to 25% of soil organic matter and derive from fresh plant input or organic matter transformation within the soil. Compound-specific isotope analysis (CSIA) of monosaccharides (sugars) extracted from soil provides a powerful tool to disentangle the dynamics of different carbohydrate pools of soils. The use of high-performance liquid chromatography/oxidation/isotope ratio mass spectrometry (HPLC/o/IRMS) allows isotope measurements without the need for derivatisation and thus increasing accuracy and precision of the isotopic measurement, compared with gas chromatography/combustion/isotope ratio mass spectrometry (GC/c/IRMS). METHODS: The CSIA of soil carbohydrates was performed using a HPLC/o/IRMS system. The chromatographic and mass spectrometric subunits were coupled with a LC-Isolink interface. Soil sugars were extracted after mild hydrolysis using 4 M trifluoroacetic acid (TFA). Chromatographic separation of the sugars was achieved using a low strength 0.25 mM NaOH solution as mobile phase at a flow rate of 250 µL min-1 at 10 °C. RESULTS: The chromatographic conditions allowed the baseline separation of the seven most abundant sugars in soil. Complete removal of TFA from the soil hydrolysate ensured chromatographic stability. The accuracy was better than 0.66 ‰ for amounts of >2.5 nM sugar on column. The sugars extracted from an agricultural soil appeared to be more enriched in 13 C than the soil organic carbon, and to have a similar isotopic signature to the soil microbial biomass. CONCLUSIONS: The proposed method proved to be suitable for the analysis of the common sugars in soil extracts and represents a precise tool for the study of carbohydrate dynamics. Copyright © 2013 John Wiley & Sons, Ltd.

Effects of fenofibrate on angiographically examined coronary atherosclerosis and left ventricular function in hypercholesterolemic patients.

Within the framework of a prospective lipid-lowering intervention study 44 patients were treated over a period of 3 years with a lipid-lowering diet and 200-400 mg fenofibrate daily. The intervention led to statistically significant decreases in total cholesterol (Chol), low density lipoprotein cholesterol (LDL-Chol) and triglycerides levels, and to a significant increase in high density lipoprotein cholesterol (HDL-Chol) levels. Despite intervention, in 8 patients the HDL-Chol levels decreased by up to 20 mg/dl, where these were mainly patients with high initial values. Likewise, the triglycerides of 4 patients whose initial levels were relatively low increased (up to 49 mg/dl) and the LDL-Chol levels of 8 patients whose initial levels were also low increased (up to 49 mg/dl). Only minor success was achieved through the 6-week diet, but this was still slightly significant for Chol and LDL-Chol levels. A total of 21 patients underwent repeat angiography within 3 years for clinical reasons. For the evaluation of the angiographic progress a total of 98 minor and moderate stenoses was measured using digital image processing and automatic contour finding. The change in the angiographic parameters 'percent diameter reduction' (%DR) and 'percent plaque area' (%PA) correlated with on-treatment LDL-Chol levels (%DR change with LDL-Chol: r = 0.67, P = 0.0005; %DR change with Chol: r = 0.61, P = 0.002; %PA change with LDL-Chol: r = 0.40, P = 0.037; %PA change with Chol: r = 0.38, P = 0.044), while for HDL-Chol and triglycerides no influence on the angiographic progress could be demonstrated. On the basis of the reproducibility of the measuring methods the patients were classified in the categories 'regression', 'unchanged' and 'progression'. The patients classified as 'regression' (parameter: %DR change) showed an LDL-Chol mean value of 162 +/- 9 mg/dl, whereas those classified as 'unchanged' or 'progression' showed values of 189 +/- 25 mg/dl and 199 +/- 21 mg/dl, respectively (P = 0.014). A negative correlation appeared between the angiographic progress parameters and the initial degree of stenosis. The left ventricular ejection fraction in the second angiography showed relationships to lipoprotein levels and angiographic progress parameters.

Treatment of unstable angina pectoris (European experience).

Unstable angina pectoris is used to describe accelerated angina, new onset of angina, or prolonged angina. The natural history of the angina varies according to clinical presentation. The 1-year mortality rate ranges from 2% to nearly 40%. Specific therapy includes nitrates, beta-adrenergic blockers, and/or calcium antagonists as well as antithrombotic therapy in the form of aspirin. Patients with severe angina at rest and ST- and T-wave changes should be admitted to a coronary care unit where full-dose heparin is administered. Coronary angiography should be performed in individuals who fail to respond to the conventional therapy in order to evaluate other therapeutic options, including percutaneous transluminal coronary angioplasty (PTCA) and coronary bypass surgery. In some cases, especially in patients with intracoronary thrombus, thrombolytic therapy may be beneficial.

Progression and regression of minor coronary arterial narrowings by quantitative angiography after fenofibrate therapy.

To study the effects of fenofibrate, a lipid-lowering medication, on patients with coronary artery disease, 191 minor coronary narrowings in 42 patients with coronary artery disease were analyzed by quantitative coronary angiography using computer-assisted contour detection. Computed parameters were percent diameter reduction and percent plaque area. A prospectively formed intervention group of 21 patients treated with special diet and fenofibrate (200 to 400 mg/day) was checked every 6 weeks with regard to risk factors. After a mean interval of 21 months, coronary angiography was repeated, using the same x-ray system and nearly identical projections. The intervention group was angiographically compared at follow-up with an untreated comparison group, also comprising 21 patients. Both groups had high initial serum cholesterol (mean 311 mg/dl) and low-density lipoprotein (LDL) cholesterol levels (mean 235 mg/dl). Only among the treated patients did lipid levels change significantly: cholesterol, -19%; LDL cholesterol, -20%; high-density lipoprotein cholesterol, +19%; and triglycerides, -30%. At angiographic follow-up, the changes in percent diameter reduction and percent plaque area correlated positively with the mean serum and LDL cholesterol levels of the intervention group. Significant differences were found in the change in percent plaque area between both groups. The intervention subgroup with angiographic regressions (11 patients) had significantly lower serum and LDL cholesterol levels than the intervention subgroup with angiographic progressions (10 patients). These results indicate the beneficial effect of fenofibrate on minor coronary narrowings. Because of its high reproducibility in measuring minor narrowings, quantitative coronary angiography proved to be a suitable method for angiographic follow-up.

Factors affecting the restenosis rate after percutaneous transluminal coronary angioplasty.

In an open study follow-up angiographies were performed independently from the clinical course on altogether 131 consecutive patients (99 men, 32 women) six months after percutaneous transluminal coronary angioplasty (PTCA). During this period patients received at least 320 mg of aspirin daily. Possible factors affecting the restenosis rate included age, sex, diabetes mellitus, arterial hypertension, abnormal lipid metabolism, smoking, dosage of aspirin administered, degree of stenosis shown by affected vessels before dilatation, number of vascular segments dilated and platelet reactivity. Restenosis was defined as a renewed narrowing of the dilated segment by 50% or more, with an increase in stenosis by at least 20%. In the present study the following restenosis rates were found six month after a primarily successful PTCA: 30% for the entire sample (39 out of 131 patients); 25% in patients with normal platelet function, 50% in those with mildly abnormal platelet function, and 60% in those with frankly abnormal platelet function; 24% in non-diabetic patients and 45% in diabetics. Analysis of the findings showed that abnormal platelet function and the presence of diabetes mellitus were the most important factors in the subsequent development of restenosis after angioplasty. The same also applied in a more restricted manner to the degree of stenosis present before angioplasty.

Influence of tree internal N status on uptake and translocation of C and N in beech: a dual 13C and 15N labeling approach.

Influence of plant internal nitrogen (N) stocks on carbon (C) and N uptake and allocation in 3-year-old beech (Fagus sylvatica L.) was studied in two 15N- and 13C-labeling experiments. In the first experiment, trees were grown in sand and received either no N nutrition (-N treatment) or 4 mM unlabeled N (+N treatment) for 1 year. The -N- and +N-pretreated trees were then supplied with 4 mM 15N and grown in a 13CO2 atmosphere for 24 weeks. In the second experiment, trees were pretreated with 4 mM 15N for 1 year and then supplied with unlabeled N for 24 weeks and the remobilization of stored 15N was monitored. On the whole-plant level, uptake of new C was significantly reduced in -N-pretreated trees; however, partitioning of new C was not altered, although there was a trend toward increased belowground respiration. The amount of N taken up was not influenced by N nutrition in the previous year. In +N-pretreated trees, partitioning of new N was dominated by the fine roots (59.7% at Week 12), whereas in -N-pretreated trees, partitioning of new N favored stem, coarse roots and fine roots (24, 21 and 31.9%, respectively, at Week 12), indicating the formation of N stores. The contribution of previous-year N to leaf N was about 15%. The N remobilized for leaf formation had been stored in stem and coarse roots. We conclude that, within a growing season, the growth of beech is strongly determined by the availability of tree internal N stores, whereas the current N supply is of less importance.

Effects of elevated carbon dioxide concentration on growth and N2 fixation of young Robinia pseudoacacia.

Effects of elevated CO2 concentration ([CO2]) on carbon (C) and nitrogen (N) uptake and N source partitioning (N2 fixation versus mineral soil N uptake) of 1-year-old Robinia pseudoacacia were determined in a dual 13C and 15N continuous labeling experiment. Seedlings were grown for 16 weeks in ambient (350 ppm) or elevated [CO2] (700 ppm) with 15NH4 15NO3 as the only mineral nitrogen source. Elevated [CO2] increased the fraction of new C in total C, but it did not alter C partitioning among plant compartments. Elevated [CO2] also increased the fraction of new N in total N and this was coupled with a shift in N source partitioning toward N2 fixation. Soil N uptake was unaffected by elevated [CO2], whereas N2 fixation was markedly increased by the elevated [CO2] treatment, mainly because of increased specific fixation (mg N mg(-1) nodule). As a result of increased N2 fixation, the C/N ratio of tree biomass tended to decrease in the elevated [CO2] treatment. Partitioning of N uptake among plant compartments was unaffected by elevated [CO2]. Total dry mass of root nodules doubled in response to elevated [CO2], but this effect was not significant because of the great variability of root nodule formation. Our results show that, in the N2-fixing R. pseudoacacia, increased C uptake in response to increased [CO2] is matched by increased N2 fixation, indicating that enhanced growth in elevated [CO2] might not be restricted by N limitations.

Nitrogen nutrition and water stress effects on leaf photosynthetic gas exchange and water use efficiency in winter wheat.

The responses of gas exchange and water use efficiency to nitrogen nutrition for winter wheat were investigated under well-watered and drought conditions. The photosynthetic gas exchange parameters of winter wheat are remarkably improved by water and nitrogen nutrition and the regulative capability of nitrogen nutrition is influenced by water status. The effects of nitrogen nutrition on photosynthetic characteristics and on the limited factors to photosynthesis are not identical under different water status. Intrinsic water use efficiency (WUE(i)) of the plants at the high-N nutrition was decreased by a larger value than that of the plants in the low-N treatment due to a larger decrease in photosynthetic rate than in transpiration rate. Carbon isotope composition of plant material (delta(p)) is increased by the increase of drought intensity. The delta(p) at a given level of C(i)/C(a) is reduced by nitrogen deficiency. Leaf carbon isotope discrimination (Delta) is increased by the increase of nitrogen nutrition and decreased by the increase of drought intensity. Transpirational water use efficiency (WUE(t)) is negatively correlated with Delta in both nitrogen supply treatments and increased with the nitrogen supply.

A dual 13C and 15N long-term labelling technique to investigate uptake and translocation of C and N in beech (Fagus sylvatica L.).

A continuous dual 13CO2 and 15NH4(15)NO3 labelling experimental set-up is presented that was used to investigate the C and N uptake and allocation within 3-year old beech (Fagus sylvatica L.) during one growing season. The C and N allocation pattern was determined after six, twelve and eighteen weeks of growth. The carbon uptake was distinctly different in the three phases examined: The first six weeks after budbreak were dedicated to leaf growth with a R/S (root to shoot) ratio of 0.14 for the new carbon. The second growth phase showed a balanced R/S ratio of C allocation and after week 13, the root compartment was the main carbon sink (R/S = 6.97). Nitrogen allocation was more basipetal as compared to carbon. In the second growth phase, R/S of Nnew was 5.57 but fell to 3.54 for the third growth phase probably due to formation of reserves in buds and stem.

Assessment of tree response to drought: validation of a methodology to identify and test proxies for monitoring past environmental changes in trees.

A thinning experiment stand at Avoca, Ballinvalley, on the east coast of the Republic of Ireland was used to test a developed methodology aimed at monitoring drought stress, based on the analysis of growth rings obtained by coring. The stand incorporated six plots representing three thinning regimes (light, moderate and heavy) and was planted in the spring of 1943 on a brown earth soil. Radial growth (early- and latewood) was measured for the purpose of this study. A multidisciplinary approach was used to assess historic tree response to climate: specifically, the application of statistical tools such as principal component and canonical correlation analysis to dendrochronology, stable isotopes, ring density proxy, blue reflectance and forest biometrics. Results showed that radial growth was a good proxy for monitoring changes to moisture deficit, while maximum density and blue reflectance were appropriate for assessing changes in accumulated temperature for the growing season. Rainfall also influenced radial growth changes but not significantly, and was a major factor in stable carbon and oxygen discrimination, mostly in the latewood formation phase. Stable oxygen isotope analysis was more accurate than radial growth analysis in drought detection, as it helped detect drought signals in both early- and latewood while radial growth analysis only detected the drought signal in earlywood. Many studies have shown that tree rings provide vital information for marking past climatic events. This work provides a methodology to better identify and understand how commonly measured tree proxies relate to environmental parameters, and can best be used to characterize and pinpoint drought events (variously described using parameters such as like moisture deficit, accumulated temperature, rainfall and potential evaporation).

Late pericardial tamponade after aortic and mitral valve replacement.

A report is presented on a patient who developed a pericardial tamponade on the 11th postoperative day after double valve replacement. Instead of classical signs of tamponade, however, the signs of posterior wall infarction were most prominent. The administration of nitrate resulted in deterioration of the circulatory situation, but the ST elevation in supraventricular tachycardia occurring from time to time regressed. As before the operation, coronary angiography showed normal conditions, and valve function was normal. The contrast-medium imaging of the right ventricle suggested a compression from ventral, and the right ventricular and right atrial pressures corresponded to a tamponade situation: in rethoracotomy, a blood coagulum roughly the size of a fist was found ventral to the right ventricle. After clearing the hematoma, there was an immediate improvement of the circulatory situation, and the ECG alterations regressed. Enzyme alterations in terms of myocardial infarction did not occur. We explained the symptoms as follows: The coagulum compressed the outflow tract of the right ventricle and thus caused on the one hand the hemodynamic situation of tamponade and on the other hand an extreme vagotonia with consecutive bradycardia and ST elevation.

[Excimer laser coronary angioplasty after primary unsuccessful PTCA]. / Excimer-Laser-Koronarangioplastie nach primär erfolgloser PTCA.

Excimer laser coronary angioplasty is a new technique for ablation of coronary stenosis, however, the indications for its application are still controversial. We describe two male patients, 60 and 65 years old, who underwent unsuccessful balloon PTCA with a short, concentric and calcified coronary stenosis, although balloon inflation pressure was increased to a maximum in both cases. Excimer laser angioplasty following the failed procedures showed no evidence for tissue ablation angiographically, but a repeat attempt with balloon angioplasty was successful in both cases. Thus, laser angioplasty may be considered as an adjunct technique to balloon angioplasty after a failed PTCA in resistant, non-inflatable lesions.

Noise reversion of a dual chamber pacemaker without noise.

Three patients are reported whose DDD pacemakers reverted to the asynchronous mode in the absence of skeletal muscle or electromagnetic (EMI) interference. In all three cases, the basic cardiac rhythm was atrial fibrillation with fast ventricular response due to intrinsic AV conduction. Noise reversion was triggered by the patients' own ventricular activity at cycle lengths shorter than the ventricular refractory period of the pulse generator. In one patient, asynchronous AV sequential pacing during atrial fibrillation was noted shortly after resuscitation from ventricular fibrillation; however, the initiation of the malignant ventricular arrhythmia by the pacemaker remains unproven. The mechanism of noise reversion by rapid cardiac activity and possible solutions to the problem by adequate pacemaker design are discussed.

[Isovolemic hemodilution in patients with coronary heart disease]. / Isovolämische Hämodilution bei Patienten mit koronarer Herzkrankheit.

In the age of cellsavers patients suffering from coronary heart disease are diluted to a hematocrit of 20% or even less during a surgical intervention in the coronaries and they leave the operating room with a hematocrit of 30%. On the other hand, a hemodilution to a level of 30% in patients with coronary heart disease represents a contraindication due to the limited coronary reserve. On the occasion of the collection of autologue blood, before vascular surgery or for therapeutical hemodilution, the hematocrit was reduced from 45 to 35% by means of an isovolemic hemodilution with 500 ml of Haes 200/0.5 10% in 50 patients. In the load-ECG the pressure X frequency-product and the dyspnoe decreased significantly. The microcirculation in the nailfold and the systemical blood fluidity increased significantly. As in 22% of the patients a deterioration was stated, we propose to dilute all the patients who have to undergo a coronary vessel operation without exclusion criteria once isovolemically and to stress them before and afterwards. The patients having a clinical defict should be diluted intraoperatively only to 30% and postoperatively not under 35%.

[Quantitative coronary angiography: progression and regression of coronary stenoses--an intervention study with fenofibrate]. / Quantitative Koronarangiographie: Progression und Regression von Koronarstenosen--Eine Interventionsstudie mit Fenofibrat.

In order to examine the effect of fenofibrate on coronary narrowings, within the framework of a prospective intervention study, we treated a total of 44 hypercholesterolemic patients (who were in our clinic to undergo PTCA) with diet and fenofibrate (200-400 mg/day) over a period of 3 years. After a mean interval of 21 months, control angiographies were performed in nearly identical projections for 21 patients on clinical grounds. The minor and medium-grade narrowings of the reangiographed patients at the beginning and at the end of the intervention interval were measured by means of digital image processing and automatic contour detection. The measuring parameters were percent diameter reduction (% DR) and percent plaque area (%PA). With regard to their angiographic progression, the 21 reangiographed patients of the intervention group were compared to a comparison group consisting likewise of 21 patients of similar age and sex distribution and persistently high lipid and lipoprotein levels. During the intervention period, the reangiographed patients of the intervention group showed the following changes of the lipid and lipoprotein levels in contrast to the outset values: cholesterol -19 +/- 8%, LDL -20 +/- 14%, HDL +19 +/- 44%, triglycerides -30 +/- 31%.(ABSTRACT TRUNCATED AT 250 WORDS)