Adsorption geometry and core excitation spectra of three phenylpropene isomers on Cu(111)

Theoretical C 1s near edge x-ray absorption fine structure (NEXAFS) spectra for the C(9)H(10) isomers trans-methylstyrene, alpha-methylstyrene, and allylbenzene in gas phase and adsorbed at Cu(111) surfaces have been obtained from density functional theory calculations where adsorbate geometries were determined by corresponding total energy optimizations. The three species show characteristic differences in widths and peak shapes of the lowest C 1s-->pi(*) transitions which are explained by different coupling of the pi-electron system of the C(6) ring with that of the side chain in the molecules as well as by the existence of nonequivalent carbon centers. The adsorbed molecules bind only weakly with the substrate which makes the use of theoretical NEXAFS spectra of the oriented free molecules meaningful for an interpretation of experimental angle-resolved NEXAFS spectra of the adsorbate systems obtained in this work. However, a detailed quantitative account of relative peak intensities requires theoretical angle-resolved NEXAFS spectra of the complete adsorbate systems which have been evaluated within the surface cluster approach. The comparison with experiment yields almost perfect agreement and confirms the reliability of the calculated equilibrium geometries of the adsorbates. This can help to explain observed differences in the catalytic epoxidation of the three molecules on Cu(111) based on purely geometric considerations.

Statistical analysis of GeneMark performance by cross-validation

We have explored the performance of the GeneMark gene identification method using cross-validation over learning samples of E. coli DNA sequences. The computations gave more accurate estimations of the error rates in comparison with previous results when a sample of non-coding regions was derived from GenBank sequences with many true coding regions unannotated. The error rate components have been classified and delineated. It was shown that the method performs differently on class I, II and III genes. The most frequent errors come from misinterpreting the coding potential of the complementary sequence in the same frame. The effects of stop-codons present in alternative frames were also studied to understand better the main factors contributing to GeneMark performance.

Spectroscopic analysis of small organic molecules: A comprehensive near-edge x-ray-absorption fine-structure study of C6-ring-containing molecules

We report high-resolution C 1s near-edge x-ray-absorption fine-structure (NEXAFS) spectra of the C6-ring-containing molecules benzene (C6H6), 1,3- and 1,4-cyclohexadiene (C6H8), cyclohexene (C6H10), cyclohexane (C6H12), styrene (C8H8), and ethylbenzene (C8H10) which allow us to examine the gradual development of delocalization of the corresponding pi electron systems. Due to the high experimental resolution, vibrational progressions can be partly resolved in the spectra. The experimental spectra are compared with theoretical NEXAFS spectra obtained from density-functional theory calculations where electronic final-state relaxation is accounted for. The comparison yields very good agreement between theoretical spectra and experimental results. In all cases, the spectra can be described by excitations to pi*- and sigma*-type final-state orbitals with valence character, while final-state orbitals of Rydberg character make only minor contributions. The lowest C 1s-->1pi* excitation energy is found to agree in the (experimental and theoretical) spectra of all molecules except for 1,3-cyclohexadiene (C6H8) where an energy smaller by about 0.6 eV is obtained. The theoretical analysis can explain this result by different binding properties of this molecule compared to the others.

[Brain natriuretic peptide for postoperative monitoring of the fluid balance in a cardiac surgery patient]

Brain natriuretic peptide is a neurohormone used for estimation of left ventricular wall tension and volume overload. We describe the use of this parameter in a postoperative cardiac surgery patient for detection and monitoring of left ventricular failure in a postoperative intensive care unit at a tertiary care center. Left ventricular failure was detected by brain natriuretic peptide levels, while x-ray and values obtained by the pulmonary artery catheter were inconclusive.

UV-induced skin changes due to regular use of commercial sunbeds

BACKGROUND/AIM

Increased pigmentation and thickening of the epidermis are the most important photoprotective skin reactions induced by ultraviolet (UV) radiation. The present study was designed to find out what changes are induced by regular use of commercial sunbeds twice weekly over a period of 6 weeks.

METHODS

The parameters analysed were skin pigmentation measured by chromametry, minimal erythema dose (MED) as a parameter of light sensitivity, epidermal thickening as determined by histology, induction of keratinocyte apoptosis as determined by TUNEL staining and antioxidant metabolism as measured by changes of cis- and trans-urocanic acid (UCA) content of the skin.

RESULTS

As expected, chromametry confirmed the clinically obvious increased skin pigmentation. However, no increase in MED was observed. In addition, neither epidermal thickening nor sunburn cells were seen. Significant detectable changes in proportion of the UCA isomer content of the UV-exposed skin were seen. The total UCA and cis-UCA content increased significantly between nearly all points of measurement. The amount of trans-UCA first decreased, then increased significantly between the different time points.

CONCLUSION

Our data indicate that sunbed-induced tanning is non-protective, which has to be addressed for persons looking for this effect before planning a stay in a sunny climate. However, sunbed-induced tanning may influence immunological reactions.

Oligodendrogliomas

PURPOSE

To study the pattern of contrast enhancement in MR and CT of oligodendrogliomas and to compare this with other imaging findings and with histopathological grading criteria.

MATERIAL AND METHODS

20 patients with oligodendrogliomas (12 low-grade WHO II and 8 anaplastic WHO III) were reviewed. 20 complete MR investigations, 20 non-enhanced CT studies and 16 CTs after contrast enhancement were estimated blindly without knowledge of the tumour histological grades.

RESULTS

All anaplastic oligodendrogliomas showed tumour contrast enhancement on MR and CT images. Also in 6/12 low-grade oligodendrogliomas the contrast was enhanced on MR imaging. In 5 of these, tumour calcifications were detected by CT. The remaining 6/12 WHO grade II cases showed no significant MR contrast enhancement. Of the oligodendrogliomas grade II, CT showed contrast uptake in 3 cases and no enhancement in 6, while in 3 cases postcontrast CT was not available. A comparison of contrast enhancement with tumour grade resulted in a p-value of 0.042 for MR and of 0.011 for CT. A combined statistical test of tumour grade and calcifications detected by CT compared with MR contrast enhancement showed a significant correlation (p=0.014).

CONCLUSION

These data demonstrated that a clear grading of oligodendrogliomas based on the image criterion MR contrast enhancement was not possible. We suppose that, besides tumour neovascularisation, additional factors such as calcifications may disturb the blood-brain barrier.

Immunocytochemical and biochemical identification of angiotensin II in human nasal tissue

Angiotensin II (ANG II) was identified immunocytochemically and biochemically in biopsy samples of human nasal tissue. Staining for ANG II was predominantly found in structures similar to a string of pearls with consecutive short varicose areas, which is characteristic for neuronal tissue. The localization of ANG II in neurons was confirmed by positive staining of adjacent tissue sections with a specific antibody to neurofilament or doublestaining with both antibodies in one section. Likewise, ANG II-like material was also determined radioimmunologically in nasal tissue extracts. The concentrations of ANG II varied form 1.28 to 332.78 fmol/g wet tissue weight with an average concentration of 79.61+/-44.09 fmol ANG II/g wet tissue weight (mean+/-SEM, n=7). The ANG II-immunoreactive material was further characterized biochemically by HPLC on a reversed phase C(18) column in an acetonitrile and methanol gradient as Ile(5)-ANG II and ANG II metabolites such as Ile(4)-ANG III, Ile(3)-ANG II(3-8)hexapeptide and Ile(2)-ANG II(4-8)pentapeptide.

The NIST Surface Structure Database -- SSD version 4

SSD-4, the fourth version of the NIST Surface Structure Database, has appeared in early 2002 as a significant upgrade to both the database and graphics software; it now also includes nearly 1300 structures published through the end of 2000. SSD is an interactive PC-based database of critically selected surface structures determined with a variety of experimental techniques. The data include not only atomic coordinates, bond lengths and bond angles, but also information about experimental preparation, measurement and analysis methods. The software provides advanced search and display facilities, as well as interactive three-dimensional color visualization and analysis tools of great flexibility. In addition, the program can generate publication-quality color or grayscale prints of any structure, with a host of user-selectable options (such as view angle, perspective, colors, ball and bond styles, and labels).

Comparison of the effects of two early intervention strategies on the health outcomes of malnourished hemodialysis patients

OBJECTIVE

To determine the efficacy and cost-effectiveness of providing oral supplementation early in the course of malnutrition for hemodialysis (HD) patients.

DESIGN

The study design consisted of 3 groups: an experimental group, a control group of patients with mild hypoalbuminemia (HA) (serum albumin [SA] = 3.5 to 3.7 g/dL), and a comparison group of patients with moderate to severe HA (SA = 2.5 to 3.4 g/dL).

SETTING

Ten outpatient hemodialysis centers in southeast lower Michigan.

PATIENTS

Treatment and control groups consisted of 32 HD patients with mild HA. Fourteen HD patients with moderate to severe HA comprised the comparison group.

INTERVENTION

The experimental group received diet counseling and oral supplementation, and the control group received diet counseling only. The comparison group received physician-prescribed oral supplements and dietary counseling to permit comparison of the experimental treatment with current supplementation practices.

MAIN OUTCOME MEASURES

Differences between groups in the number of patients reaching nutritional repletion, change in SA levels at the end of the study, and follow-up periods, were tested using chi-square analysis. Analysis of variance was used to compare group differences in treatment duration to repletion and number of hospitalization days.

RESULTS

During the study period, significantly more patients reached nutritional repletion in the experimental group and control group (50% and 57%, respectively) than in the comparison group (7%). Overall, repletion occurred more quickly in the experimental group (3.2 +/- 1.7 months) than in the control group (3.5 +/- 1.2 months), with a larger number of patients in the experimental group repleted by month 2 of the study phase. During follow-up, patients in the experimental group were far more likely to maintain nutritional repletion or continue to improve (61%) than patients in the control group (14%). Although too few patients were hospitalized to show statistical significance, there was a trend toward greater numbers of hospital days in more malnourished patients (208 days for the comparison group), followed by those with mild HA who did not receive oral supplements (107 days), and the experimental group (71 days).

CONCLUSION

Although the sample size for this study was too small for the results to be conclusive, it appears that use of nutritional supplements early in the course of malnutrition may provide benefits such as, attaining nutritional repletion more quickly, which results in less product usage. It is also more likely that good nutritional status will be maintained after supplementation is discontinued.

Immunohistochemical detection of simian immunodeficiency virus (SIV) in rectal mucosa of experimentally infected rhesus macaques (Macaca mulatta)

Experimental simian immunodeficiency virus (SIV) infection is the most appropriate animal model for human HIV infection. Eight male rhesus monkeys (Macaca mulatta) were intravenously or intrarectally infected with SIVmac251/MPBMC to comparatively investigate the distribution and spread of the virus within the rectum during the course of the disease. SIV-positive cells were immunohistochemically detected in rectal biopsies obtained at days 3 and 7 and week 2, 4 and 12 postinfection. SIV-expressing cells were detected for the first time at one week after experimental infection and were present in the lamina propria and lymph follicles. Numbers of positive cells per individual animal varied strongly in time, with a more rapid rise in animals with rapid progression of the disease. Differences were not observed between intravenous and intrarectal infection. Our observations support the significance of the intestinal tract as target organ in initial pathogenesis of SIV infection.

Analysis of histidine and urocanic acid isomers by reversed-phase high-performance liquid chromatography

The qualitative separation performance of a C18, C8 and C4 reversed-phase column was investigated for the separation of histidine and its metabolites histamine, 1-methyihistamine and trans- and cis-urocanic acid. Trans- and cis-urocanic acid were baseline separated from their precursor histidine on all three columns using isocratic elution with a mobile phase composed of 0.01 M aqueous TEAP pH 3.0 and acetonitrile at a ratio of 98:2 (v/v). However, histidine was not separated from histamine and 1-methyihistamine. Selecting the C8 column and introducing 0.005 M of the ion pairing reagent 1-octanesulfonic acid sodium salt into the aqueous solution and acetonitrile at a ratio of 90:10 (v/v), significantly improved the separation. The separation was also followed by a change in the retention times and the order of elution. The sequence of elution was histidine, cis-urocanic acid, trans-urocanic acid, histamine and 1-methylhistamine with retention times of 5.58 +/- 0.07, 7.03 +/- 0.15, 7.92 +/- 0.18, 18.77 +/- 0.24 and 20.79 +/- 0.21 min (mean +/- SD; n=5). The separation on the C8 column in the presence of the ion-pairing reagent was further improved with gradient elution that resulted in a reduction in the retention times and elution volumes of histamine and 1-methylhistamine. The detection limits of histidine and trans-urocanic acid at a wavelength of 210 nm and an injection volume of 0.05 ml were 5 x 10(-8) mol l(-1) (n=3). The kinetic of the in-vitro conversion of trans- into the cis-isomer after UV irradiation was depending on the time of exposure and the energy of the light source. UVB light induced a significantly faster conversion than UVA light. TUCA and cUCA samples kept at -25 degrees C were stable for up to 50 weeks. Samples, eluted from human skin showed various concentrations of histidine and trans- and cis-urocanic acid with an average of 1.69 +/- 0.33 x 10(-5) mol l(-1), 1.17 +/- 0.43 x 10(-5) mol l(-1) and 1.67 +/- 0.33 x 10(-5) mol l(-1), respectively (n=8).

Determination of histidine and urocanic acid isomers in the human skin by high-performance capillary electrophoresis

Histidine was baseline separated from histamine, 1-methylhistamine and cis- and trans-urocanic acid using high-performance capillary electrophoresis (HPCE) on a fused-silica column (50 cm x 75 microm) with 0.05 M NaH2PO4 buffer, pH 5.0, and 12 kV. The detection limit of histidine, trans- and cis-urocanic acid was 10(-6) M at a wavelength of 214 nm. The detection limit of the urocanic acid isomers was slightly enhanced to 5 x 10(-7) M at 267 nm. The transformation of the trans-urocanic acid standard in vitro into the cis-isomer was dependent on the time of exposure and the energy of the light source. UVB light induced a significantly faster conversion than UVA light. The HPCE method was used for the characterization and measurement of histidine and urocanic acid in human skin eluates. The concentrations of histidine, trans- or cis-urocanic acid in ethanol washes from the skin of healthy, non-allergic volunteers were 2.22+/-0.40 x 10(-5) 0.96+/-0.26 x 10(-5) and 1.04+/-0.30 x 10(-5) M, respectively, (mean+/-SEM, n=8). The results obtained by HPCE correlated well with data obtained by HPLC. Correlation coefficients of r2=0.981, r2=0.814 and r2=0.956 were found for histidine, trans- and cis-urocanic acid, respectively.

Mismatch repair deficiency in sporadic synchronous colorectal cancer

BACKGROUND

Hereditary non-polyposis colorectal cancer (HNPCC) patients frequently develop synchronous colorectal cancer (SCRC) which also occurs sporadically in other patients. Recent studies on microsatellite instability (MSI) in sporadic SCRC diverge completely in their findings (0%-100%). In the present study MSI and mismatch repair (MMR) proteins were evaluated according to standardised criteria (exclusion of a family history, MSI analysed according to NCI recommendations)

METHODS

Paraffin embedded sections of SCRC of 30 patients were evaluated for MSI and the loss of protein expression of hMLH1 and hMSH2.

RESULTS

3 out of 30 (10%) patients exhibited MSI-H which 5 out of 30 (17%) showed MSI-L. Loss of protein expression of either hMLH1 or hMSH2 was found in all cases of MSI-H and none of the MSI-L cancers.

CONCLUSION

MSI is found in sporadic cases of SCRC to about the same extent as it is mentioned in the literature on sporadic single colorectal cancers. Immunohistochemistry with mismatch repair proteins could be used as a pre-screening for MMR deficiency in sporadic SCRC.