Biomedical subjects

S Boehmer

Publications and source records attributed to S Boehmer.

8 recordsLinked to original sources

PubMed2006

Occurrence of perfluorinated substances in an adult German population in southern Bavaria.

OBJECTIVES: Perfluorinated compounds (PFCs) are a large group of chemicals produced for several decades and widely used for many industrial and consumer applications. Because of their global occurrence in different environmental media, their persistence, and their potential to bioaccumulate in organisms they are of toxicological and public concern. METHODS: In the present study, the internal exposure to perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in 356 human plasma samples collected from an adult population in Germany in 2005 is quantified. RESULTS: We were able to detect the target analytes in all plasma samples and observed a significant correlation between the PFOS and PFOA concentrations. In female participants, the levels of PFOS and PFOA ranged between 2.5-30.7 (median: 10.9 microg/l) and 1.5-16.2 microg/l (median: 4.8 microg/l), respectively. In males we observed concentrations from 2.1 to 55.0 microg/l (median: 13.7 microg/l) for PFOS and from 0.5 to 19.1 microg/l (median: 5.7 microg/l) for PFOA. A significant correlation between both PFOS and PFOA concentrations and gender was observed. We also found increased levels of the PFCs with increasing age of the participants, but this association reached statistical significance among females only. CONCLUSIONS: Our data agree well with results of other recent studies in Europe and suggest that the current exposure of the adult German population is lower than the exposure of the US and Canadian population. The sources of human exposure are currently not well understood. Toxicological implications are restricted to animal studies and occupational investigations not adequate for quantitative risk assessment in humans. Overall, more scientific research is necessary to characterize the body burden of PFCs (especially for relevant subsets of the population) and the main sources and routes, which are responsible for human exposure and possible health implications of these compounds.

Adolescent↗

PubMed1997

Prenatal ultrasonographic and molecular diagnosis of Apert syndrome.

Apert syndrome is a rare craniosynostosis syndrome with significant bilateral syndactyly of the hands and feet. Usually it is detected by ultrasonography during the third trimester unless there is a family history. We present an interesting sporadic case with features consistent with Apert syndrome detected as early as the first trimester. A first-trimester ultrasound evaluation prior to chorionic villus sampling (CVS) for maternal age 41 was within normal limits except for the suggestion of a 'mitten-like' hand and proximally placed thumb. Mid-trimester ultrasound was not diagnostic; however, following the development of polyhydramnios in the third trimester, the evaluation of the digits and facial features were strongly suggestive of Apert syndrome. Amniocentesis was performed and a molecular diagnosis of Apert syndrome was made and confirmed on cord blood.

Acrocephalosyndactylia↗

PubMed1988

Gastrointestinal blood loss in haemodialysis patients during use of a low-molecular-weight heparinoid anticoagulant.

In a randomised cross-over study we assessed total blood loss in 14 dialysis patients using 59Fe as a marker for measurement in a whole-body counting system. In one period the patients received standard heparin, in the other ORG 10172, a new low-molecular-weight-heparinoid. Our results show no significant difference between the two study periods with regard to blood loss and dialyser blood retention. In some patients a delayed bleeding ('oozing') from the puncture site was noticed as a side-effect of treatment with the low-molecular-weight-heparinoid. We conclude that this heparinoid is effective as an anticoagulant in regular dialysis treatment, but it seems to have no advantage over standard heparinisation with regard to occult bleeding. This may be related to the prolonged plasma anti-Xa activity (30.8 h) of this compound compared to standard heparin in dialysis patients.

Adult↗

PubMed1984

Dissociative effects of a novel immunomodulating agent (CP-20, 961) on host defenses of mice.

The antimicrobial and antitumor effects of CP-20,961, a synthetic lipoid amine with immunomodulating properties, were investigated. Mice given CP-20,961 ip seven or three days before challenge with ip Listeria monocytogenes had a lower mortality than control mice. By contrast, CP-20,961 did not protect against lethal challenges of either Salmonella typhimurium or Toxoplasma gondii. In parallel with the in vivo studies, peritoneal macrophages from CP-20,961-injected mice inhibited multiplication of L. monocytogenes but not T. gondii. Further studies demonstrated that CP-20,961 protected mice against an ip challenge of P815 tumor cells as measured by survival time. This correlated with the ability of stimulated peritoneal macrophages to inhibit (3H-TdR uptake inhibition) and kill (Cr51 release) P815 cells in vitro. These data indicate that CP-20,961 affords protection against an ascitic mastocytoma tumor line and at least one, but not all, intracellular pathogens. The dissociation of the immunomodulating effect, which was reflected in peritoneal macrophage function, may be characteristic of this new class of immunomodulators.

Adjuvants, Immunologic↗

PubMed1981

Sedimentation velocity of DNA in isokinetic sucrose gradients: calibration against molecular weight using fragments of defined length.

The relationship between sedimentation coefficient and molecular weight for DNA sedimenting in preformed alkaline and neutral sucrose gradients was determined using absolute molecular weight standards (restriction fragments of plasmid pBR322 and phage lambda DNA). The range of calibration for alkaline gradients was extended to small DNA fragments (652 base-pairs) for the first time. The exponent b in the equation S20 degrees, w = aMb was found to be 0.380 in neutral gradients and 0.410 in alkali. The latter value differs significantly from previous estimates. The gradients were isokinetic, and the distance sedimented was shown to be directly proportional to the sedimentation coefficient at all times.

Bacteriophage lambda↗

PubMed1981

Recombination of uracil-containing lambda bacteriophages.

Controlled incorporation of uracil into the deoxyribonucleic acid (DNA) of lambda bacteriophages was achieved by growth on dut ung thy mutants of Escherichia coli. The frequency of substitution of uracil for thymine, estimated by alkaline sucrose sedimentation of phage DNA treated in vitro with uracil DNA glycosylase, ranged from 0.17 to 1.9%. The corresponding ratio between the plating efficiencies on wild-type (Ung+) and glycosylase-deficient (Ung-) bacteria ranged from 0.70 to 0.05. If a single-hit dependence of plating efficiency on uracil content is assumed, the probability that any given uracil residue is lethal is approximately 1% (about one-fifth the probability for a pyrimidine dimer). The effect of uracil on recombination was studied in experiments with lambda tandem duplication phages (ethylenediaminetetraacetic acid [EDTA] sensitive), which are converted to single-copy phages (EDTA resistant) by general recombination. For repressed infections (of homoimmune lysogens), recombination was measured by a two-stage assay (DNA extraction, transfection of spheroplasts, and EDTA treatment). The frequencies observed for uracil-containing phages (2 to 4%) were 5 to 10 times higher than control values. However, comparisons with ultraviolet irradiated phages indicated that uracil residues promoted recombination less than 1/100 as efficiently as ultraviolet-induced lesions. Recombination of uracil-containing phages during repressed infections was negligible in recA and partially reduced in recB bacteria. Recombination was very low in ung cells, suggesting that excision repair was responsible for the stimulation. Interestingly, uracil-stimulated recombination was elevated about twofold in xth bacteria.

Bacteriophage lambda↗

PubMed1978

Antagonists of DNA gyrase inhibit repair and recombination of UV-irradiated phage lambda.

Intracellular lambda DNA (from EDTA-sensitive tandem duplication phages) was extracted from infected rec+ bacteria and scored for infectivity and recombination (loss of duplication) by transfection of recA recB spheroplasts and subsequent assay for EDTA resistance. When phage development was blocked by repressor or by antibiotics (chloramphenicol and/or rifampin), the apparent recombination frequency was about 0.1% above the background value for recA infections. Prior irradiation of the phage greatly stimulated recombination; the frequency was 20% when UV fluence was 140 J/m2. Repair (recovery of infectivity) and recombination of irradiated phage DNA proceeded readily in the presence of chloramphenicol and rifampin. Inhibitors of DNA gyrase (coumermycin and oxolinic acid) blocked repair and reduced recombination. UV-stimulated recombination was very low in recA but nearly normal in recB cells: repair was reduced in both mutant strains. The recombination remained high as phage/cell ratios less than unity.

Aminocoumarins↗

PubMedDate not supplied

In vitro cytobiological effects of human herpesviruses 6 and 7: immunohistological monitoring of apoptosis, differentiation and cell proliferation.

Two human herpesviruses, HHV-6 and HHV-7, recently identified and closely related, were studied for their influence on cellular apoptosis and proliferation. Infection was monitored by viral DNA--and antigen expression. Apoptosis and cell proliferation were determined by immunocytological techniques and the markers p53, p21WAF/Cip, Bax, Bak, Bcl-2, cyclin D1 and PCNA, and also screened for signal transduction indicators such as c-H-ras, c-fos and raf-1. Cell differentiation and function was monitored by determining cell membrane receptors including Fas and CD specificities, and by ELISA tests for interleukin production. Both HHV-6 and HHV-7 readily infected their target cells, yet virus antigen expression and virus replication were less active in HHV-7 infection. Both viruses also induced GM-CFS production. Cell differentiation in terms of CD receptor expression was more pronounced in HHV-6 than in HHV-7 infection. No differences were found in the activity of signal transduction factors. There were quantitative differences in the activation of p53, Bax, p21WAF and Bcl-2 in HHV 6-infected CBC as compared to HHV-7 infection supporting the apoptosis cycle. CyclinD1 activity remained at lower levels in HHV-7 infected CBC, yet was high in similarly infected transformed SupT1 cells. In contrast, HHV-6 supported rather the p53/p21WAF apoptosis pathway in both untransformed CBC and transformed HSB1 cells. Both herpesviruses, HHV-6 and HHV-7, thus possessed similar biological activities in cultures of non-transformed susceptible cells, although with certain quantitative differences. The data reported here may further support the notion that HHV-7 is less active in inducing apoptosis thus favoring continued cell proliferation. The mechanism by which these viruses interfere with the network control of cell proliferation, differentiation and apoptosis appear more complicated than shown here and therefore afford a more detailed study, including a more sensitive technology than immunohistology.

Antigens, Viral↗