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Biomedical subjects

N Müller

Publications and source records attributed to N Müller.

At least 19 recordsLinked to original sources
PubMed2003

PCR-based detection of canine Leishmania infections in formalin-fixed and paraffin-embedded skin biopsies: elaboration of a protocol for quality assessment of the diagnostic amplification reaction.

Diagnosis of the cutaneous form of canine leishmaniosis is mostly performed by histological or immunohistological examination of skin biopsies. In modern histology, the polymerase chain reaction (PCR) has gained increasing importance as a complementary tool to directly demonstrate the presence of parasite DNA in the tissue sections. For the present study, a previously described Leishmania-PCR has been further developed and optimised in view of its practicability for routine histological application. Since formalin-fixation of histological specimens causes partial DNA-destruction, which may hamper diagnostic PCR analysis, primers specific for the highly conserved alpha-actin gene sequences were used to pre-diagnostically assess the isolated sample-DNA for its functionality in a PCR-reaction. This alpha-actin-specific PCR detects DNA from a large variety of mammalian species and thus exhibits relevance for both human and veterinary medical application. A recombinant internal positive control was introduced to monitor possible sample-related inhibitory effects during the amplification reaction. We performed a retrospective evaluative study with 18 formalin-fixed samples from dogs with suspected or proven leishmaniosis. Six samples were PCR-incompatible. In turn, 9 of the other 12 samples were PCR-positive, and immunohistochemical results matched these findings. Based on these technical achievements, the Leishmania-PCR proved to be a valuable tool to complement conventional histological and immunohistological methods for diagnosis of cutaneous leishmaniosis in formalin-fixed, paraffin-embedded skin biopsies.

Actins↗
PubMed2003

Vaccination of mice against experimental Neospora caninum infection using NcSAG1- and NcSRS2-based recombinant antigens and DNA vaccines.

NcSAG1 and NcSRS2, the two major immunodominant tachyzoite surface antigens of the apicomplexan parasite Neospora caninum, were investigated for their potential as vaccine candidates in mice. Recombinant recNcSRS2 and recNcSAG1 were expressed in Escherichia coli as poly-histidine-tagged fusion proteins. Separate groups of mice were immunized with purified recNcSAG1, recNcSRS2, or a combination of both, and were then challenged with N. caninum tachyzoites. Subsequent experiments included intramuscular vaccination of mice with the eukaryotic expression plasmid pcDNA3 containing either NcSRS2 or NcSAG1 cDNA inserts, followed by a single booster with the corresponding recombinant antigens. Immunization with a crude somatic antigen (NC1-extract) was included in the experiments. Following challenge, the presence of the parasite in the different organs was assessed by a N. caninum-specific PCR, while the parasite burden in infected brain tissue was assessed by quantitative real-time PCR. Immunization of mice employing individual recombinant antigens, or combined recNcSAG1/recNcSRS2, resulted in a lower degree of protection against cerebral infection, when compared to combined DNA/recombinant antigen vaccination. Serological analysis showed that this protective effect was associated with the occurrence of antibodies directed against native parasite antigens in those animals receiving combined DNA/recombinant antigen vaccination. Conversely, mice immunized with recombinant antigens alone generated antibodies recognizing only the recombinant antigens. Mice experiencing clinical signs such as walking disorders, rounded back, apathy and paralysis were observed only in the untreated positive control groups, but never in the vaccinated groups. Our results suggest that a combined DNA/recombinant antigen-vaccine, based on NcSAG1 and NcSRS2, respectively, exhibited a highly significant protective effect against experimentally induced cerebral neosporosis in mice.

Animals↗
PubMed2003

Decreased sTNF-RI in migraine patients?

Tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) have recently been found to have a pain-mediating function in addition to their immunological, proinflammatory function. According to the hypothesis of neurovascular inflammation in migraine, these two cytokines could contribute to migraine pain generation. We analysed IL-6 and its soluble receptors sIL-6R and sgp130 as well as TNF-alpha and its soluble receptor sTNF-RI in 27 migraine patients and eight headache-free controls. Migraine patients tended to have less sTNF-RI (794 +/- 158 pg/ml) than controls (945 +/- 137 pg/ml). No differences in cytokine concentrations were observed. If TNF-alpha plays a role in migraine physiopathology, migraine patients may lack sufficient antagonistic sTNF-RI to neutralize hyperalgesic TNF-alpha during a migraine attack.

Adult↗
PubMed2003

Soluble interleukin-2 receptors increase during the active periods in cluster headache.

OBJECTIVE: To investigate whether cytokines are altered during the active period of cluster headache. BACKGROUND: Patients with cluster headache show activation of the hypothalamus in PET studies and via endocrinologic parameters. Data also suggest an inflammatory process occurs in cluster headache. A connection between the presumed inflammatory cause, an immunological activation, and the hypothalamus could be generated by certain cytokines. DESIGN AND METHODS: ELISA was used to determine the serum levels of soluble interleukin-2 receptors, interleukin-1, interleukin-6, and 2 soluble interleukin-6 receptors (sIL-6R and soluble gp130) in 18 patients with cluster headache (6 women and 12 men) during the cluster period and in 17 healthy controls who were headache-free (3 women and 14 men). RESULTS: Patients with cluster headache had significantly increased soluble interleukin-2 receptors (413.6+/-223 U/mL vs. 290.0+/-112 U/mL; P <.05) compared with controls. Serum levels of interleukin-1 (0.29+/-0.30 pg/mL vs. 0.13+/-0.13 pg/mL, n.s.), interleukin-6 (0.87+/-0.6 pg/mL vs. 0.91+/-0.7 pg/ml; n.s.), soluble interleukin-6 receptors (33,131+/-8,349 pg/mL vs. 35,063+/-7,606 pg/mL; n.s.), or soluble gp130 (289+/-59 pg/mL vs. 283+/-20 pg/mL; n.s.) did not differ between the 2 groups, although patients with cluster tended to have higher interleukin-1 values. CONCLUSIONS: Because elevated soluble interleukin-2 receptors indicate T cell activation, our findings suggest immune activation during cluster headache. Because interleukin-2 can activate the hypothalamus and stimulate the release of Corticotropin-releasing Factor (CRF), interleukin-2 could link a putative immunological cause of cluster headache with the observed hypothalamic activation. Systemic changes of interleukin-1 or the interleukin-6 system do not seem to play a role in cluster headache, as no alterations of serum levels were observed. Even so, unchanged serum levels do not exclude limited local production.

Adult↗
PubMed2003

[The transfusion law in Germany--an assessment].

Since July, 1998 the transfusion act regulates obligatory the transfusion management in Germany. The act aims to achieve greater safety for blood products and transfusion practices. Consequently the transfusion act, too, requires that a quality assurance system regarding the use of blood products is set up in hospitals.

Blood Transfusion↗
PubMed2002

Experimental verification of quadrupole-dipole interference in spin-resolved photoionization.

We have measured the spin polarization of Xe (4p)(-1) photoelectrons after ionization with circularly polarized light at photon energies close to the ionization threshold where a resonant enhancement of quadrupole transitions has recently been predicted. At a reaction angle of 90 degrees a nonvanishing longitudinal spin polarization component of about 4% clearly indicates a quadrupole contribution to the photoexcitation. This is the first experimental evidence for the influence of nondipole transitions on the photoionization process at excitation energies much below 1 keV in an observable other than the intensity angular distribution.

Journal Article↗
PubMed2002

Concurrent collection of in-line filtered platelets and red blood cells by apheresis.

Multicomponent apheresis procedures offer the possibility to collect standardized blood components as compared to whole blood donations. A new program for the concurrent collection of platelets (PLTs) and red blood cells (RBCs) was evaluated in a prospective study. Apheresis donors ( n=18) underwent concurrent collection of PLTs and RBCs using the Haemonetics MCS+ blood cell separator. Aliquots of PLTs and RBCs were collected during five to six passes of the discontinuous flow procedure. The platelet product was in-line filtered during the last pass of the separation procedure. After collection, saline-adenine-glucose-mannitol (SAGM) preservative solution was automatically added to the RBCs. Thereafter, the RBCs were in-line leukodepleted by gravity filtration at room temperature. The PLTs and RBCs were subsequently stored at 22+/-2 degrees C for 5 days and 4+/-2 degrees C for 35 days, respectively. The following in vitro parameters were evaluated over the storage periods: blood cell counts, glucose, lactate, lactate dehydrogenase, pH, plasma hemoglobin, and potassium. Two ready-to-use blood components from one donor were collected in an average procedure time of 86+/-10 min; 2.47+/-0.74 x 10(11) PLTs were collected in a product volume of 232+/-43 ml. The RBC volume averaged 280+/-20 ml and the hemoglobin content was 56.8+/-2.4 g per unit. The leukocyte contamination of the platelet product was 0.44+/-0.56 x 10(5) and the residual leukocyte content of the RBC product was 0.28+/-0.02 x 10(5). Storage data showed no relevant drop in pH. Day 35 results of the RBC products showed that all of the units had less than 0.8% hemolysis. Standardized PLT and RBC products of good quality can be concurrently collected with the MCS+ blood cell separator. In vitro testing of the products collected and stored for 5 and 35 days, respectively, met the Council of Europe criteria for leukodepleted blood products.

Blood Component Removal↗
PubMed2002

Caveolae and caveolin isoforms in rat peritoneal macrophages.

Caveolea are special (highly hydrophobic) plasma membrane invaginations with a diameter of 50-100 nm. Their characteristic features are the flask- or omega-shape and the lack of basket-like coat composed of clathrin. Caveolin-an integral membrane protein-is the principal component of caveolae membranes in vivo. Multiple forms of caveolin have been identified: caveolin-1alpha, caveolin-1beta, caveolin-2 and caveolin-3. They differ in their specific properties and tissue distribution. In this paper we summarize the morphological and biochemical data providing strong evidence about the existence and function of caveolae in rat peritoneal macrophages. When studied electron microscopically, the surface of both resident and elicited macrophages exhibited omega- or flask-shaped plasma membrane invaginations. There was a significant difference, however, in the number of these profiles: whereas in resident cells only a small amount of them was found on the cell surface, in elicited cells they were abundantly present on the plasma membrane. Using an antibody against the VIP21/caveolin-1 isoform we showed that these plasma membrane pits were indeed caveolae. The number and the appearance of caveolae were found to be in close correlation with the functional activity of these phagocytotic cells, indicating that the formation of caveolae is a highly regulated process. Using Western blot analysis two different proteins ( approximately 29 and approximately 20 kDa)-both labelled with anti-caveolin antibodies-were identified in resident and elicited macrophages that have been isolated from rat peritoneal cavity. The approximately 20 kDa protein was labelled specifically only by anti-VIP21/caveolin-1, while the approximately 29 kDa protein was labelled by both anti-VIP21/caveolin-1 and anti-caveolin-2 antibodies. The presence of the approximately 29 kDa protein was highly characteristic of resident cells, and only a small amount of approximately 20 kDa protein was detected in these cells. Elicitation has resulted in a significant increase in the amount of approximately 20 kDa protein labeled only with anit-VIP21/caveolin-1. Our morphological (confocal and electron microscopical) studies have shown that in resident cells caveolin was present in the cytoplasm, in smaller vesicles and multivesicular bodies around the Golgi area. Only a very small amount of caveolae was found on the cell surface of these cells. In elicited macrophages, caveolae (labelled with anti-VIP21/caveolin-1 antibody) appeared in large numbers on the cell surface, but caveolin detected by anti-caveolin-2 was also found in small vesicles and multivesicular bodies. These data support the idea that the expression of the approximately 29 kDa (caveolin-related) protein is insufficient for caveolae formation in resident cells, it can function as a modified, macrophage-specific caveolin-2 isoform. Our results strongly suggest that caveolin-1 plays a crucial role in the formation of caveolae: it is the amount of caveolin-1 that regulates the appearance of caveolae on the plasma membrane. Studying the endocytotic processes of resident and elicited macrophages we have found that elicited macrophages bound and internalized significantly larger amounts of fluid phase marker (HRP) and immune complex (peroxidase-antiperoxidase-PAP) than resident cells. Serial section analysis, double labelled immunocytochemistry, and filipin treatment were used to demonstrate that caveolae can pinch off from the plasma membrane and can take part in endocytotic processes as alternative carriers in elicited macrophages.

Animals↗
PubMed2002

Correlation between injuries sustained in the A17 coach accident and the seating location.

Road traffic accidents where coaches are involved are increasing. Having been confronted with a similar incident giving rise to the deployment of the medical disaster plan of West Flanders, we have been looking for particular mechanisms to explain the passengers' injuries. We identified some technical aspects (e.g. foot bars) to consider when safety precautions have to be taken.

Accidents, Traffic↗
PubMed2001

Utility of a lung biopsy for the diagnosis of idiopathic pulmonary fibrosis.

It is not known if a surgical lung biopsy is necessary in all patients for the diagnosis of idiopathic pulmonary fibrosis (IPF). We conducted a blinded, prospective study at eight referring centers. Initially, cases were evaluated by clinical history and examination, transbronchial biopsy, and high-resolution lung computed tomography scans. Pulmonologists at the referring centers then assessed their certainty of the diagnosis of IPF and provided an overall diagnosis, before surgical lung biopsy. The lung biopsies were reviewed by a pathology core and 54 of 91 patients received a pathologic diagnosis of IPF. The positive predictive value of a confident (certain) clinical diagnosis of IPF by the referring centers was 80%. The positive predictive value of a confident clinical diagnosis was higher, when the cases were reviewed by a core of pulmonologists (87%) or radiologists (96%). Lung biopsy was most important for diagnosis in those patients with an uncertain diagnosis and those thought unlikely to have IPF. These studies suggest that clinical and radiologic data that result in a confident diagnosis of IPF by an experienced pulmonologist or radiologist are sufficient to obviate the need for a lung biopsy. Lung biopsy is most helpful when clinical and radiologic data result in an uncertain diagnosis or when patients are thought not to have IPF.

Biopsy↗
PubMed2001

Hydrophobic forms of morphine-6-glucosides.

NMR spectroscopy of 6-acetylmorphine (6-AM), a chloroform-soluble model compound for the hydrophilic, highly potent analgesic drug morphine-6-glucoronide (M6G), in a hydrophobic solvent indicates one hydrogen bonded water molecule per molecule of 6-AM. By analysis of nuclear Overhauser enhancements (NOEs) we find a 6-AM dimer in which the monomers are linked by two water molecules. Molecular modeling studies underscore the stability of such dimeric structures involving water molecules for 6-AM and point out their more lipophilic character allowing penetration of the blood-brain barrier.

Dimerization↗
PubMed2001

The G protein beta3 subunit 825T allele is a genetic marker for enhanced T cell response.

The G protein beta3 subunit (GNB3) 825T allele is predictive of enhanced Gi protein activation. Studying the influence of C825T allele status on cellular in vitro immune responses towards recall antigens and interleukin-2 stimulation we observed a 2-4-fold, significantly increased proliferation in homozygous 825T (TT) vs. C825 allele (CC) carriers. Furthermore, lymphocyte chemotaxis and CD4(+) T cell counts of individuals with TT+TC genotypes were significantly enhanced compared to the CC genotype. In summary, it appears that C825T allele status is highly predictive of immunocompetence and could be a candidate gene in disorders associated with inadequate immune response.

Alleles↗
PubMed2001

Increased titers of antibodies against streptococcal M12 and M19 proteins in patients with Tourette's syndrome.

It has been suggested that a post-streptococcal autoimmune process may be involved in the pathogenesis of a subgroup of children with tics and obsessive-compulsive symptoms (PANDAS). Elevated antibody titers against streptococcal antigens have also been described in adult patients suffering from Tourette's syndrome (TS). In order to characterise further streptococcal antigens, we focussed on M proteins. M proteins are a major virulence factor of group A streptococci and known to evoke an immunologic cross-reaction with diverse epitopes of human tissue including brain tissue. Therefore, antibodies against M proteins may play a role in the pathophysiology of at least a subgroup of TS patients. Antibodies against M proteins were studied in 25 adult patients suffering from TS and 25 healthy controls after careful medical examination. The antibody titers against the peptides M1, M4, M6, M12 and M19 were estimated by ELISA. Our results show increased titers of antibodies against the streptococcal M12 and M19 proteins in TS patients as compared with controls, while antibody titers against M1, M4 and M6 did not differ between the TS and control groups. Elevated serum titers of antibodies against M12 and M19 proteins support the view that a streptococcus-induced autoimmune process may be involved in TS. The finding of a possible autoimmune origin of TS has implications for both pathophysiology and future therapeutic strategies.

Adolescent↗
PubMed2001

Asymmetry in photoelectron emission from chiral molecules induced by circularly polarized light.

In photoionization of free, unoriented chiral molecules with circularly polarized radiation, a significant circular dichroism, i.e., an asymmetry in the forward-backward electron emission, has been observed in the photoelectron angular distribution. This leads also to an asymmetry in the momentum transfer to the photoions. The spectra for the left- and right-handed enantiomers of bromocamphor exhibit asymmetries up to several percent which vary as a function of orbital binding energy. This enantioselective effect can similarly occur for biomolecules with handedness, like amino acids, and may thus be a contributing factor related to the origin of the terrestrial biomolecular homochirality.

Journal Article↗
PubMed2001

Social anxiety disorder and the risk of depression: a prospective community study of adolescents and young adults.

BACKGROUND: Social anxiety disorder (SAD) (also known as "social phobia") is frequently comorbid with major depression, and in such cases, almost always precedes it. This has led to interest in SAD as a possible modifier of the risk and/or course of mood disorders. METHODS: Data come from a prospective, longitudinal epidemiologic study of adolescents and young adults (aged 14-24 years) in Munich, Germany. Respondent diagnoses (N = 2548) at baseline and follow-up (34-50 months later) are considered. The influence of SAD at baseline on the risk, course, and characteristics of depressive disorders (ie, major depression or dysthymia) at follow-up is examined. RESULTS: The baseline prevalence of SAD was 7.2% (95% confidence interval [CI], 6.1%-8.4%). Social anxiety disorder in nondepressed persons at baseline was associated with an increased likelihood (odds ratio [OR] = 3.5; 95% CI, 2.0-6.0) of depressive disorder onset during the follow-up period. Furthermore, comorbid SAD and depressive disorder at baseline was associated with a worse prognosis (compared with depressive disorder without comorbid SAD at baseline). This is exemplified by the greater likelihood of depressive disorder persistence or recurrence (OR = 2.3; 95% CI, 1.2-4.6) and attempted suicide (OR = 6.1; 95% CI, 1.2-32.2). CONCLUSIONS: Social anxiety disorder during adolescence or young adulthood is an important predictor of subsequent depressive disorders. Moreover, the presence of comorbid SAD in adolescents who are already depressed is associated with a more malignant course and character of subsequent depressive illness. These findings may inform targeted intervention efforts.

Adolescent↗
PubMed2001

Probing protein stabilization by glycerol using electrospray mass spectrometry.

This study shows that electrospray ionization mass spectrometry (ESI-MS), combined with a heated turbo ion-spray interface, allows monitoring protein stabilization by glycerol in solution. Measurements obtained with the two proteins lysozyme and cytochrome c are presented. The observed mass-to-charge (m/z) distributions reveal the stabilizing effect of the additive on the protein conformations against temperature and acid-induced unfolding, as well as against denaturation by acetonitrile. The data obtained with lysozyme allow detection of minor conformational changes upon glycerol addition to the native protein, and suggest that the protein structure in the presence of the additive is slightly compressed compared with its state in water. This result corroborates previous evidence obtained by nuclear magnetic resonance. It is also shown that analysis of the m/z distributions obtained by ESI-MS can lead to detection of partially folded and partially populated states in protein samples.

Animals↗