Effects of subchronic inhalation exposure of rats to emissions from a diesel engine burning soybean oil-derived biodiesel fuel.

There is increasing interest in diesel fuels derived from plant oils or animal fats ("biodiesel"), but little information on the toxicity of biodiesel emissions other than bacterial mutagenicity. F344 rats were exposed by inhalation 6 h/day, 5 days/wk for 13 wk to 1 of 3 dilutions of emissions from a diesel engine burning 100% soybean oil-derived fuel, or to clean air as controls. Whole emissions were diluted to nominal NO(x) concentrations of 5, 25, or 50 ppm, corresponding to approximately 0.04, 0.2, and 0.5 mg particles/m(3), respectively. Biologically significant, exposure-related effects were limited to the lung, were greater in females than in males, and were observed primarily at the highest exposure level. There was a dose-related increase in the numbers of alveolar macrophages and the numbers of particles in the macrophages, as expected from repeated exposure, but no neutrophil response even at the highest exposure level. The macrophage response was reduced 28 days after cessation of the exposure. Among the high-level females, the group mean lung weight/body weight ratio was increased, and minimal, multifocal bronchiolar metaplasia of alveolar ducts was observed in 4 of 30 rats. Lung weights were not significantly increased, and metaplasia of the alveolar ducts was not observed in males. An increase in particle-laden macrophages was the only exposure-related finding in lungs at the intermediate and low levels, with fewer macrophages and fewer particles per macrophage at the low level. Alveolar histiocytosis was observed in a few rats in both exposed and control groups. There were statistically significant, but minor and not consistently exposure-related, differences in body weight, nonpulmonary organ weights, serum chemistry, and glial fibrillary acidic protein in the brain. There were no significant exposure-related effects on survival, clinical signs, feed consumption, ocular toxicity, hematology, neurohistology, micronuclei in bone marrow, sister chromatid exchanges in peripheral blood lymphocytes, fertility, reproductive toxicity, or teratology. This study demonstrated modest adverse effects at the highest exposure level, and none other than the expected physiological macrophage response to repeated particle exposure at the intermediate level.

MTBE inhaled alone and in combination with gasoline vapor: uptake, distribution, metabolism, and excretion in rats.

The purpose of these studies was to extend previous evaluation of methyl tert-butyl ether (MTBE)* tissue distribution, metabolism, and excretion in rats to include concentrations more relevant to human exposure (4 and 40 ppm) and to determine the effects of coinhalation of the volatile fraction of unleaded gasoline on the tissue distribution, metabolism, and excretion of MTBE. Groups of male F344 rats were exposed nose-only for 4 hours to 4, 40, or 400 ppm 14C-MTBE or to 20 or 200 ppm of the light fraction of unleaded gasoline (LFG) containing 4 or 40 ppm 14C-MTBE, respectively. To evaluate the effects of repeated inhalation of LFG on MTBE tissue distribution, metabolism, and excretion, rats were exposed for 4 hours on each of 7 consecutive days to 20 or 200 ppm LFG with MTBE (4 or 40 ppm) followed on the eighth day by a similar exposure to LFG containing 14C-MTBE. Subgroups of rats were evaluated for respiratory parameters, initial body burdens, rates and routes of excretion, and tissue distribution and elimination. The concentrations of MTBE and its chief metabolite, tert-butyl alcohol (TBA), were measured in blood and kidney immediately after exposure, and the major urinary metabolites-2-hydroxyisobutyric acid (IBA) and 2-methyl-1,2-propanediol (2MePD)-were measured in urine. Inhalation of MTBE alone or as a component of LFG had no concentration-dependent effect on respiratory minute volume. The initial body burdens of MTBE equivalents achieved after 4 hours of exposure to MTBE did not increase linearly with exposure concentration. MTBE equivalents rapidly distributed to all tissues examined, with the largest percentages distributed to liver. The observed initial body burden did not increase linearly between 4 and 400 ppm. At 400 ppm, elimination half-times of MTBE equivalents from liver increased and from lung, kidney, and testes decreased compared with the two smaller doses. Furthermore, at 400 ppm the elimination half-time for volatile organic compounds (VOCs) in breath was significantly shorter and the percentage of the initial body burden of MTBE equivalents eliminated as VOCs in breath increased significantly. These changes probably reflect a saturation of blood with MTBE at 400 ppm and strongly suggest that the uptake and fate of MTBE are notably different at exposure concentrations above and below 400 ppm. Single and repeated coexposure to 20 and 200 ppm LFG with MTBE had opposite effects on the total body burden of MTBE equivalents present at the end of exposures compared with those achieved after 4 and 40 ppm MTBE exposures: 20 ppm LFG increased and 200 ppm LFG significantly decreased the burdens of MTBE equivalents present. The effects of coexposure to LFG on blood levels of MTBE equivalents paralleled the effects on body burden. These differences in overall uptake of MTBE equivalents cannot be attributed to alterations of minute volume. The reason for the increase in overall uptake after 20-ppm LFG exposure is not clear. Decreased MTBE absorption (uptake) after single and repeated coexposure to 200 ppm LFG may be due to a decrease in solubility of MTBE in blood caused by inhalation of other hydrocarbons. Investigations on the blood/air partition coefficient of MTBE in the absence and presence of LFG would be needed to confirm this hypothesis. Single and repeated coexposure to either 20 or 200 ppm LFG significantly decreased the percentage of the initial body burden from MTBE equivalents in tissues, including liver, kidney, and testes, immediately and 72 hours after

Electrospray ionization detection of inherently nonresponsive epoxides by peptide binding.

A small organic molecule that is inherently nonresponsive to electrospray analysis, 1,3-butadiene diepoxide, was analyzed via electrospray ionization (ESI) by binding it to various peptides and observing the product at the characteristic mass shift. The epoxide reacted only with peptides with arginines in their sequence, most likely through a base-catalyzed ring opening to form a covalently bound product. A calibration curve linear over 3 orders of magnitude was generated for the butadiene diepoxide/peptide adduct. Several other epoxides were also reacted with the peptide of choice (angiotensin II), and adducts of these epoxides with the peptide were observed as well, demonstrating the versatility of this method for the analysis of small epoxides. This study demonstrates the possibility of assaying epoxides bound to peptides or proteins in biological samples. Furthermore, it demonstrates an important concept that could be applied to other analytical problems in electrospray: the ability to react an analyte that is nonresponsive to electrospray analysis with an analyte well suited for the technique, and accomplish quantitation based on the adduct formed between the two.

Rapid DNA typing of HLA-B27 allele by real-time PCR using lightcycler technology.

For clinical diagnostic routine we developed a fast DNA typing of HLA-B27 by PCR and real-time detection using LightCycler technology. The method combines the sensitivity and specificity of PCR with the swiftness of the LightCycler system. The amplification step was performed with a primer set coding for a region in the third exon common to B*2701 to B*2705. The PCR cycles were monitored continuously using the SYBR Green I dye. Beta-globin was used as an internal control. An analysis of 32 samples with one PCR run was completed within 40 minutes. After amplification a melting curve analysis permitted the accurate identification of the PCR amplicons. The mean melting temperatures (Tm) were 90.5 degrees C and 87.3 degrees C, which are characteristic for HLA-B27 and beta-globin, respectively. A comparison of 300 samples which were typed for HLA-B27 with a conventional sequence-specific polymerase chain reaction (SSP-PCR) and with the new method demonstrated a perfect correlation (specificity 100%). In summary, the method described is fast, reliable, cost-effective and well adapted for routine laboratory testing.

Predicting electrospray response from chromatographic retention time.

The relationship between electrospray ionization response and HPLC retention time was explored. For the series of small peptides studied, higher ESI response was observed for analytes with longer reversed-phase HPLC retention times. This correlation existed for both experimentally measured retention times and those calculated from amino acid retention coefficients. This study is useful t

Advances in surface plasmon resonance biomolecular interaction analysis mass spectrometry (BIA/MS).

Ongoing, worldwide efforts in genomic and protein sequencing, and the ability to readily access corresponding sequence databases, have emphatically driven the development of high-performance bioanalytical instrumentation capable of characterizing proteins and protein-ligand interactions with great accuracy, speed and sensitivity. Two such analytical techniques have arisen over the past decade to play key roles in the characterization of proteins: surface plasmon resonance biomolecular interaction analysis (SPR-BIA) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF). SPR-BIA is used in the real-time investigation of biomolecular recognition events, and is thereby capable of providing details on the association and dissociation kinetics involved in the interaction, information ultimately leading to the determination of dissociation constants involved in the event. MALDI-TOF is used in the structural characterization, identification and sensitive detection of biomolecules. Although the two techniques have found many independent uses in bioanalytical chemistry, the combination of the two, to form biomolecular interaction analysis mass spectrometry (BIA/MS), enables a technique of analytical capabilities greater than those of the component parts. Reviewed here are issues of concern critical to maintaining high-levels of performance throughout the multiplexed analysis, as well as examples illustrating the potential analytical capabilities of BIA/MS.

Mass spectrometric methods for evaluating point mutations.

Two methods for internally calibrating spectra resulting from the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry analysis of partially digested proteins are described. Partial digestion of proteins results in a large number of ion signals present in the MALDI-TOF mass spectrum, which in turn represent a significant over-sampling of each amino acid present in the analyte. This over-sampling allows ion signals of undisputed origin to be used as internal calibrants for the evaluation of fragments suspected to contain point mutations. Correlated with the correct amino acid sequence, the mass values of all ion signals (calibrants and analytes) are observed to fall into a single low-error data set. Conversely, empirically derived data applied to an incorrect sequence split the data into subsets of different errors. The methods take advantage of the self-consistent nature of data generated during the enzymatic mass mapping of proteins using MALDI-TOF, and they aid in the rapid, sensitive and accurate evaluation of point mutations present in proteins.

Surface plasmon resonance biomolecular interaction analysis mass spectrometry. 1. Chip-based analysis.

The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) in concert with surface plasmon resonance-based biomolecular interaction analysis (SPR-BIA) is reported. A chip-based biosensor unit was used to simultaneously monitor biomolecular interactions taking place on four different regions of the sensor chip (flow cells). Species retained during SPR-BIA were then identified by performing MALDI-TOF directly from within the area of the flow cells. Analyses were performed on an antibody/antigen/antibody system with detection limits in the low-femtomole range. The combined assay demonstrates the use of SPR-BIA to evaluate the relative stability of sequential solution-phase interactions, as well as, upon MALDI-TOF analysis, the ability to unambiguously confirm the presence of species retained during the interaction analysis.

Surface plasmon resonance biomolecular interaction analysis mass spectrometry. 2. Fiber optic-based analysis.

Fiber optic probe-based surface plasmon resonance (SPR) detection has been used in combination with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry for the rapid, sensitive, and selective detection of biomolecules. SPR was used to monitor the covalent immobilization of a polyclonal antibody to the surface of a fiber optic probe. The derivatized probe was then used for the selective detection (from solution) of the corresponding antigen and a secondary antibody directed toward the antigen. Species retained during the SPR detection process were next analyzed by direct MALDI-TOF analysis of the probe surface (after exposed to the MALDI matrix and introduction into the mass spectrometer). The combined approach allowed for the two-dimensional detection of biomolecules, with SPR analysis yielding quantitative information pertinent to the binding events and MALDI-TOF providing details on the qualitative nature of the binding partners.

BIA/MS: interfacing biomolecular interaction analysis with mass spectrometry.

Biomolecular interaction analysis (BIA) which utilizes surface plasmon resonance (SPR) detection of affinity-captured analytes has been interfaced with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI). Femtomole quantities of a peptide, myotoxin a, were detected by direct MALDI analysis of sensor chips used during BIA of a polyclonal anti-myotoxin a IgG/myotoxin a system. Further, different interactive surfaces (flow cells) present on a single biosensor were targeted individually for mass spectrometric analysis. System compatibility of the combined approach was demonstrated with sensitivities, detection limits, and analytical performances comparable to those intrinsic to the individual analyses. The combined approach unites the real-time capabilities of SPR-based BIA with the qualitative specificity of mass spectrometry.

Mass spectrometric immunoassay.

A new, general method of immunoassay is demonstrated. The approach is based on the microscale immunoaffinity capture of target antigens followed by mass-specific identification and quantitation using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Immunoaffinity capture of antigens effectively overcomes signal suppression effects typically encountered during traditional matrix-assisted laser desorption/ionization analysis of complex biological mixtures while simultaneously concentrating the analyte into a small volume. Mass spectrometric detection of antigens is unambiguous, as antigen signals are observed at characteristic mass-to-charge values in the mass spectrum, offering a high level of immunity to artifacts due to nonbiospecific retention of mixture components. However, the most important aspect of such mass-specific detection is the ability to use a single assay to screen biological systems for the presence of multiple, mass-resolved antigens. Analyte quantitation is possible by using a single antibody to capture both the antigen and an antigen variant which has been chemically modified to have a different mass. With proper calibration, the relative signal intensities of the two species in the mass spectrum can be used to determine the antigen concentration. Sample incubation and processing methods were such that a typical analysis could be performed in less than 1 h while subnanomolar sensitivities were maintained. The technique has been used for the rapid, selective, and quantitative screening of human blood for the presence of myotoxin a, and Mojave toxin form the venoms of the prairie rattlesnakes, Crotalus viridis viridis, and and the Mojave rattlesnake, Crotalus scutulatus scutulatus.

Peptide characterization using bioreactive mass spectrometer probe tips.

A method has been developed for the rapid and sensitive mass spectrometric characterization of peptides. The approach uses bioreactive mass spectrometer probe tips, incorporating covalently bound enzymes, which are capable of modifying biomolecules for analytical purposes. In the demonstrated cases, enzymatic proteolysis is initiated upon application of analyte to the probe tips, time is allowed for digestion, and the products are analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The probe tips have been used for proteolytic mapping and partial sequence determination of picomole quantities of peptide. Analysis times were approximately 30 min. Two methods of database search were utilized. The first used limited peptide sequence information and parent molecular weight, while the second used exclusively the molecular weights of a number of endoproteolytic fragments. A simple method of comparing the match of experimental data for a tryptic digest with the results of a search is described.

[Cryptosporidiosis in immunocompetent patients. Epidemiology and clinical picture]. / Kryptosporidiose bei immunkompetenten Patienten. Epidemiologie und Klinik.

Cryptosporidiosis species were demonstrated in stool of 1.9% of 1600 unselected patients with enteritis (practically evenly divided between children and adults). Further investigations revealed seven cases of enteritis among family members. In eight patients there was a double infection with Cryptosporidium plus another enteritis pathogen. The most frequent clinical symptoms were diarrhea, vomiting, cramp-like abdominal pain, fever and headache. The mean period of parasite excretion was 14 days. Spontaneous cure occurred in all patients. Since cryptosporidiosis is relatively common not only in those with lowered resistance but also those who are immune-competent, search for Cryptosporidium should be included in all tests for etiologically uncertain cases of enteritis.

[An investigation into the influence of human serum on the in-vitro activity of various cephalosporins (author's transl)]. / Untersuchung über den Einfluss von Humanserum auf die In-vitro-Aktivität verschiedener Cephalosporine.

Cephalosporins are being given more and more frequently empirically as initial therapy, until the bacteriological findings become available. The wide selection of cephalosporins available make the choice of the most suitable one difficult for the clinician. Cephazolin, cephradine and cephacetrile were tested against three standard bacteria strains (Escherichia coli, Staphylococcus aureus, Kelebsiella pneumoniae) in normal broth and with the addition of 30% inactivated human serum; the geometric mean of the minimum inhibitory concentration (MIC) was determined by serial dilution, and the minimum bactericidal concentration (MBC) by inoculation onto solid medium. On the addition of 30% serum, cephazolin showed a reduction in effectivity of up to 360% for the MIC and up to 74% for the MBC, cephacetril up to 250% for the MIC and 100% for the MBC, and cephradin a maximum loss of 16%. Successful treatment of a severe infection requires a high drug level or a corresponding tissue titer. Due to the high tissue concentration of cephradin and the unrivalled stable antibacterial effectivity in serum, this antibiotic can be recommended for clinical use.