Jostein Krane

Archaeal C80 isoprenoid tetraacids responsible for naphthenate deposition in crude oil processing

The structure of a novel class of octaterpene tetracarboxylic acids which is responsible for naphthenate deposition in crude oil processing has been determined by NMR and mass spectroscopy.

Intracellular manganese ions provide strong T1 relaxation in rat myocardium.

The efficacy of manganese ions (Mn2+) as intracellular (ic) contrast agents was assessed in rat myocardium. T1 and T2 and Mn content were measured in ventricular tissue excised from isolated perfused hearts in which a 5‐min wash‐in with 0, 30, 100, 300, or 1000 μM of Mn dipyridoxyl diphosphate (MnDPDP) was followed by a 15‐min wash‐out to remove extracellular (ec) Mn2+. An inversion recovery (IR) analysis at 20 MHz revealed two T1 components: an ic and short T1‐1 (650–251 ms), and an ec and longer T1‐2 (2712–1042 ms). Intensities were about 68% and 32%, respectively. Tissue Mn content correlated particularly well with ic R1‐1. A two‐site water‐exchange analysis of T1 data documented slow water exchange with ic and ec lifetimes of 11.3 s and 7.5 s, respectively, and no differences between apparent and intrinsic relaxation parameters. Ic relaxivity induced by Mn2+ ions in ic water was as high as 56 (s mM)−1, about 8 times and 36 times higher than with Mn2+ aqua ions and MnDPDP, respectively, in vitro. This value is as high as any reported to date for any synthetic protein‐bound metal chelate. The increased rotational correlation time (τR) between proton and electron (Mn2+) spins, and maintained inner‐sphere water access, might make ic Mn2+ ions and Mn2+‐ion‐releasing contrast media surprisingly effective for T1‐weighted imaging. Magn Reson Med 52:506–514, 2004.

Quantification of plasma lipids and apolipoproteins by use of proton NMR spectroscopy, multivariate and neural network analysis

New approaches for quantification of human blood plasma lipids and apolipoproteins are presented. One method is based on multivariate analysis of proton nuclear magnetic resonance spectra of human blood plasma. Although similar approaches have been developed previously, this is the first time principal component analysis (PCA) and partial least squares regression (PLS) have been applied to this particular task. Further, a large proportion of the subjects in this study were cancer patients undergoing treatment, which introduced a new dimension to the quantification of lipoprotein distributions. Calibration models for prediction of lipids and apolipoproteins were constructed by use of PLS, and blind samples were used to test the predictive ability. Comparison of the predicted vs observed data obtained by standard clinical chemical procedures gave good agreement; the correlation coefficient for total plasma triglyceride was 0.99, for total plasma cholesterol 0.98, for LDL cholesterol 0.97, and for HDL cholesterol 0.88. These results are comparable with those obtained with other methods. The quantitative analysis of 14 components (including total cholesterol and total triglyceride) of human blood plasma was also undertaken using various neural network (NN) analyses of selected portions of the spectra. Conventional fully connected backpropagation neural network topologies were capable of providing excellent predictions for the majority of the variables, confirming and reinforcing literature related to this approach. However HDL triglycerides were poorly predicted, while intermediate‐quality results were obtained for the LDL cholesterol, plasma apoA1 and LDL apoB variables. In these instances, applying significantly different neural network algorithms involving either general regression or polynomial neural networks in combination with genetic adaptive components for parameter optimisation made improved predictions. Copyright

Proton Nuclear Magnetic Resonance Spectroscopy of Plasma from Healthy Subjects and Patients with Cancer

To evaluate the ability of proton nuclear magnetic resonance (NMR) spectroscopy to indicate the presence or absence of malignant disease, we analyzed plasma samples from 104 patients with untreated cancer of various types and from 164 healthy controls. All specimens were coded with random numbers, and the investigators were blind to patient category. A statistically significant difference (P less than 0.001) was found between the mean (+/- SD) line widths in the plasma samples from the controls (39.1 +/- 6.7 Hz) and the line widths in plasma from the patients with cancer (35.2 +/- 6.4 Hz). However, the values showed considerable overlap between the two groups. The average line widths in the 54 male (36.0 +/- 7.9 Hz) and the 110 female (40.5 +/- 5.6 Hz) controls were significantly different (P less than 0.001). Differences in the average line width were also found between 34 male controls 40 years old or older (33.9 +/- 6.5 Hz) and 20 younger men (39.6 +/- 8.8 Hz) (P = 0.008) and between 61 female controls 40 or older (38.8 +/- 5.7 Hz) and 49 younger women (42.5 +/- 4.7 Hz) (P less than 0.001). The average line widths in 36 women with cancer (35.5 +/- 6.8 Hz) and their controls matched for age and sex (39.0 +/- 6.3 Hz) were significantly different (P = 0.03) but again showed much overlap. In 29 men with cancer, the line widths were not different from those of controls matched for age and sex. We conclude that proton NMR spectroscopy is not generally reliable for the detection of cancer. Furthermore, our data demonstrate the importance of studying control groups matched for age and sex.

NMR study and quantum mechanical calculations on the 2-[(2-aminoethyl)amino]-ethanol-H2O-CO2 system.

13C and 1H NMR spectra were obtained for AEEA (2-[(2-aminoethyl)amino]-ethanol)-H2O-CO2 systems and quantum mechanical calculations were carried out for the different AEEA species. The results suggest that the main AEEA species under the conditions studied are free amine, primary carbamate, and secondary carbamate. There is also some indication that a dicarbamate species is formed, this species does however only appear to be formed in small amounts. Comparison between experimental data and quantum mechanical calculations suggest that most AEEA species take on conforms with some degree of intramolecular hydrogen bonding.

Gyroxanthin—the First Allenic Acetylenic Carotenoid

Abstract Selected recent studies on marine allenic and acetylenic carotenoids are focused on. The structure elucidation of gyroxanthin, (3 S ,5 R ,6 S ,3′ S ,5′ R ,6′ R )-5,6-epoxy-6,7,7′,8′-tetradehydro-5,6,5′,6′-tetrahydro-β,β-carotene-3,19,3′,5′-tetrol, is reported in detail and in historical perspective. Gyroxanthin occurs as a diester (19-dodecanoate 3′-acetate) in the dinoflagellate Gymnodinium galatheanum .

Analysis of kerogens of miocene shales in a homogenous sedimentary column. A study of maturation using flash pyrolysis techniques and carbon-13 CP-MAS NMR

Abstract Type II/III kerogens from a sedimentary column of Miocene age were studied by pyrolysis-mass spectrometry, pyrolysis-gas chromatography and soli state carbon-13 CP-MAS NMR in order to follow the changes occurring in the kerogen as a result of maturation. An immature kerogen was artificially matured in the laboratory and the resulting material was compared with the mature natural samples. The three techniques used produced complementary information on the effect of maturation on the kerogen. The simulated maturation product was qualitatively similar to the most mature natural kerogen but the temperature has apparently been too high for a quantitative identical result. The Py-MS data showed an important increase in the abundance of simple sulphur products in the pyrolysate of the most mature samples.

The structure of abelsonite

Abelsonite, a C31 nickel-porphyrin of the deoxophylloerythroetioporphyrin type, is shown to have methyl groups in the 2, 3, 7, 12, and 18 positions and ethyl groups in the 8 and 17 positions by high-resolution, high-field 1H nuclear magnetic resonance and nuclear Overhauser effect studies. Removal of the nickel by treatment with methanesulfonic acid permitted confirmation of the structure on the free base porphyrin and demonstrated structural integrity under the conditions required for demetallation. The structure is best accounted for geochemically by the hypothesis that abelsonite is derived from a chlorophyll.

High-Resolution MAS 1H NMR Spectroscopic Analysis of Rabbit Cornea After Treatment with Dexamethasone and Exposure to UV-B Radiation

Metabolic changes in rabbit cornea after combined long-term steroid treatment and UV-B exposure were investigated. Corneas were exposed to UV-B radiation (2.05 J/cm2) after 36 days topical pretreatment with either 0.1% dexamethasone or saline. Twenty-four hours after UV-B exposure, corneas were excised and aqueous humour aspirated. Intact corneal tissues were analyzed by magic angle spinning proton NMR spectroscopy and pattern recognition methods. UV-B decreased corneal ascorbate (63% reduction), taurine (62%), and choline (63%), whereas glucose was elevated. Dexamethasone pretreatment further depleted corneal taurine and ascorbate, decreased aqueous ascorbate (85%), and accumulated glucose in cornea and aqueous humour. The results reflect antioxidative mechanisms and osmoregulation.

1,4,7,10-Tetrakis(2-hydroxyethyl)-1,4,7,10-tetra-azacyclododecane: a strong cation complexer

The title compound uses a varying number of side-arm ligating atoms for the complexation of alkali cation, leading to penta-, hepta-, and octa-co-ordination for Li+, Na+, and K+, respectively, and for tetrahedral encapsulation of a water molecule, while the conformation of the 12-membered ring remains the same.