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Biomedical subjects

R Vogt

Publications and source records attributed to R Vogt.

At least 19 recordsLinked to original sources
PubMed2005

Nucleation particles in diesel exhaust: composition inferred from in situ mass spectrometric analysis.

Mass spectrometric measurements of size and composition of diesel exhaust particles have been performed under various conditions: chassis dynamometer tests, field measurements near a German motorway, and individual car chasing. Nucleation particles consisting of volatile sulfate and organic material could be detected both at the chassis dynamometer test facility and during individual car chasing. We found evidence that if nucleation occurs, sulfuric acid/water is the nucleating agent. Low-volatile organics species condense only on the preexisting sulfuric acid/water clusters. Nucleation was found to depend strongly on various parameters such as exhaust dilution conditions, fuel sulfur content, and engine load. The latter determines the fraction of the fuel sulfur that is converted to sulfuric acid. The organic compounds (volatile and low-volatile) condense only on preexisting particles, such as both sulfuric acid nucleation particles and larger accumulation mode soot particles. On the latter, sulfuric acid also condenses, if the conditions for nucleation are not given. The overall ratio of sulfate to organic (volatile and low-volatile) is also strongly dependent on the engine load. It was found that the production of nucleation particles even at high engine load can be suppressed by using low-sulfur fuel.

Air Pollutants↗
PubMed2005

[Usability of self-tonometry under ambulatory conditions to obtain daily profiles of intraocular pressure at home].

BACKGROUND: Diurnal profiles of intraocular pressure at opening times in the doctor's office do not deliver enough information, especially nightly and early morning measurements are lacking. Self-tonometry using the automatic self-tonometer "Ocuton S" might be suitable to achieve valid 24-hour IOP profiles without the need to stay in a hospital. MATERIALS AND METHODS: 96 people were taught to use the automatic self-tonometer once. Those who had learnt self-tonometry after this training underwent a diurnal IOP profile for 24 hours in the hospital using Goldmann tonometry and self-tonometry every 4 hours at the same times of day. One to three days later, they created a third IOP profile at home using self-tonometry at the same intervals as at the hospital. The IOP profiles were then tested for equality. RESULTS: 50 people out of 96 were able to perform self-tonometry after one training session. The IOP measurements of all three IOP profiles did not differ by more than 2 mmHg and thus may be considered comparable. There was no significant difference between daily curves, either. CONCLUSIONS: Self-tonometry using the automatic self-tonometer "Ocuton S" appears to be suitable to record diurnal profiles of intraocular pressure at home.

Adult↗
PubMed2003

Inhomogeneous shadowing effects on J/psi production in dA collisions.

We study the effect of spatially homogeneous and inhomogeneous shadowing on J/psi production in deuterium-nucleus collisions. We discuss how the shadowing and its spatial dependence can be measured by comparing central and peripheral dA collisions. These event classes may be selected by using gray protons from heavy ion breakup and events where the proton or neutron in the deuterium does not interact. We find that inhomogeneous shadowing has a significant effect on central dA collisions, larger than expected in central AA collisions. Results are presented for dAu collisions at sqrt[s(NN)]=200 GeV and dPb collisions at sqrt[s(NN)]=6.2 TeV.

Journal Article↗
PubMed2003

Isomer specific synthesis using the Suzuki-coupling. Polychlorinated terphenyls as standards for environmental analysis.

Defined polychlorinated terphenyl (PCT) single congeners as reference standards are the prerequisite for the development of analytical methods for their determination and quantification in the environment. The selective synthesis of PCTs for environmental analytical purposes by application of the Suzuki-coupling reaction is described. Under easily modified standard reaction conditions of this coupling process the PCTs can be obtained by reaction of benzeneboronic acids with dibromobenzenes mostly in good yields, as described by the synthesis of following PCT congeners: p-PCT (3,3("),5,5(")-tetrachloro-, 2,2("),4,4(")-tetrachloro-, 2('),3,3("),5,5(")-pentachloro-); m-PCT (3,3("),5,5(")-tetrachloro-) and o-PCT (3,3("),5,5(")-tetrachloro-). The terphenyl congeners were characterized by NMR (1H, 13C)- and FT-IR-spectroscopy. Their purity was checked by GC/MS analysis. The experimental and quantum-chemically calculated FT-IR-spectra were compared and it was shown, that the determination of the chlorine substitution pattern in the terphenyl congeners by their typical absorption spectra is possible.

Environmental Monitoring↗
PubMed2002

Investigation into a cluster of infant deaths following immunization: evidence for methanol intoxication.

A cluster of infant deaths due to severe metabolic acidosis following immunization was reported in a prosperous farming village in Egypt. Fears that more deaths might occur, and of a deleterious effect on national immunization programs prompted an urgent investigation by national and international partners. The deaths, and other previously unrecognized illness following immunization, were associated with excessive topical application of methanol. Methanol was employed as an anti-pyretic and anti-inflammatory agent following injections. Fear of adverse reactions to vaccine had encouraged increasing use of methanol for these purposes. Local physicians and nurses were unaware of the toxicity of methanol and did not consider it in the differential diagnosis, and thus did not offer appropriate life-saving therapy. The interaction of traditional practices and modern medical interventions can have clinically important consequences, and should be considered when programs are introduced and as they are monitored.

Cohort Studies↗
PubMed2001

[Shiitake dermatitis: flagellate dermatitis after eating mushrooms].

The name of flagellate dermatitis originates from self-flagellating medieval people. This dermatitis is not rare as a drug eruption following bleomycin therapy. An identical skin eruption caused by the mushroom shiitake Lentinus edodes is more common but reported mostly from Japan. We saw a 67-year-old patient who presented with the typical linear scratch marks after a dinner in a Chinese restaurant. The basic mechanism is a toxic epidermal damage. Since it is not clear why the dermatitis does not occur frequently since Shiitake is the second most popular mushroom in the world, we discuss possible cofactors that may trigger the toxic reaction.

Administration, Oral↗
PubMed2000

[Basic tenets for quality circles in North Rhine Medical Service of Public Health Insurance].

The Medical Advisory Service of the Health Insurance in the area of the Northern Rhine (MDK Nordrhein) has set up an internal concept for quality management since 1998. This concept includes the installation and performance of quality circles. Staff members were internally qualified as "presenters". They worked out principles for quality circles of the MDK North Rhine which were implemented as binding basic rules by the managing conference of the MDK. The principles will be presented in detail.

Germany↗
PubMed1999

The effect of buthionine sulfoximine on the growth of Leishmania donovani in culture.

Changes in composition of the principal low molecular mass thiols of Leishmania donovani were monitored during the transformation of promastigotes, first to stationary phase metacyclic forms and then to amastigotes. No consistent variation in the thiol composition of the parasite which could account for the known increase in resistance of metacyclic and amastigote lifecycle forms to oxidant stress could be established. Amastigotes cultivated at 37 degrees C also produced ovothiol A, as judged by incorporation of radiolabel from [3-methyl]methionine and [14C]histidine, and the incorporation of radiolabel from [35S]cysteine into ovothiol A represented about 10-15% of the total label recovered in ovothiol A, glutathione and trypanothione. Amastigotes were less susceptible than promastigotes to the effects of the redox cyclers paraquat and menadione and grew in culture in the presence of up to 20 mM buthionine sulfoximine, which completely blocked the synthesis of glutathione and its spermidine conjugates. Glutathione and trypanothione biosynthesis is, therefore, not necessary for the replication of L. donovani amastigotes in culture. Inhibition of the formation of glutathione and trypanothione did not result in an upregulation of ovothiol A production.

Animals↗
PubMed1999

Purification and characterization of the lysozyme from the gut of the soft tick Ornithodoros moubata.

The gut of the adult soft ticks Ornithodoros moubata displays high lytic activity against the bacteria Micrococcus luteus. The activity differed in the range of two orders of magnitude among individual animals and increased on average 4 fold during the first week following ingestion. In homogenates of first instar nymphs the activity was much lower increasing exponentially as nymphs neared the first molt. The protein responsible for this activity was purified out of gut contents of adult ticks by means of affinity adsorption on magnetic-chitin followed by two chromatography steps on cation exchange FPLC column MonoS. The homogeneous active protein has a mass of 14006 +/- 20 Daltons as determined by MALDI-TOF mass spectrometry. The N-terminal amino-acid sequence of this protein is K-V-Y-D-R-C-S-L-A-S-E-L-R with the highest similarity to the lysozyme from liver of rainbow trout and to lysozymes from digestive tracts of several mammals. The motif DRCSLA is specific for the digestive lysozymes of several dipteran insects. Based on this evidence, we have identified the protein as the tick gut lysozyme. The tick gut lysozyme has a pI near 9.7 and retains its full activity after treatment at 60 degrees C for 30 minutes. The pH optimum of the tick lysozyme was in the range from pH 5-7. Only marginal activity could be detected at pH > 8 which raises the question about the function of lysozyme in anti-bacterial defense in the environment of the tick gut.

Amino Acid Sequence↗
PubMed1998

Quantitative flow cytometry: inter-laboratory variation.

Quantitative flow cytometry (QFCM) offers a means of standardization within and between flow cytometers. QFCM parameters were set by determining the antibody-binding capacity (ABC) of CD4, CD8, and CD3 cells from 10 normal donors with the use of eight FACScan flow cytometers. QC3 beads and a certified blank bead were used to set up the instruments. Fluorescein isothiocyanate (FITC) conjugated to molecular equivalents of soluble fluorochrome (MESF) microbead standards was used before and after the donor samples were run to ensure that the machines were operating consistently. Lyophilized cells (Cytotrol) were used as a target, to control for antigen expression in the cell preparation. Quantitative Simply Cellular (QSC) beads were used to establish a standard calibration curve for each of the FITC and phycoerythrin antibody conjugates on each of the instruments. Single-parameter fluorescent histograms derived from list-mode files were used to calculate the slope (coefficient of response), intercept (zero channel), number of channels per decade, and ABC or MESF threshold (blank bead). The fluorescence intensity (geometric mean) of the positive and negative donor cell populations was compared with the standard curves, and the ABCs were calculated. The results show consistent instrument performance between laboratories. However, after standardization of CD3, CD4, and CD8 ABCs to microbeads, large variations were noted between donors and laboratories. The source of this variation does not appear to be in the instrumentation but may be due to the lack of an unified set-up protocol, introducing issues of antibody saturation, methods for whole blood lysis and fixation, and the behavior of the microbead standards.

Flow Cytometry↗
PubMed1998

Pantoprazole 20 mg is effective for relief of symptoms and healing of lesions in mild reflux oesophagitis.

AIM: To investigate the efficacy of a low dose of pantoprazole, a gastric proton pump inhibitor, for the relief of symptoms and healing of lesions in mild gastro-oesophageal reflux disease (GERD), and to compare it with the efficacy of ranitidine. METHODS: Patients with endoscopically established GERD (Stage I, Savary-Miller classification) were enrolled into a randomized, double-blind, parallel-group and multicentre study (intention-to-treat n = 209, age range 19-82 years). They were treated once daily with oral pantoprazole 20 mg or ranitidine 300 mg, for up to 8 weeks. End-point parameters included relief of symptoms (heartburn, acid regurgitation, pain on swallowing) and the healing of GERD lesions. Relief from symptoms was assessed after 2 and 4 weeks, and endoscopically confirmed healing of lesions after 4 and 8 weeks. RESULTS: The proportion of patients reporting complete relief from symptoms after 2 weeks was greater in the pantoprazole than in the ranitidine group (69 vs. 48%, P < 0.01), with further improvements seen in the pantoprazole group after 4 weeks (80 vs. 65%, P < 0.05, Cochran-Mantel/Haenszel test). Healing of lesions was confirmed in 70/87 (80%) patients after 4 weeks (pantoprazole group), as compared with 55/86 (64%) patients (ranitidine group) (P < 0.05, per protocol population); after 8 weeks the respective results were 78/87 (90%) and 63/86 (73%) patients (P < 0.01). Both study medications were well tolerated. CONCLUSION: Low-dose pantoprazole (20 mg) is clinically superior to ranitidine (300 mg) in providing fast relief from symptoms and healing of lesions in patients with mild GERD.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1998

Immunological markers among workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

OBJECTIVES: To examine the association of immune cell number and function with occupational exposure to substances contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). METHODS: A cross sectional medical survey. The exposed participants were employed at two chemical plants between 1951 and 1972 in the manufacture of 2,4,5-trichlorophenate and its derivatives. The reference group consisted of people with no occupational exposure to phenoxy herbicides who lived within the communities of the workers. Data from a total of 259 workers and 243 unexposed referents were included in the analysis of immune function. Laboratory tests for immune status included enumeration of circulating leukocyte and lymphocyte populations, proliferative responses of circulating lymphocytes to mitogens and antigens, and serum concentrations of the major immunoglobulins and complement factor C3. RESULTS: The workers had substantial exposure to substances contaminated with TCDD, as indicated by a lipid adjusted mean serum TCDD concentration of 229 ppt compared with a mean of 6 ppt in the unexposed referents. Workers were divided into categories based on their serum TCDD concentration. For all categories except the lowest, with values of serum TCDD comparable with the unexposed referents, there were increased odds of having lower counts of CD26 cells (activated T cells) (odds ratio (OR) 1.0, 95% confidence interval (95% CI) 0.5 to 1.8 for TCDD < 20 ppt; OR 1.6, 95% CI 0.8 to 3.2 for TCDD 20-51 ppt; OR 2.7, 95% CI 1.4 to 5.1 for TCDD 52-125 ppt; OR 2.6, 95% CI 1.4 to 4.9 for TCDD 125-297 ppt; OR 2.4, 95% CI 1.3 to 4.6 for TCDD 298-3389 ppt). A less consistent finding was decreased spontaneous proliferation of cultured lymphocytes. However, increases were found in proliferation of lymphocytes in response to concanavalin and pokeweed in workers in the high TCDD category. Age, cigarette smoking, and alcohol were significant predictors of several immunological outcomes. CONCLUSIONS: Associations between serum TCDD concentration and both a decrease in circulating CD26 cells and decreased spontaneous background proliferation were the major findings of this study. These results are unlikely to be of clinical importance but may reflect limited evidence for an association between immunological changes in workers and high serum concentrations of TCDD, or chance findings resulting from the evaluation of multiple immunological variables.

Adult↗
PubMed1996

Standardizing flow cytometry: construction of a standardized fluorescence calibration plot using matching spectral calibrators.

Calibration of flow cytometers is becoming an increasingly important issue for both quality control of instrument performance and quantitation of antibody binding capacity of cells. Due to the numerous different instruments and analysis software currently available, a standardized method of calibration is necessary if interlaboratory comparison of instrument performance and antibody binding is to be achieved. This report describes a new methodology to obtain a standard calibration plot that can be derived from all instruments and from which specific instrument-independent performance parameters may be calculated that can be used to directly compare the performance and setup of these instruments. The requirements that the calibrated standards must meet are discussed, as well as the acceptable ranges proposed for the instrument-independent performance parameters. In addition, data are presented from standard calibration plots generated by different flow cytometers in numerous laboratories. The corresponding Primary Performance Parameters calculated from these plots are presented and compared. It is expected that the use of this calibration method may help standardize flow cytometric measurements and will provide instrument-independent performance parameters to monitor quality control of instruments and reagents.

Calibration↗
PubMed1996

An N-terminal partial sequence of the 13 kDa Pycnopodia helianthoides sperm chemoattractant 'startrak' possesses sperm-attracting activity.

Freshwater extracts of starfish ovaries were used to purify the sperm-attracting peptide 'startrak' from Pycnopodia helianthoides using hydrophobic interaction chromatography and DEAE-high-pressure liquid chromatography. Partially purified attractant had a molecular mass of 13 kDa, estimated from gel filtration and polyacrylamide gel electrophoresis results. The purified attractant was subjected to amino acid analysis and direct sequencing, and was found to consist largely of a single peptide composed of an estimated 127 residues based on a molecular mass of 13kDa. An N-terminal sequence of amino acids from positions 3 to 34 was obtained and synthesized as: NH2-Ala-Glu-Leu-Gly-Leu-Cys-Ile-Ala-Arg-Val-Arg-Gln-Gln-Asn-Gln-Gly-Gln- Asp-Asp-Val-Ser-Ile-Tyr-Gln-Ala-Ile-Met-Ser-Gln-Cys-Gln-Ser-COOH. The synthetic peptide possessed sperm-attracting activity 130 times greater than the activity of partially purified startrak and showed a pattern of species-specificity of sperm chemotaxis similar to that of startrak. Antibody prepared against synthetic peptide removed the sperm-attracting activity from crude and partially purified preparations of startrak. The partial sequence of startrak was not homologous with that of any of the known echinoid sperm motility-activating peptides.

Amino Acid Sequence↗