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Biomedical subjects

N Müller

Publications and source records attributed to N Müller.

At least 73 records · Page 4Linked to original sources
PubMed2001

Use of a novel DNA melting profile assay for the identification of PCR-amplified genomic sequences encoding for variant-specific surface proteins from the clonal GS/M-83-H7 line of Giardia lamblia.

During infections, Giardia lamblia undergoes a continuous change of its major surface antigens, the variant-specific surface proteins (VSPs). Many studies on antigenic variation have been performed using G. lamblia clone GS/M-83-H7, which expresses surface antigen VSP H7. The present study was focused on the identification and characterization of vsp gene sequences within the genome of the clonal G. lamblia GS/M-83-H7 line. For this purpose, we applied a PCR which specifically amplified truncated sequences from the 3'-terminal region of the vsp genes. Upon cloning, most of the vsp gene amplification products were shown to be approximately identical in size and thus could not be distinguished from each other by conventional gel electrophoresis. In order to pre-estimate the sequence complexity within the large panel of vsp clones isolated, we elaborated a novel concept which facilitated our large-scale genetic screening approach: PCR products from cloned DNA molecules were generated and then subjected to a DNA melting profile assay based on the use of the LightCycler Instrument. This high-throughput assay system proved to be well suited to monitor sequence differences between the amplification products from closely related vsp genes and thus could be used for the primary, sequence-related discrimination of the corresponding clones. After testing 50 candidates, vsp clones could be divided into five groups, each characterized by an individual DNA melting profile of the corresponding amplification products. Sequence analysis of some of these 50 candidates confirmed data from the aforementioned assay in that clones were demonstrated to be identical within, but different between, the distinct groups. The nucleotide and deduced amino acid sequences of five representative vsp clones showed high similarities both among each other and also with the corresponding gene segment of the variant-specific surface antigen (VSP H7) expressed by the original GS/M-83-H7 variant type. Furthermore, three of the genomic vsp sequences turned out to be identical to vsp sequences that represented previously characterized transcription products from in vivo- or in vitro-switched GS/M-83-H7 trophozoites. In conclusion, the DNA melting profile assay seems to be a versatile tool for the PCR-based genotyping of moderately or highly diversified sequence orthologues.

Amino Acid Sequence↗
PubMed2001

Molecular characterisation of a predominant antigenic region of Giardia lamblia variant surface protein H7.

During infection, the intestinal protozoan parasite Giardia lamblia undergoes continuous antigenic variation which is determined by diversification of the parasite's major surface antigen, named VSP (variant surface protein). One member from this protein family, VSP H7, is expressed by G. lamblia clone GS/M-83-H7. In the present study, we characterised a highly antigenic portion of VSP H7 which is positioned inside a 130 amino acid C-terminal region of the protein. This region overlaps with a cysteine-rich motif that is rather conserved within the VSP family. Detailed molecular dissection of the antigenic portion monitored a 12 amino acid peptidyl structure which constitutes a non-conformational epitope of VSP H7. In the murine host, this epitope is recognised relatively early (before day 10 p.i.) during infection and stimulates a strong intestinal immunoglobulin A response. At late infective stages (after day 10 p.i.) this immune reaction is progressively complemented by reactions against 'late' antigenic epitopes which are also located inside the 130 amino acid antigenic portion but in closer proximity to the C-terminal end of VSP H7 than the 12 amino acid epitope. Both the high antigenicity and the conserved character suggest that the 12 amino acid epitope is a key factor within the immunological interplay between G. lamblia and the experimental murine host.

Amino Acid Sequence↗
PubMed2001

Chasing coccidia--new tools enter the race.

The 8th International Coccidiosis Conference, held on 9--13 July 2001 in Palm Cove, Australia, was a showcase of the latest studies on widely known coccidia, including Eimeria and Toxoplasma in addition to the emerging or re-emerging parasites such as Neospora, Cryptosporidium and Cyclospora. This meeting was staged in conjunction with the Annual Scientific Meeting of the Australian Society for Parasitology.

Animals↗
PubMed2001

Geometry dependent two-dimensional heteronuclear multiplet effects in paramagnetic proteins.

We report experimental observation and numerical simulation of a two-dimensional multiplet effect in the heteronuclear correlation spectrum of a paramagnetic protein that depends on molecular geometry. This effect arises as a consequence of cross-correlated relaxation involving the Curie spin relaxation and internuclear dipolar relaxation mechanisms. It also manifests itself in resolution and sensitivity improvement in transverse relaxation optimised spectroscopy (TROSY) kind of experiments. Characteristic multiplet patterns in heteronuclear coupled two-dimensional NMR spectra encode directional information for the heteronuclear bond with respect to the paramagnetic center. These patterns, which are simulated here using Redfield's relaxation theory, can be used to obtain a new type of geometry restriction for structure determination and refinement of paramagnetic macromolecular systems.

Animals↗
PubMed2001

Evaluation of a concurrent multicomponent collection system for the collection and storage of WBC-reduced RBC apheresis concentrates.

BACKGROUND: Multicomponent apheresis procedures offer the possibility of collecting blood components that are standardized, as compared to those available with whole-blood donations. A new separator program for the concurrent collection of RBCs, platelets, and plasma (Amicus, Baxter Healthcare) was evaluated. STUDY DESIGN AND METHODS: Apheresis donors (n = 47) underwent concurrent collection of RBCs, platelets, and plasma by use of the single-needle procedure of the Amicus blood cell separator. A standardized RBC volume (100% Hct) of 200 mL was targeted with either 1 or 2 platelet concentrate units, depending on the donor's predonation characteristics. After collection, the RBC component was sterilely connected to an RBC collection set (Amicus) to allow for the addition of 100 mL of saline-adenine-glucose-mannitol preservative solution and WBC reduction at either ambient temperature or 4 degrees C. The RBC units were subsequently stored at 2 to 6 degrees C for 42 days, and the following in vitro measures were evaluated over the storage period: blood cell counts including Hct and total Hb, plasma Hb, potassium, pH, ATP, and 2,3 DPG. RESULTS: Procedure time averaged 74 +/- 9 minutes, and no adverse events were reported. The absolute RBC volume collected averaged 198 +/- 11 mL with an average Hct value of 83 +/- 2 percent. After filtration, the Hb content averaged 58.2 +/- 2.4 g per unit and residual WBCs averaged 0.038 +/- 0.015 x 10(6) per unit. Day 42 results showed that all units had on average more than 70-percent ATP maintenance, and all of the units had less than 0.8 percent he-molysis. All units had pH values higher than 6.5 on Day 42. CONCLUSION: The concurrent multicomponent collection system (Amicus) can reliably collect a standardized RBC unit of good quality. In vitro testing of the RBCs collected and stored for 42 days met the Council of Europe criteria for transfusion.

Adenosine Triphosphate↗
PubMed2001

Arm ability training for stroke and traumatic brain injury patients with mild arm paresis: a single-blind, randomized, controlled trial.

OBJECTIVE: To test the efficacy of the arm ability training (AAT) on a sample of patients with central arm paresis after traumatic brain injury (TBI) or stroke. DESIGN: Single-blind, randomized, controlled trial. SETTING: Inpatient rehabilitation center. PATIENTS: Consecutive sample of 74 patients of whom 60 (45 with stroke, 15 with TBI) completed the study; 37 patients received a 1-year follow-up. INTERVENTION: Daily AAT with (n = 20) or without (n = 20) knowledge of results, or no AAT (n = 20) during a 3-week intervention period. MAIN OUTCOME MEASURES: Summary time scores of the Test Evaluant les Membres superieurs des Personnes Agees (TEMPA)-a test of upper extremity function with daily function-like activities (focal disability)-and kinematic analysis of aimed movements. RESULTS: Patients with AAT realized superior improvement as compared with controls. Mean improvement in the time needed to perform (1) all TEMPA tasks was 41.4 versus 12.8 seconds (p =.0012); (2) unilateral TEMPA tasks, 16.5 versus 4.2 seconds (p =.0036); and (3) the ballistic component of aimed movements, 96 versus 20ms (p =.0115). Knowledge of result did not substantially modify these effects. A functional benefit existed at 1-year follow-up. CONCLUSION: The AAT reduces focal disability among stroke and TBI patients with mild central arm paresis.

Activities of Daily Living↗
PubMed2001

The Th2-hypothesis of schizophrenia: a strategy to identify a subgroup of schizophrenia caused by immune mechanisms.

Immunologic findings in schizophrenia have been described for decades, but it was not possible to identify a pathogen until now. Most of these studies report immune abnormalities in a group of the investigated patients, but a distinct subgroup of schizophrenia with immune-related pathology has still not been characterized. In this paper we have integrated the most important immunologic data in schizophrenia research and hypothesize a shift to Th2-like immune reactivity in a subgroup of schizophrenic patients. Besides the immunological abnormalities, this subgroup is further characterized by more pronounced negative symptoms and poor therapy outcome. There is evidence that this subgroup might be caused by a prenatal viral infection.

Humans↗
PubMed2001

vsp gene expression by Giardia lamblia clone GS/M-83-H7 during antigenic variation in vivo and in vitro.

Giardia lamblia infections are associated with antigenic variation of the parasite, which is generated by a continuous change of the variant-specific surface proteins (VSPs). Many investigations on the process of antigenic variation were based on the use of G. lamblia clone GS/M-83-H7, which expresses VSP H7 as its major surface antigen. In the present study, mice were infected with the aforementioned clonal line to investigate vsp gene expression during the complex process of antigenic variation of the parasite. Trophozoites collected from the intestines of individual animals at different time points postinfection (p.i.) were analyzed directly for their vsp gene expression patterns, i.e., without cultivating the recovered parasites in vitro. Because few trophozoites were recovered at late time points p.i., a combined 5' rapid amplification of cDNA ends-reverse transcription-PCR approach was utilized. This allowed detection and subsequent sequence analysis of vsp gene transcripts upon generation of amplified cDNA analogues. The same PCR approach was applied for analysis of vsp gene expression in variants obtained after negative selection of axenic GS/M-83-H7 trophozoites by treatment with a cytotoxic, VSP H7-specific monoclonal antibody. In an overall view of the entire panel of in vivo- and in vitro-derived parasite populations, expression of 29 different vsp gene sequences could be demonstrated. In vivo antigenic variation of G. lamblia clone GS/M-83-H7 was shown to be a continuous process involving the consecutive appearance of relatively distinct sets of vsp transcripts. During the 42-day infection period investigated, this process activated at least 22 different vsp genes. Comparative molecular analyses of the amino acid level demonstrated that all cDNA segments identified encode structural elements typical of the terminal segment of Giardia VSP. The similarity of most of the GS/M-83-H7 VSP sequences identified in the present study supports previous suggestions that vsp gene diversification in G. lamblia is the result of ancestral gene duplication, mutation, and/or recombination events.

Amino Acid Sequence↗
PubMed2000

Interaction of the G protein beta 3 subunit T825 allele and the IRS-1 Arg972 variant in type 2 diabetes.

BACKGROUND: Type 2 diabetes mellitus is a common late-onset disease with a strong genetic component. It is characterized by insulin resistance which results from alterations in insulin signal transduction. The G protein beta 3 subunit 825T allele was recently found to be associated with hypertension and obesity which makes it a sensible candidate gene for type 2 diabetes. METHODS: In a case-control study on 320 male patients and 962 male healthy controls we investigated the association of two candidate genes with diabetes, i.e. (i) the GNB3 825T allele, associated with a G protein beta 3 subunit splice variant and enhanced intracellular signal transduction, and (ii) the insulin receptor substrate-1 (IRS-1) 972Arg variant, which encodes a protein variant associated with cellular insulin resistance. RESULTS: The GNB3 825T allele and the IRS-1 972Arg variant were significantly associated with diabetes (odds ratios for either variant 1.4 1.8). Odds ratios were 3 4 in males carrying both alleles. CONCLUSIONS: The results document an association of a hypertension susceptibility gene with type 2 diabetes which may partially explain the frequent coexistence of both disorders.

Adult↗
PubMed2000

Assay of diverse protease activities on the basis of a small synthetic substrate.

The available methods for assaying of protease activity of unknown or partially defined specificity utilize long peptides, mostly denatured proteins, comprehending at least all coded amino acids in cleavable positions. In contrast, here we report on an alternative approach which utilizes a small synthetic ester substrate containing only one amino acid. The approach equally detects endo- and carboxypeptidases with a wide variety of specificities including enzymes specific for basic, acidic, aromatic, and nonaromatic hydrophobic amino acid moieties. The results further revealed that most proteases could be detected in activities considerably less than 1 U. In contrast to the methods used thus far, the enzymatic hydrolysis of the small substrate can be easily and rapidly assayed by a shift in absorption resulting in a change in color of the assay mixture at visible wavelengths. Thus, no additional instrumental efforts are generally required. On the basis of these characteristics, the approach presented here could be particularly valuable for monitoring the purification of enzymes or as a rapid check for protease activity.

Amino Acids↗
PubMed2000

Digitized analysis of abnormal hand-motor performance in schizophrenic patients.

Many studies have shown a high prevalence of discrete neuromotor disturbances in schizophrenic patients. It was hypothesized that these disturbances are lateralized and reflect a neurodevelopmental disorder underlying schizophrenia. A new method for assessing subtle motor dysfunction and hemispheric asymmetries is the registration of hand movements with a digitizing tablet. Using this method, we studied hand-motor dysfunction and its lateralization in schizophrenics, as compared with healthy controls. All subjects (27 schizophrenic patients, 13 of them without neuroleptic medication, the others under neuroleptics; 31 healthy controls) drew super-imposed concentric circles. We computed kinematic parameters reflecting velocity and automatization to quantify neurological soft signs (NSS). The patients had significant impairments of regularity of repetitive hand movements, as compared with the healthy controls (F> or =5.35; p< or =0.024(*)). Comparing differences of left- and right-hand performance between patients and controls, we found longer stroke duration (F=(15,98); p=0.000***) and decreased automatization (F=18,14; p=0.000***), especially on the left side in schizophrenic patients. Measuring hand movements with a digitizing tablet is a sensitive method for assessing subtle motor dysfunction in schizophrenic patients, not reflected in the scores of clinical scales. Our findings show NSS in schizophrenic patients, independently of neuroleptics. Further, the hypothesis of lateralization of cerebral structures generating NSS towards the right hemisphere in schizophrenia is supported.

Adult↗
PubMed2000

Isolation and characterization of an Achromobacter xylosoxidans strain B3 and other bacteria capable to degrade the synthetic chelating agent iminodisuccinate.

Three bacterial strains were isolated, which used the synthetic chelating agent iminodisuccinate (IDS) as sole carbon source for growth in mineral salts media (MSM). Taxonomic analysis and 16S rDNA sequence analysis identified one of these isolates (B3), which was isolated from sewage sludge, as a strain of Achromobacter xylosoxidans subsp. xylosoxidans. It exhibited a doubling time of approximately 3 h in liquid MSM supplemented with IDS and grew even in the presence of 1.0% (w/v) IDS. Since photometric and high performance liquid chromatography analysis showed that IDS, which came onto the market only recently as an alternative for ethylenediaminetetraacetate, was completely degraded by axenic cultures of bacteria; it will probably be readily degraded in the environment.

Alcaligenes↗
PubMed2000

Increased anti-streptococcal antibodies in patients with Tourette's syndrome.

Infection or postinfectious phenomena have been postulated to play a role in the pathogenesis of children afflicted with the typical symptoms of Tourette's syndrome (TS). We investigated whether an increase of titers of antistreptococcal antibodies can be reproduced in our children with TS, and whether this increase is restricted to children. We examined the titers of two different antistreptococcal antibodies, antistreptolysin (ASL) and anitDNase B, both in children and adults. Titer s of ASO and antiDNase B were measured (1) in 13 children/adolescents suffering from TS and in an aged-matched comparison group;(2) in 23 adult patients, a comparison group of 23 aged-matched controls, and in another group of 17 aged-matched, non-medicated acute schizophrenics. ASO and antiDNase B titers were determined by laser nephelometry using a commercially available kit. Two antistreptococcal cut-off levels were compared (> 250 U/ml and 400 U/ml). As expected, increases ASO titers (>400 IU/ml) were found in a higher portion of children/adolescents with TS compared to controls. Regarding adults, titers >250 U/ml for both antistreptococcal antigens were found in significantly more TS patients than in schizophrenic patients or healthy control subjects. The mean values of ASO and antiDNase titers were significantly higher in both groups of TS patients compared to control children/adolescents, to the comparison groups of healthy adults and to schizophrenics. No difference in antistreptococcal titers was found between schizophrenics and the group of healthy adults. TS patients exhibited higher antistreptococcal titers than age-matched comparison groups of both children/adolescents and adults using different types of calculation. Our findings support the theory that a postinfectious immune mechanism may play a role in the pathogenesis of TS. The mechanism still needs to be elucidated.

Adolescent↗
PubMed2000

Decreased levels of soluble intercellular adhesion molecule-1 (sICAM-1) in unmedicated and medicated schizophrenic patients.

BACKGROUND: The soluble intercellular adhesion molecule-1 (sICAM-1) is a marker for the activation of the cellular immune system. Since an activation of the immune system has been observed in a part of the schizophrenic patients, we measured the serum levels of soluble ICAM-1 (sICAM-1) in schizophrenic patients and correlated them to the patient's psychopathology. METHODS: To monitor a possible effect of antipsychotic therapy, 36 schizophrenic patients were examined twice: first without antipsychotic medication immediately after admission to the hospital and then, after clinical improvement before discharge. The results were compared with those of 36 age- and gender-related healthy individuals. RESULTS: The schizophrenic patients showed significantly decreased serum levels of sICAM-1 at the first examination (248 +/- 95 ng/mL) and at re-examination (266 +/- 95 ng/mL) compared with the comparison group (323 +/- 74 ng/mL). Patients with more pronounced negative symptoms showed higher levels of sICAM-1 at the first examination. CONCLUSIONS: We conclude that reduced sICAM-1 levels in schizophrenia indicate a reduced activity of the cellular immune system in at least a subgroup of schizophrenic patients.

Acute Disease↗
PubMed2000

Disability and quality of life in pure and comorbid social phobia. Findings from a controlled study.

Social phobia is increasingly recognized as a prevalent and socially impairing mental disorder. However, little data is available regarding the general and disease-specific impairments and disabilities associated with social phobia. Furthermore, most studies have not controlled for the confounding effects of comorbid conditions. This study investigates: (a) the generic quality of life; (b) work productivity; and, (c) various other disorder-specific social impairments in current cases with pure (n = 65), comorbid (n = 51) and subthreshold (n = 34) DSM-IV social phobia as compared to controls with no social phobia (subjects with a history of herpes infections). Social phobia cases reported a mean illness duration of 22.9 years with onset in childhood or adolescence. Current quality of life, as assessed by the SF-36, was significantly reduced in all social phobia groups, particularly in the scales measuring vitality, general health, mental health, role limitations due to emotional health, and social functioning. Comorbid cases revealed more severe reductions than pure and subthreshold social phobics. Findings from the Liebowitz self-rated disability scale indicated that: (a) social phobia affects most areas of life, but in particular education, career, and romantic relationship; (b) the presence of past and current comorbid conditions increases the frequency and severity of disease-specific impairments; and, (c) subthreshold social phobia revealed slightly lower overall impairments than comorbid social phobics. Past-week work productivity of social phobics was significantly diminished as indicated by: (a) a three-fold higher rate of unemployed cases; (b) elevated rates of work hours missed due to social phobia problems; and (c) a reduced work performance. Overall, these findings underline that social phobia in our sample of adults, whether comorbid, subthreshold, or pure was a persisting and impairing condition, resulting in considerable subjective suffering and negative impact on work performance and social relationships. The current disabilities and impairments were usually less pronounced than in the past, presumably due to adaptive behaviors in life style of the respondents. Data also confirmed that social phobia is poorly recognized and rarely treated by the mental health system.

Adult↗
PubMed2000

A pyrophosphate bridge links the pyruvate-containing secondary cell wall polymer of Paenibacillus alvei CCM 2051 to muramic acid.

The peptidoglycan, the secondary cell wall polymer (SCWP), and the surface layer (S-layer) glycoprotein are the major glycosylated cell wall components of Paenibacillus alvei CCM 2051. In this report, the complete structure of the SCWP, its linkage to the peptidoglycan layer, and its physicochemical properties have been investigated. From the combined evidence of chemical and structural analyses together with one- and two-dimensional nuclear magnetic resonance spectroscopy, the following structure of the SCWP-peptidoglycan complex is proposed: [(Pyr4,6)-beta-D-ManpNAc-(1-->4)-beta-D-GlcpNAc-(1-->3)]n-11-(Pyr4,6)-beta-D-ManpNAc-(1-->4)-alpha-D-GlcpNAc-(1-->O)-PO2-O-PO2-(O-->6)-MurNAc- Each disaccharide unit is substituted by 4,6-linked pyruvic acid residues. Under mild acidic conditions, up to 50% of them are lost, leaving non-substituted ManNAc residues. The anionic glycan chains constituting the SCWP are randomly linked via pyrophosphate groups to C-6 of muramic acid residues of the peptidoglycan layer. 31P NMR reveals two signals that, as a consequence of micelle formation, experience different line broadening. Therefore, their integral ratio deviates significantly from 1:1. By treatment with ethylenediaminetetraacetic acid, sodium dodecyl sulfate, and sonication immediately prior to NMR measurement, this ratio approaches unity. The reversibility of this behavior corroborates the presence of a pyrophosphate linker in this SCWP-peptidoglycan complex. In addition to the determination of the structure and linkage of the SCWP, a possible scenario for its biological function is discussed.

Bacillus↗