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PubMed1981

Intracellular spiral inclusions in cerebral cell processes in Creutzfeldt-Jakob disease.

Electron microscopic examination of brain biopsy specimens from two patients with Creutzfeldt-Jakob disease revealed the presence of intracellular membranous spiral inclusions in the processes of cortical cells. These inclusions, 375 nm to 660 nm in length and 50 nm to 88 nm in width, resemble similar structures reported in a patient with the same disease by Bastian and, more recently, in a second patient by Gray et al. These inclusions bear close morphologic resemblance to spiroplasma organisms, a wall-free prokaryote known to cause a "slow-virus"-like disorder in mice.

Biopsy↗
PubMed1981

General principles of laboratory diagnosis of mycoplasma infections.

Laboratory diagnosis includes 1) methods for direct microscopic demonstration of mycoplasma cells and antigens in animal and plant tissues or excreta, and cell cultures, 2) methods for isolation and growth of mycoplasmas from the said sources, and 3) techniques for identification and classification of mycoplasma isolates by a) determination of biochemical characteristics, and b) serological tests. A great many techniques are available for each of these purposes. Some of them have been used routinely for several years. Other methods that appeared promising when they were first introduced have never obtained general usage or they have more limited applications. Pertinent techniques will be reviewed and described. For demonstration of mycoplasmas in tissues, particular emphasis will be placed on immunofluorescence and immunoperoxidase tests. Attempts at isolation and cultivation of mycoplasmas should take into consideration the source, collection and transport of materials, elimination of growth-inhibiting factors in animals and plant tissues, special growth requirements of mycoplasmas, and the importance of cloning of cultures as a preliminary to further characterization. Although a number of biochemical tests are available for general characterization of mycoplasma isolates, precise identification of the species can usually be made only by serological techniques. For that purpose, growth inhibition, immunofluorescence, and (in the case of spiroplasmas) the deformation test combine the advantages of being highly specific and relatively easy to perform, and hence have obtained most widespread usage.

Antibodies, Bacterial↗
PubMed1997

The Echigo-1: a panencephalopathic strain of Creutzfeldt-Jakob disease: a passage to hamsters and ultrastructural studies.

The Echigo-1 strain of Creutzfeldt-Jakob disease (CJD) was isolated by Mori and colleagues (1989) from a case of a 33-year-old female with a panencephalopathic type of CJD. We report here ultrastructural data on the first passage in this laboratory. The bulk of the lesions was localized to the brain stem and cervical cord. Neuropathology was extraordinarily florid but quantitatively not much different from that reported for other panencephalopathic model of CJD, the Fujisaki (Fakuoka-1) strain of CJD passaged in NIH Swiss mice. Two types of vacuoles were easy to discriminate: typical change and intramyelin vacuole which are encountered in otherwise typical polioencephalopathic models but in much lower number. Some axons underwent Wallerian degeneration, others met criteria of dystrophic neurites and both alteration existed in the same areas. In neurons, nuclear paracrystalline rod-like inclusions were visible; other inclusions comprised spiroplasma-like inclusions in synaptic boutons. Robust cellular reaction comprised of reactive astrocytes and macrophages filled with cellular debris.

Adult↗
PubMed1993

DNA methylation in folate deficiency: use of CpG methylase.

Folate deficiency produces a marked decrease in the ratio of S-adenosylmethionine to S-adenosylhomocysteine. This ratio regulates the activity of many cellular methylation reactions including that of DNA. We used bacterial CpG methylase to evaluate the effect of folate deficiency on methylation of DNA from livers of weanling rats fed an amino acid-defined folate deficient diet. After 4 weeks, liver DNA from deficient animals was undermethylated compared with DNA from pair-fed control animals.

Animals↗
PubMed1993

Spiralins.

Explore the source record for details and available documents.

Amino Acid Sequence↗
PubMed2005

A high sensitivity amperometric biosensor using laccase as biorecognition element.

An amperometric flow biosensor, using laccase from Rigidoporus lignosus as bioelement was developed. The laccase was kinetically characterized towards various phenolics both in solution and immobilized to a hydrophilic matrix by carbodiimide chemistry. A bioreactor connected to an amperometric flow cell by a FIA system was filled with the immobilized enzyme and the operational conditions of this biosensor were optimized as regards pH. Under the adopted experimental conditions, the immobilized enzyme oxidizes all the substrate molecules avoiding the need of cumbersome calibration procedures. The biosensor sensitivity, which was found to be 100 nA/microM for some of the tested substrates, resulted to be constant for more than 100 working days. This biosensor permits the detection of phenolics in aqueous solutions at concentrations in the nanomolar range and was successfully used to detect phenolics in wastewaters from olive oil mill without sample preparation.

Biosensing Techniques↗
PubMed2006

Implementation and performance evaluation of reconstruction algorithms on graphics processors.

The high-throughput needs in electron tomography and in single particle analysis have driven the parallel implementation of several reconstruction algorithms and software packages on computing clusters. Here, we report on the implementation of popular reconstruction algorithms as weighted backprojection, simultaneous iterative reconstruction technique (SIRT) and simultaneous algebraic reconstruction technique (SART) on common graphics processors (GPUs). The speed gain achieved on the GPUs is in the order of sixty (60x) to eighty (80x) times, compared to the performance of a single central processing unit (CPU), which is comparable to the acceleration achieved on a medium-range computing cluster. This acceleration of the reconstruction is caused by the highly specialized architecture of the GPU. Further, we show that the quality of the reconstruction on the GPU is comparable to the CPU. We present detailed flow-chart diagrams of the implementation. The reconstruction software does not require special hardware apart from the commercially available graphics cards and could be easily integrated in software packages like SPIDER, XMIPP, TOM-Package and others.

Algorithms↗
PubMedDate not supplied

Production of biodiesel by lipase-catalyzed transesterification of vegetable oils: a kinetics study.

Kinetics of production of biodiesel by enzymatic methanolysis of vegetable oils using lipase has been investigated. A mathematical model taking into account the mechanism of the methanolysis reaction starting from the vegetable oil as substrate, rather than the free fatty acids, has been developed. The kinetic parameters were estimated by fitting the experimental data of the enzymatic reaction of sunflower oil by two types of lipases, namely, Rhizomucor miehei lipase (RM) immobilized on ion-exchange resins and Thermomyces lanuginosa lipase (TL) immobilized on silica gel. There was a good agreement between the experimental results of the initial rate of reaction and those predicted by the proposed model equations, for both enzymes. From the proposed model equations, the regions where the effect of alcohol inhibition fades, at different substrate concentrations, were identified. The proposed model equation can be used to predict the rate of methanolysis of vegetable oils in a batch or a continuous reactor and to determine the optimal conditions for biodiesel production.

Algorithms↗
PubMed2004

Transesterification activity of lipases immobilized in a phyllosilicate sol-gel matrix.

Lipases from Pseudomonas cepacia (P.c.) and Thermomyces lanuginosa (T.l.) were immobilized in a phyllosilicate sol-gel matrix and studied for their ability to catalyze the alcoholysis of fats and oils to simple alkyl esters. At 50 degrees C and 48 h reaction immobilized T.l. lipase gave higher alkyl ester yields (70 to 100%) from fats and oils regardless of chain length or degree of unsaturation of the acyl groups in the triacylglycerols than did immobilized P.c. lipase (20-90%), which preferred unsaturated oils. Both immobilized lipases catalyzed ester formation (80-90%) from greases containing a range of free fatty acids (2.6 to 36%). Molecular sieves had no effect on ester yields in the immobilized T.l. lipase-catalyzed alcoholysis of greases but did improve yields (5-10%) in the immobilized P.c. lipase-catalyzed reactions.

Burkholderia cepacia↗
PubMed2004

Production of an anti-complement exo-polymer produced by Auricularia auricula-judae in submerged culture.

Exo-polymer (EP) was produced at 1.2 g l(-1) in submerged culture of Auricular auricula-judae. Crude EP (AJ-0) has 70% anti-complementary activity (inhibition of total complementary hemolysis 50%; ITCH50). The activating pathway of the complement system occurred through both the classical and alternative pathways, though the major pathway was the classical one. Fractionation of AJ-0 using Sepharose CL-6B gel chromatography gave three major fractions (AJ-Fr-I, II and III) of which the first was the most active. The mycelial growth and EP production of A. auricula-judae were optimal at pH 6, 25 degrees C and pH 5, 25 degrees C, respectively.

Biopolymers↗
PubMed2004

Cloning, characterization and expression of the polypeptide release factor gene, eRF1, of Blepharisma japonicum.

The polypeptide release factor gene, eRF1, of Blepharisma japonicum (Bj-eRF1) was cloned and sequenced. Its coding region was 1314 base pairs and encodes a protein of 437 amino acids. The cloned gene was expressed in Escherichia coli and the recombinant Bj-eRF1 polypeptide was purified by Ni2+-nitrilotriacetic acid agarose and Superose12 chromatography. Pull-down analysis showed that the recombinant Bj-eRF1 interacts with the heterologously-expressed release factor, eRF3C, of Euplotes octocarinatus.

Amino Acid Sequence↗
PubMed2000

Isolation of dermatoxin from frog skin, an antibacterial peptide encoded by a novel member of the dermaseptin genes family.

A 32-residue peptide, named dermatoxin, has been extracted from the skin of a single specimen of the tree frog Phyllomedusa bicolor, and purified to homogeneity using a four-step protocol. Mass spectral analysis and sequencing of the purified peptide, as well as chemical synthesis and cDNA analysis were consistent with the structure: SLGSFLKGVGTTLASVGKVVSDQF GKLLQAGQ. This peptide proved to be bactericidal towards mollicutes (wall-less eubacteria) and Gram-positive eubacteria, and also, though to a lesser extent, towards Gram-negative eubacteria. Measurement of the bacterial membrane potential revealed that the plasma membrane is the primary target of dermatoxin. Observation of bacterial cells using reflected light fluorescence microscopy after DNA-staining was consistent with a mechanism of cell killing based upon the alteration of membrane permeability rather than membrane solubilization, very likely by forming ion-conducting channels through the plasma membrane. CD spectroscopy and secondary structure predictions indicated that dermatoxin assumes an amphipathic alpha-helical conformation in low polarity media which mimic the lipophilicity of the membrane of target microorganisms. PCR analysis coupled with cDNA cloning and sequencing revealed that dermatoxin is expressed in the skin, the intestine and the brain. Preprodermatoxin from the brain and the intestine have the same sequence as the skin preproform except for two amino-acid substitutions in the preproregion of the brain precursor. The dermatoxin precursor displayed the characteristic features of preprodermaseptins, a family of peptide precursors found in the skin of Phyllomedusa ssp. Precursors of this family have a common N-terminal preproregion followed by markedly different C-terminal domains that give rise to 19-34-residue peptide antibiotics named dermaseptins B and phylloxin, and to the D-amino-acid-containing opioid heptapeptides dermorphins and deltorphins. Because the structures and cidal mechanisms of dermatoxin, dermaseptins B and phylloxin are very different, dermatoxin extends the repertoire of structurally and functionally diverse peptides derived from the rapidly evolving C-terminal domains of precursors of the dermaseptins family.

Alamethicin↗
PubMed2004

Homology modeling of the CG-specific DNA methyltransferase SssI and its complexes with DNA and AdoHcy.

Prokaryotic DNA methyltransferase M.SssI recognizes and methylates C5 position of the cytosine residue within the CG dinucleotides in DNA. It is an excellent model for studying the mechanism of interaction between CG-specific eukaryotic methyltransferases and DNA. We have built a structural model of M.SssI in complex with the substrate DNA and its analogues as well as the cofactor analogue S-adenosyl-L-homocysteine (AdoHcy) using the previously solved structures of M.HhaI and M.HaeIII as templates. The model was constructed according to the recently developed "FRankenstein's monster" approach. Based on the model, amino acid residues taking part in cofactor binding, target recognition and catalysis were predicted. We also modeled covalent modification of the DNA substrate and studied its influence on protein-DNA interactions.

2-Aminopurine↗
PubMedDate not supplied

Emmy Klieneberger-Nobel Award Lecture: The protein fingerprints of mycoplasmas.

The proteins of 91 strains of Mycoplasma from 19 established species and three groups of uncertain taxonomic position were separated by two-dimensional polyacrylamide gel electrophoresis. Considerable variations in protein patterns were found among strains from the same species or subspecies; the percentage of matching spots (% of congruence) ranged from 42%-100%, but many proteins were strongly conserved in all strains of a given species. Maps of these conserved proteins could be used to identify strains. It was concluded that (1) large colony-type strains of Mycoplasma mycoides subspecies mycoides are more closely related to M. mycoides subspecies capri than to small colony-type strains of M. mycoides subspecies mycoides; (2) Mycoplasma capricolum, Leach group 7, and the F38 group of mycoplasmas are all related to M. mycoides; (3) the 2D group of strains are not related to either M. mycoides or Mycoplasma bovis, (4) M. bovis and Mycoplasma agalactiae are closely related; (5) apart from a small overlap in pattern between Acholeplasma laidlawii and Acholeplasma granularum, the type strains of seven established species of Acholeplasma each had distinct protein patterns that justified their classification as separate species; and (6) analysis of two-dimensional protein patterns is a valuable method for resolving problems in mycoplasma taxonomy and for identifying strains.

Acholeplasma↗