Complex structural dynamics of nanocatalysts revealed in Operando conditions by correlated imaging and spectroscopy probes.

Understanding how heterogeneous catalysts change size, shape and structure during chemical reactions is limited by the paucity of methods for studying catalytic ensembles in working state, that is, in operando conditions. Here by a correlated use of synchrotron X-ray absorption spectroscopy and scanning transmission electron microscopy in operando conditions, we quantitatively describe the complex structural dynamics of supported Pt catalysts exhibited during an exemplary catalytic reaction-ethylene hydrogenation. This work exploits a microfabricated catalytic reactor compatible with both probes. The results demonstrate dynamic transformations of the ensemble of Pt clusters that spans a broad size range throughout changing reaction conditions. This method is generalizable to quantitative operando studies of complex systems using a wide variety of X-ray and electron-based experimental probes.

Surface layering at the mercury-electrolyte interface.

X-ray reflectometry reveals atomic layering at a liquid-liquid interface--mercury in a 0.01 M NaF solution. The interface width exceeds capillary wave theory predictions and displays an anomalous dependence on the voltage applied across it, displaying a minimum positive of the potential of zero charge. The latter is explained by electrocapillary effects and an additional intrinsic broadening of the interface profile, tentatively assigned to polarization of the conduction electrons due to the electric field of the electrochemical double layer at the interface.

AMF-induced biocontrol against plant parasitic nematodes in Musa sp.: a systemic effect.

Although mycorrhizal colonization provides a bioprotectional effect against a broad range of soil-borne pathogens, including plant parasitic nematodes, the commercial use of arbuscular mycorrhizal fungi (AMF) as biocontrol agents is still in its infancy. One of the main reasons is the poor understanding of the modes of action. Most AMF mode of action studies focused on AMF-bacterial/fungal pathogens. Only few studies so far examined AMF-plant parasitic nematode interactions. Therefore, the aim of the study was to determine whether the AMF Glomus intraradices was able to incite systemic resistance in banana plants towards Radopholus similis and Pratylenchus coffeae, two plant parasitic nematodes using a split-root compartmental set-up. The AMF reduced both nematode species by more than 50%, even when the AMF and the plant parasitic nematodes were spatially separated. The results obtained demonstrate for the first time that AMF have the ability to induce systemic resistance against plant parasitic nematodes in a root system.

Aseptic Culture Systems of Radopholus similis for In Vitro Assays on Musa spp. and Arabidopsis thaliana.

Radopholus similis is one of the most damaging nematodes in bananas. Chemical control is currently the most-used method, but nematode control through genetic improvement is widely encouraged. The objective of this study was to establish an aseptic culture system for R. similis and determine whether R. similis can infect and reproduce on in vitro banana plantlets and in vitro Arabidopsis thaliana. In the study's first part, a suitable aseptic culture system was developed using alfalfa callus. Radopholus similis could penetrate and reproduce in the callus. Six weeks after inoculation with 25 females, the reproduction ratio was 26.3 and all vermiform stages were present. The reproduction ratio increased to 223.2 after 12 weeks. Results of a greenhouse test showed that R. similis did not lose its pathogenicity after culturing on alfalfa callus. In the study's second part, the infection and reproduction of the nematodes cultured on the callus were studied on both in vitro banana plantlets and A. thaliana. Radopholus similis infected and reproduced on both banana and A. thaliana. Furthermore, nematode damage was observed in the root systems of both hosts. These successful infections open new perspectives for rapid in vitro screening for resistance in banana cultivars and anti-nematode proteins expressed in A. thaliana.

Construction and sequencing of new derivatives of the pIN-III-ompA secretion vector.

The growing interest in proteins exported by bacteria led to the development of cloning vectors designed for targeting recombinant proteins to extracytoplasmic compartments. The pIN-III-ompA vector family fulfils such a function. Here we report the construction and sequencing of new pIN-III-ompA derivatives with alternate polylinker sites, increasing the cloning flexibility of these vectors.

Colorimetric solid-phase capture hybridization assay for detection of amplified Borrelia burgdorferi DNA.

To simplify detection procedures of DNA fragments resulting from PCR, we developed a colorimetric microplate hybridization assay. This format was used for the identification of Borrelia burgdorferi sensu lato, the causal agent of Lyme disease. The system relied on the use of a specific capture probe covalently linked to polystyrene plates and a specific polybiotinylated detection probe. DNA fragments, resulting from PCR and sandwiched between these two probes, were detected by enzymatic color development. The new detection format outperformed agarose gel electrophoresis of PCR products in sensitivity and specificity Moreover, in view of its rapidity and simplicity, the system proved appropriate for the routine diagnostic analysis of clinical specimens from Lyme disease patients. The proposed detection format can be adapted easily to other DNA targets and is suitable for automation.

alpha-L-fucosidase in human fibroblasts. I. The enzyme activity polymorphism.

Low plasma alpha-L-fucosidase activity is a recessive polymorphic trait observed in 8% of the normal population. The molecular basis of this polymorphism remains unclear and its expression is tissue specific. As the low-activity (variant) phenotype is expressed in vitro in cultured human fibroblasts, this cell type was chosen to study the enzyme activity polymorphism. Fibroblast cell lines derived from individuals with low plasma fucosidase activity (variants) have less than 30% of the fucosidase activity of fibroblast cell lines established from individuals with high plasma fucosidase activity (nonvariants). No qualitative differences in the synthesis, processing, and extracellular release of newly made alpha-L-fucosidase could be demonstrated among variant and nonvariant cell strains. Cells pulsed with 3H-leucine for 10 min produce a 51-kDa protein which is rapidly processed to a 55-kDa intermediate. The latter is converted to a mature 59-kDa intracellular and a 61-kDa extracellular end product, in both variant and nonvariant fibroblast cell lines. Variant and nonvariant fibroblast cell lines also release relatively equal amounts of fucosidase into the extracellular medium. Therefore, differences in processing or extracellular release of fucosidase between variants and nonvariants are not the basic mechanism of this tissue-specific activity polymorphism.

Globoid cell leukodystrophy: a family with both late-infantile and adult type.

We present a patient with adult-onset globoid cell leukodystrophy (GBL) who had almost complete deficiency of galactosylceramide beta-galactosidase. A brother of the index patient deteriorated neurologically and died at the age of 4, probably from the late-infantile form of the disease. In this family, two clinical types of GBL are probably different expressions of an identical genotype.

[Rheumatologic and radiologic symptoms of secondary hyperparathyroidism: retrospective long-term study of 175 chronic hemodialysis patients]. / Rheumatologische und radiologische Symptome des sekundären Hyperparathyreoidismus: Retrospektive Langzeitstudie an 175 chronischen Hämodialysepatienten.

Despite recent improvements of hemodialysis (HD) techniques, symptoms due to secondary hyperparathyroidism (HPT) contribute to longtime complications of HD patients. The aim of the present retrospective study was to determine the incidence and localization of radiological joint and bone lesions in 175 patients on chronic HD. In 108 patients the diagnosis of HPT was made by radiologic criteria. 56% had radiomorphologic lesions of the hands, 45% of the acromio-clavicular (AC) joint, 31% of the shoulder, and 27% of the pelvis. No sex difference was found for prevalence of HPT in these patients, nor was one found for any of the underlying renal diseases. There was a negative correlation between elevated serum parathyroid hormone and serum aluminum concentrations. In 111 patients the history of bone and joint pain was evaluated. 54% of these patients suffered from bone pain, arthralgia, and morning stiffness. Radiological lesions of AC-joint correlated with shoulder pain in 38%. Our data show that even in the predialytic phase of renal insufficiency x-rays of the shoulder are helpful in early diagnosis of HPT. Skeletal manifestations specific for one of the underlying renal diseases do not exist. Elevated PTH levels are a good indicator of HPT in these patients, whereas low levels of PTH do not exclude radiological manifestations. In contrast to beta 2-microglobulin amyloidosis, pain does not occur during rest and is not worsened during HD. Treatment with non-steroidal antiinflammatory drugs led to pain relief in the majority of patients. Pain history in patients on chronic HD provides important information concerning the differential diagnosis of HPT/beta 2-microglobulin amyloidosis.

Detection of Borrelia burgdorferi in biological samples using the polymerase chain reaction assay.

Oligonucleotide primers were used in the polymerase chain reaction assay to amplify specific DNA regions of the Borrelia burgdorferi 49-kb linear plasmid. One set of primers identifies a 442-bp DNA fragment in the OspA gene and a second pair of amplimers, a 176-bp DNA piece located in the OspB gene. The last set of primers, OspBpc3/pc4, outperformed the other pair in discriminating pathogenic North American or European isolates from related bacterial species, detected down to 4 spirochaetes, and was suitable for the identification of B. burgdorferi in biological samples, such as synovial and cerebrospinal fluids.

Frequency of the phenylalanine deletion (delta F508) in the CF gene of Belgian cystic fibrosis patients.

Cloning and sequencing of the CF gene has identified a three-base-pair deletion (delta F508) responsible for CF in the majority of CF patients (Kerem et al. 1989). We have used the polymerase chain reaction with oligonucleotide primers bridging the delta F508 deletion to analyze the presence or absence of this mutation in the Belgian CF population. The delta F508 mutation was present in 80% (57 on 71) of CF chromosomes from 36 unrelated Belgian CF families from the region of Antwerp. This mutation was associated with haplotype B for the KM.19-XV-2c RFLPs as 93% (53 on 57) of the CF chromosomes with the delta F508 mutation carried haplotype B.

Specific identification of Mycobacterium leprae by the polymerase chain reaction.

Oligonucleotide primers have been used to amplify DNA regions of the M. leprae genome by the polymerase chain reaction. A first set of primers, PLp1 and PLp2, identifies a specific 386 bp DNA fragment located in the gene coding for the 65 kDa antigen of M. leprae. A second pair of primers, targetted to the same gene, leads to the amplification of a 154 bp DNA piece conserved in mycobacteria. Primers PLp1 and PLp2 discriminate the pathogenic species from other mycobacteria, detect down to 40 bacilli, and constitute potentially useful tools for the identification of M. leprae in clinical specimens.

Linkage of DNA markers at Xq28 to adrenoleukodystrophy and adrenomyeloneuropathy present within the same family.

We present a large kindred that contained patients with either adrenoleukodystrophy (ALD) or adrenomyeloneuropathy (AMN). The pedigree clearly supported the X-linked mode of inheritance of the nonneonatal form of ALD/AMN. Analysis with DNA markers at Xq28 suggested segregation of both ALD and AMN with an identical haplotype. This indicated that nonneonatal ALD and AMN are caused by a mutation in the same gene at Xq28. It showed, furthermore, that phenotypic differences between ALD and AMN are not necessarily the consequence of allelic heterogeneity due to different mutations within the same gene. The maximal lod score for linkage of the ALD/AMN gene and the multiallelic anonymous DNA marker at DXS52 was 3.0 at a recombination fraction of 0.00. This made a prenatal or presymptomatic diagnosis and heterozygote detection by DNA analysis with this marker reliable.