Biomedical subjects

A Willems

Publications and source records attributed to A Willems.

At least 19 recordsLinked to original sources

PubMed2006

The effect of rhythmic somatosensory cueing on gait in patients with Parkinson's disease.

BACKGROUND AND AIMS: Gait and gait related activities in patients with Parkinson's disease (PD) can be improved with rhythmic auditory cueing (e.g. a metronome). In the context of a large European study, a portable prototype cueing device was developed to provide an alternative for rhythmic auditory cueing: rhythmic somatosensory cueing (RSC, a miniature vibrating cylinder attached to the wrist). We investigated whether PD patients could adapt their walking pattern using RSC under conditions of changing walking speed and the presence of potentially distracting visual flow while walking on a treadmill. METHODS: A total of 17 patients with PD participated (mean age 63.4+/-10.3 years; Hoehn-Yahr score 2.5+/-0.9, mean Unified Parkinson's Disease Rating Scale score 49.8+/-13.7, mean disease duration 7.7+/-5.1 years). They performed systematic walking speed manipulations under 4 conditions in a random order: (1) no cue, no visual flow, (2) no cue, visual flow, (3) cue, no visual flow and (4) cue, visual flow. Visual flow in the form of a virtual corridor that moved at the current walking speed was projected on a 2 x 2 m rear-projection screen. The cueing rhythm was set at -10% of preferred stride frequency at each speed. Stride frequency was assessed using peaks in the trajectories of thigh sagittal plane segmental angles. RESULTS: Walking with RSC resulted in lower stride frequencies, and thus larger step lengths (p-values <0.05), regardless of walking speed. The presence of visual flow did not impair the use of RSC, as evidenced by the lack of differences between conditions 3 and 4 (p>0.05). CONCLUSION: Rhythmic somatosensory cueing may be a viable alternative for auditory cueing and is robust to changes in walking speed and visual distractors.

Aged↗

PubMed2006

The role of the testis-specific gene hTAF7L in the aetiology of male infertility.

The X-linked TAF7L gene is homologous to the autosomal transcription factor TAF7. Together with its testis-specific expression pattern, this might point to an important function in spermatogenesis. In order to analyse the involvement of the hTAF7L gene in the aetiology of male infertility, a total of 25 patients with maturation arrest of spermatogenesis have been analysed for the presence of mutations in this gene. Four alterations of the nucleotide sequence, with concomitant changes in the amino acid sequence, have been observed in 12 patients. All sequence alterations were also found either in a control group consisting of men with proven fertility or in a control group with men with normal spermatogenesis. Therefore, these alterations are probably polymorphisms.

Amino Acid Sequence↗

PubMed2006

Fatal illness associated with pulmonary hypertension in a neonate caused by intrauterine echovirus 11 infection.

Nonpolio enterovirus (NPEV) infections are known to cause a wide range of illnesses in the neonatal period. In most cases, NPEV is presumed to be contracted during birth. Intrauterine NPEV infections occur infrequently. A case of intrauterine echovirus 11 infection with pneumonia, persistent pulmonary hypertension of the newborn, and purpura fulminans is presented.

Echovirus Infections↗

PubMed2006

Phenotypical and genotypical characteristics of root-nodulating bacteria isolated from annual Medicago spp. in Soummam Valley (Algeria).

AIMS: In the framework of agro-pastoral system management using local annual medics coupled with their native root-nodulating bacteria to extend pasture zones, increase forage yields and improve ovine and bovine breeding in Algeria, we investigated diversity of rhizobia from annual Medicago spp. (Medicago arabica, Medicago polymorpha, Medicago minima and Medicago orbicularis). METHODS AND RESULTS: Ten nodulating-isolates were characterized by morphological, cultural, physiological and biochemical features, SDS-PAGE analysis and PCR-RFLP of 16S rDNA. The results show some degree of genetic diversity among the isolates; three can be affiliated to Sinorhizobium meliloti, one to Rhizobium galegae and six were separate. CONCLUSIONS: Local annual medics would have a high degree of specificity in their symbiotic interaction. Furthermore, our results support the presence of Rh. galegae in the Mediterranean region. SIGNIFICANCE AND IMPACT OF THE STUDY: This work is a preliminary step towards selection of efficient symbiotic Medicago-rhizobia to develop inoculants for management of agro-pastoral systems using local annual medics in Algeria.

Algeria↗

PubMed2006

Application of intrathecal trastuzumab (Herceptintrade mark) for treatment of meningeal carcinomatosis in HER2-overexpressing metastatic breast cancer.

Leptomeningeal carcinomatosis represents a rare manifestation of metastatic breast cancer (MBC). A 39-year-old female presenting with HER2-overexpressing MBC and suffering from meningeal carcinomatosis was treated with the humanized antibody trastuzumab directed to HER2 by intrathecal administration. The patient was diagnosed with HER2-overexpressing stage III breast cancer in December 2003. In August 2004, the patient developed a singular intracerebral metastasis which was resected by neurosurgery followed by whole-brain radiotherapy. Since MRI and cerebrospinal fluid (CSF) analyses indicated meningeal carcinomatosis, the patient was commenced on trastuzumab (6 mg/kg q3w) and capecitabine (2.500 mg/m2 d1-14, q3w). Prompted by clinical deterioration, 5 repeated doses of intrathecal methotrexate (15 mg/dose) were administered, yet without clinical improvement. There is initial evidence that trastuzumab does not reach an adequate concentration in CSF after intravenous application. Nevertheless, infiltration of trastuzumab into CSF is facilitated under conditions of an impaired blood-brain barrier, as it is known for meningeal carcinomatosis. For patients with leptomeningeal disease, intrathecal application of trastuzumab may provide an interesting therapeutical approach for patients with HER2 overexpressing metastatic breast cancer. Therefore, an Ommaya reservoir for intrathecal treatment with trastuzumab was placed surgically and intrathecal therapy was begun with escalating doses of trastuzumab (5-20 mg), which proved to be effective and well tolerated by the patient. Within 2 weeks after treatment, the patients' condition improved significantly and cell counts in CSF obtained from the Ommaya reservoir remained low for 11 months after first diagnosis of meningeal carcinomatosis when clinical symptoms and MRI indicated progression of meningeal and cerebral disease.

Adult↗

PubMed2005

The effects of visual rhythms and optic flow on stride patterns of patients with Parkinson's disease.

This study was aimed at determining the effects of rhythmic visual cueing under changing visual conditions on stride frequency in patients with Parkinson's disease (PD; n = 21) and healthy age matched controls (n = 7) while walking at different speeds on a treadmill. Stride frequency and stride length in patients with PD as well as controls were not rigidly coupled to walking speed and could be manipulated with walking speed as well as by using spatial and temporal rhythmic visual cues.

Aged↗

PubMed2005

Effects of external rhythmical cueing on gait in patients with Parkinson's disease: a systematic review.

OBJECTIVE: To critically review studies evaluating the effects of external rhythmical cueing on gait in patients with Parkinson's disease. METHODS: Articles published from 1966 to January 2005 were searched by two physiotherapists in MEDLINE, PiCarta, PEDRo, Cochrane, DocOnline, CINAHL and SUMSEARCH. To be included, articles had to investigate the effects of external rhythmical cueing (i.e., auditory, visual or tactile cueing) on gait parameters in patients with idiopathic Parkinson's disease. Both controlled and noncontrolled studies were included. Based on the type of design and methodological quality a meta-analysis or best-evidence synthesis was applied. RESULTS: Twenty-four studies (total number of patients = 626) out of the 159 screened studies were evaluated in this systematic review. Two out of 24 were randomized controlled trails (RCT), both of high methodological quality. One RCT did not focus specifically on external rhythmical cueing of individual patients with Parkinson's disease, but on group exercises in general, including walking with cues. All other studies were pre-experimental studies. Best-evidence synthesis showed strong evidence for improving walking speed with the help of auditory cues. Insufficient evidence was found for the effectiveness of visual and somatosensory cueing. CONCLUSION: Only one high-quality study, specifically focused on the effects of auditory rhythmical cueing, suggesting that the walking speed of patients with Parkinson's disease can be positively influenced. However, it is unclear whether positive effects identified in the laboratory can be generalized to improved activities of daily living (ADLs) and reduced frequency of falls in the community. In addition, the sustainability of a cueing training programme remains uncertain.

Acoustic Stimulation↗

PubMed2004

The interferon gamma secretion assay: a reliable tool to study interferon gamma production at the single cell level.

Different single-cell analyses for the detection of antigen-specific T cells based on antigen-triggered induction of cytokine production (elispot, intracellular cytokine staining, cytokine secretion assay, etc.) have been analyzed. In this paper we present the data of a thorough validation of the IFNgamma Secretion Assay (ISA, Miltenyi Biotec, Bergisch Gladbach, Germany). In this assay the secreted IFNgamma is bound to the cell surface and is then stained as an artificial surface molecule and analyzed by flow-cytometry. The introduction of five quality criteria markedly improved the reproducibility of this assay and made it very reliable (intra-assay variability<5%; inter-assay variability<20%). Recovery experiments further demonstrated that almost 100% of IFNgamma(+) labeled cells could be detected by this technology. In order to analyze which cell subsets contribute to IFNgamma-production, we compared the results obtained in different individuals after VZAg-stimulation. Three different IFNgamma-secretion patterns could be discerned. In Pattern 1 there is a predominant and almost equal contribution of T cells and NK cells with a minor contribution of CD3(+)CD56(+) and B cells. Pattern 2, which is most abundant, is characterized by a predominance of NK cells (60-70%). Pattern 3 differs from the previous one in its minor contribution of NK cells. Here T cells predominate the IFNgamma secretion. These results clearly demonstrate that the IFNgamma(+) subset distribution after VZAg-stimulation is not uniform and differs individually. Furthermore, the ISA-technology proves to be very useful in vaccine research. This was demonstrated by testing the IFNgamma(+) secretion pattern after HBsAg-stimulation in PBMC from HBsAg-vaccinated individuals.

Antibodies, Viral↗

PubMed2002

Distribution of genes encoding the trypsin-dependent lantibiotic ruminococcin A among bacteria isolated from human fecal microbiota.

Fourteen bacterial strains capable of producing a trypsin-dependent antimicrobial substance active against Clostridium perfringens were isolated from human fecal samples of various origins (from healthy adults and children, as well as from adults with chronic pouchitis). Identification of these strains showed that they belonged to Ruminococcus gnavus, Clostridium nexile, and Ruminococcus hansenii species or to new operational taxonomic units, all from the Clostridium coccoides phylogenetic group. In hybridization experiments with a probe specific for the structural gene encoding the trypsin-dependent lantibiotic ruminococcin A (RumA) produced by R. gnavus, seven strains gave a positive response. All of them harbored three highly conserved copies of rumA-like genes. The deduced peptide sequence was identical to or showed one amino acid difference from the hypothetical precursor of RumA. Our results indicate that the rumA-like genes have been disseminated among R. gnavus and phylogenetically related strains that can make up a significant part of the human fecal microbiota.

Bacteria↗

PubMed2001

A new model for intermediate molecular weight recombinant bispecific and trispecific antibodies by efficient heterodimerization of single chain variable domains through fusion to a Fab-chain.

Due to their specificity and versatility in use, bispecific antibodies (BsAbs) are promising therapeutic tools in tomorrow's medicine, provided sufficient BsAb can be produced. Expression systems favoring efficient heterodimerization of intermediate-sized bispecific antibodies will significantly improve existing production methods. Recombinant BsAb can be made by fusing single chain variable fragments (scFv) to a heterodimerization domain. We compare the efficiency of the isolated CL and CH1 constant domains with complete Fab chains to drive heterodimerization of BsAbs in mammalian cells. We found that the isolated CL:CH1 domain interaction was inefficient for secretion of heterodimers. However, when the complete Fab chains were used, secretion of a heterodimerized bispecific antibody was successful. Since the Fab chain encodes a binding specificity on its own, bispecific (BsAb) or trispecific (TsAb) antibodies can be made by C-terminal fusion of scFv molecules to the L or Fd Fab chains. This gave rise to disulphide stabilized Fab-scFv BsAb (Bibody)or Fab-(scFv)2 TsAb (Tribody) of intermediate molecular size. Heterodimerization of the L and Fd-containing fusion proteins was very efficient, and up to 90% of all secreted antibody fragments was in the desired heterodimerized format. All building blocks remained functional in the fusion product, and the bispecific character of the molecules as well as the immunological functionality was demonstrated.

Alkaline Phosphatase↗

PubMed2001

Differences between subcultures of the Mesorhizobium loti type strain from different culture collections.

Because of differences in the reported 16S rRNA gene sequence of the Mesorhizobium loti type strain available from different culture collections, we collected different subcultures of this strain and compared them by 16S rDNA sequencing, SDS-PAGE of whole-cell protein extracts and RAPD-PCR. Our results indicate that the 16S rDNA sequence differences can be explained by the presence of two different organisms in one of the subcultures. In addition, even for subcultures of the type strain that had identical 16S rDNA sequences, small differences could be observed in the protein profiles and in the RAPD-PCR patterns. These latter observations indicate that maintenance procedures necessary for long-term preservation by freeze-drying can cause subcultures of the same original strain to undergo changes, effectively leading to different fingerprints even though 16S rDNA sequences remain identical.

DNA Fingerprinting↗

PubMed2001

Phylogenetic and DNA-DNA hybridization analyses of Bradyrhizobium species.

The 16S rDNA sequence of Bradyrhizobium liaoningense was determined and analysed together with sequences of other Bradyrhizobium species and related taxa. In addition, DNA-DNA hybridizations were performed between representative strains of the three Bradyrhizobium species. Bradyrhizobium liaoningense is genotypically highly related to Bradyrhizobium japonicum, whereas Bradyrhizobium elkanii is more distantly related to these two species. The fact that Afipia, Agromonas, Blastobacter, Nitrobacter and Rhodopseudomonas are phylogenetically more closely related to Bradyrhizobium japonicum than to Bradyrhizobium elkanii is discussed.

Base Composition↗

PubMed2001

Comparison of sequence analysis of 16S-23S rDNA spacer regions, AFLP analysis and DNA-DNA hybridizations in Bradyrhizobium.

The sequences of the 16S-23S rDNA intergenic spacer region of 62 strains of Bradyrhizobium, including representatives of the three valid species, were determined. The majority of strains had a single rRNA operon type and all contained a tRNA(Ala) and a tRNA(Ile) gene. Analysis of the sequence data produced groupings in line with previously obtained AFLP data. DNA-DNA hybridizations were performed to determine to what extent spacer sequences and AFLP profiles reflected the overall genomic similarities. Strains belonging to the same AFLP group, and strains with spacer sequences diverging less than 4%, were found to belong to the same genospecies. More remote relationships (DNA homology levels of 40-60%) between species were reflected in the spacer sequence analysis, but not in the AFLP analysis. For the genus Bradyrhizobium, 16S-23S rDNA spacer sequence analysis provides taxonomic information similar, but not always identical to that obtained by DNA-DNA hybridizations. Our results indicate that this genus consists of a group of four highly related genospecies (Bradyrhizobium japonicum, Bradyrhizobium liaoningense and two other genospecies) and at least three other genospecies, one of which is Bradyrhizobium elkanii.

Bradyrhizobium↗

PubMed2001

Mesorhizobium chacoense sp. nov., a novel species that nodulates Prosopis alba in the Chaco Arido region (Argentina).

Low-molecular-weight RNA analysis was performed for the identification and classification of 20 Argentinian strains isolated from the root nodules of Prosopis alba. SDS-PAGE of total cellular proteins, determination of the DNA base composition, DNA-DNA reassociation experiments and physiological and biochemical tests were also carried out for these strains and the whole 16S rRNA gene was sequenced from one of the strains, strain LMG 19008T. Results of the genotypic and phenotypic characterization showed that the strains isolated in this study belong to a group that clustered in the genus Mesorhizobium. The results of DNA-DNA hybridizations showed that this group is a novel species of this genus. The name Mesorhizobium chacoense sp. nov. is proposed for this species. The type strain is LMG 19008T (= CECT 5336T).

Anti-Bacterial Agents↗

PubMed2001

Burkholderia fungorum sp. nov. and Burkholderia caledonica sp. nov., two new species isolated from the environment, animals and human clinical samples.

A polyphasic taxonomic study that included DNA-DNA hybridizations, DNA base ratio determinations, 16S rDNA sequence analyses, whole-cell protein and fatty acid analyses and an extensive biochemical characterization was performed on 16 strains isolated from the environment, animals and human clinical samples. The isolates belonged to the genus Burkholderia, were phylogenetically closely related to Burkholderia graminis, Burkholderia caribensis and Burkholderia phenazinium and had G+C contents between 61.9 and 62.2 mol%. Seven strains isolated from the rhizosphere were assigned to Burkholderia caledonica sp. nov. [type strain LMG 19076T (= CCUG 42236T)]. Nine strains isolated from the environment, animals and human clinical samples were assigned to Burkholderia fungorum sp. nov. [type strain LMG 16225T (= CCUG 31961T)]. Differential tests for B. graminis, B. caribensis, B. phenazinium, B. caledonica and B. fungorum include the following: assimilation of trehalose, citrate, DL-norleucine, adipate and sucrose; nitrate reduction; growth in the presence of 0.5% NaCl; and beta-galactosidase activity.

Animals↗

PubMed2001

DNA-DNA hybridization study of Bradyrhizobium strains.

DNA-DNA hybridizations were performed between Bradyrhizobium strains, isolated mainly from Faidherbia albida and Aeschynomene species, as well as Bradyrhizobium reference strains. Results indicated that the genus Bradyrhizobium consists of at least 11 genospecies, I to XI. The genospecies formed four subgeneric groups that were more closely related to each other (>40% DNA hybridization) than to other genospecies (<40% DNA hybridization): (i) genospecies I (Bradyrhizobium japonicum), III (Bradyrhizobium liaoningense), IV and V; (ii) genospecies VI and VIII; (iii) genospecies VII and IX; and (iv) genospecies II (Bradyrhizobium elkanii), X and XI. Photosynthetic Aeschynomene isolates were found to belong to at least two distinct genospecies in one subgeneric group. DNA-DNA hybridization data are compared with data from amplified fragment length polymorphism analysis and 165-23S rDNA spacer sequence analysis.

Bradyrhizobium↗

PubMed2001

Methylotrophic Methylobacterium bacteria nodulate and fix nitrogen in symbiosis with legumes.

Rhizobia described so far belong to three distinct phylogenetic branches within the alpha-2 subclass of Proteobacteria. Here we report the discovery of a fourth rhizobial branch involving bacteria of the Methylobacterium genus. Rhizobia isolated from Crotalaria legumes were assigned to a new species, "Methylobacterium nodulans," within the Methylobacterium genus on the basis of 16S ribosomal DNA analyses. We demonstrated that these rhizobia facultatively grow on methanol, which is a characteristic of Methylobacterium spp. but a unique feature among rhizobia. Genes encoding two key enzymes of methylotrophy and nodulation, the mxaF gene, encoding the alpha subunit of the methanol dehydrogenase, and the nodA gene, encoding an acyltransferase involved in Nod factor biosynthesis, were sequenced for the type strain, ORS2060. Plant tests and nodA amplification assays showed that "M. nodulans" is the only nodulating Methylobacterium sp. identified so far. Phylogenetic sequence analysis showed that "M. nodulans" NodA is closely related to Bradyrhizobium NodA, suggesting that this gene was acquired by horizontal gene transfer.

Acyltransferases↗

PubMed2000

Fab chains as an efficient heterodimerization scaffold for the production of recombinant bispecific and trispecific antibody derivatives.

Due to their multispecificity and versatility, bispecific Abs (BsAbs) are promising therapeutic tools in tomorrow's medicine. Especially intermediate-sized BsAbs that combine body retention with tissue penetration are valuable for therapy but necessitate expression systems that favor heterodimerization of the binding sites for large-scale application. To identify heterodimerization domains to which single-chain variable fragments (scFv) can be fused, we compared the efficiency of heterodimerization of CL and CH1 constant domains with complete L and Fd chains in mammalian cells. We found that the isolated CL:CH1 domain interaction was inefficient for secretion of heterodimers. However, when the complete L and Fd chains were used, secretion of L:Fd heterodimers was highly successful. Because these Fab chains contribute a binding moiety, C-terminal fusion of a scFv molecule to the L and/or Fd chains generated BsAbs or trispecific Abs (TsAbs) of intermediate size (75-100 kDa). These disulfide-stabilized bispecific Fab-scFv ("bibody") and trispecific Fab-(scFv)(2) ("tribody") heterodimers represent up to 90% of all secreted Ab fragments in the mammalian expression system and possess fully functional binding moieties. Furthermore, both molecules recruit and activate T cells in a tumor cell-dependent way, whereby the trispecific derivative can exert this activity to two different tumor cells. Thus we propose the use of the disulfide-stabilized L:Fd heterodimer as an efficient platform for production of intermediate-sized BsAbs and TsAbs in mammalian expression systems.

Adjuvants, Immunologic↗