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At least 775 records · Page 43Linked to original sources

PubMed1999

When did bovine spongiform encephalopathy (BSE) start? Implications on the prediction of a new variant of Creutzfeldt-Jakob disease (nvCJD) epidemic.

BACKGROUND: Knowing the starting date of the BSE epidemic and its size at the very beginning is crucial to interpret the timing of the nvCJD cases and to forecast the nvCJD epidemic. The first cases occurred in 1985. The models devised by Anderson (back-calculation) and Dealler (age-period-cohort) led to an estimate of less than 50 cases in 1983, and none earlier. Here, we applied age-cohort models to the BSE data in order to estimate the earliest possible date of the first unrecognized BSE cases. METHODS: The numbers of confirmed BSE cases in the UK, by age group and by calendar year from 1988 to 1996, were analysed by Poisson regression. The cases' age distribution was considered as constant between the different birth cohorts. The herd's age structure was taken into account. RESULTS: According to the models, BSE cases may have occurred as early as 1980. The expected number of cases before 1990 is almost twice the number of confirmed cases and exceeds by more than 20% the expected value of Anderson's model. The scenario of first human exposure in 1980 leads to fewer future nvCJD cases than predicted by Cousens with exposure patterns starting in 1983 or 1985. CONCLUSION: The first birth cohort available, consisting of two cases older than 10 in 1988, does not allow any projections before 1980. Moreover, confidence intervals are wide and the power of the study is limited by the great dispersion of the data; the precision of the estimations would be improved by considering geographical incidence. Nevertheless, our projections are consistent with Wilesmith's survey of rendering plants relating the emergence of BSE to the dramatic fall in the proportion of meat and bone meal following solvent extraction, initiated in the late 1970s (65% in 1977 to 10% in 1983).

Animals↗

PubMed2000

The Adam and Eve story as exemplar of an early-life variant of the oedipus complex.

The Adam and Eve story is construed as having an organizing function that facilitates the analytic understanding of certain patients. In this interpretation, the story epitomizes a psychodynamic in which progressive growth, with separation and individuation, of the young is experienced as perilous--not only to them, but also correspondingly to their procreators. In the myth, the increasing psychic and physical maturation of Adam and Eve produced a crisis. Not only was divine authority flouted, but also apprehensions were aroused that God might be humbled or diminished. This threatened him, evoking his wrath and leading to the punishment by abandonment of his youthful wards. It is suggested that the story depicts an emotional complex of widespread application and is an archaic version of the oedipus complex, continuous with the oedipus complex proper, but from an earlier stage of development. This archaic complex is delineated with clinical vignettes, and a clinical explication of its various components is provided. Clinical management is considered, particularly with reference to the challenge that a closed-system perspective (Fairbairn 1958) presents to a patient's development.

Adult↗

PubMed1987

Natural feline leukemia virus variant escapes neutralization by a monoclonal antibody via an amino acid change outside the antibody-binding epitope.

We have molecularly cloned a natural variant of feline leukemia virus subtype B. This isolate is unique in that it is not neutralized by a monoclonal antibody which neutralized all other feline leukemia virus isolates tested, including members of the A, B, and C subtypes. Western immunoblotting indicated that the monoclonal antibody was less able to bind to the gp70 of the resistant isolate (designated lambda B1) than to the gp70s of susceptible viruses. Nucleotide sequence analysis of the envelope gene of lambda B1 revealed a high degree of homology with the susceptible Snyder-Theilen, Gardner-Arnstein, and Rickard subtype B isolates, including the presence of a 5-amino-acid minimal binding epitope required for binding by the neutralizing monoclonal antibody. The only change within the vicinity of this epitope was in a single nucleotide, and this difference changed a proline residue to leucine three amino acids from the N terminus of the binding epitope. Competitive binding studies with synthetic peptides indicated that substitution of leucine for proline resulted in a 10-fold decrease in the ability of the peptide to compete for antibody binding to native antigen. The results are consistent with the interpretation that this amino acid change lowers the affinity of antibody binding, resulting in failure of the antibody to neutralize the variant virus.

Amino Acid Sequence↗

PubMed2026

STX1B variant-specific synaptic dysfunction is associated with network hyperexcitability in human iPSC-derived neurons.

BACKGROUND: Variants in STX1B/syntaxin-1B are linked to a spectrum of fever-associated epilepsy syndromes. While studies in murine models have provided mechanistic insights, their relevance to human disease in a heterozygous context may be limited. METHODS: We investigated two pathogenic STX1B variants using isolated single neurons and neuronal network cultures derived from patient-specific induced pluripotent stem cells. These carried either a de novo p.G226R variant, associated with severe developmental epilepsy, or an InDel variant (p.K45delinsRCMIE/p.L46M) linked to a transient familial seizure syndrome. Synaptic function and network excitability were assessed using patch-clamp and multi-electrode array recordings, alongside morphological and transcriptomic profiling. FINDINGS: G226R exhibited both gain- and loss-of-function characteristics, with increased miniature excitatory postsynaptic current frequency in networks but not in autapses, and synaptic failure during sustained high-frequency stimulation. For the InDel variant, the predicted loss-of-function phenotype based on reduced syntaxin-1B levels was not detectable at the single-cell level, likely masked by compensatory synaptic upregulation. At the network level, however, both variants were associated with neuronal hyperexcitability, characterised by more frequent and prolonged bursting activity, with a much stronger phenotype in G226R-containing networks. Transcriptomic profiling revealed a differential dysregulation of synaptic and other neuronal genes. INTERPRETATION: The divergence between morphological, electrophysiological and transcriptomic findings suggests that compensatory mechanisms may contribute to network hyperexcitability. Initially engaged to maintain homoeostasis, they may ultimately contribute to a pathological network state. The graded severity of network alterations across STX1B variants correlates with the clinical phenotypes. FUNDING: BMBF (Treat ION-01GM2210A, SNAREopathies-01EW1809A), 2023 FEBS Summer Fellowship, Fortüne programme (2610-0-0), EKFS college precise.net, Open Access Publishing Fund of University of Tübingen.

Humans↗

PubMed1994

Analysis of glycosylphosphatidylinositol membrane anchors by electrospray ionization-mass spectrometry and collision induced dissociation.

The multi-component nature of glycosylphosphatidylinositol membrane anchors makes the analysis of their structure complex. Nuclear magnetic resonance spectroscopy of delipidated glycosylphosphatidylinositol-peptide fractions can supply considerable information but requires relatively large quantities of material. High-sensitivity sequencing techniques are available for the oligosaccharide portions of glycosylphosphatidylinositol anchors, but there is no simple and generally applicable technique to complement this information. In this paper we describe the application of electrospray ionization-mass spectrometry and collision induced dissociation to study intact glycosylphosphatidylinositol-peptides from a Trypanosoma brucei variant surface glycoprotein. Collision of the [M + 4H]4+ pseudomolecular ions of two glycosylphosphatidylinositol-peptide glycoforms produced easily interpretable daughter ion spectra, from which detailed information on the lipid moiety, carbohydrate sequence and site of peptide attachment could be obtained. All of the collision induced dissociation cleavage events occurred in the glycosylphosphatidylinositol portion of the glycosylphosphatidylinositol-peptide. This technique supplies complementary data to the high-sensitivity oligosaccharide sequencing procedures and should greatly assist glycosylphosphatidylinositol anchor structure-function studies, particularly when sample quantities are limiting.

Amino Acid Sequence↗

PubMedDate not supplied

Characterization of a 14 kDa plant-related serine protease inhibitor and regulation of cytotoxic activity in earthworm coelomic fluid.

We have purified and characterized the serine protease inhibitor activity contained in the coelomic fluid of the earthworms, Eisenia. Serine protease inhibitor activity was stable between pH3 and 9.5, not flocculable by pH 3.0 and resistant to 100 degrees C for 15 min. or to 4 degrees C for 24 h. Ten microL of coelomic fluid was sufficient to inhibit in vitro the protease activity of 0.12 microgram of trypsin. Injection of living bacteria into earthworms resulted in increased serine protease activity 1-2 days post-injection, and increased serine protease inhibitor activity on day 4, suggesting that serine protease inhibitor is responsible for serine protease neutralization. Purified to homogeneity by affinity chromatography on trypsin, the serine protease inhibitor of Eisenia is a monomer of 14 kDa. Its partial NH2 amino acid sequence revealed a basic hydrophobic fragment which shared 68-75% homologies and 47-60% identities with several plant serine protease inhibitors. Eisenia cytotoxic activity due to the two fetidins of 40 and 45 kDa was stimulable in vitro by several serine proteases. Incubation with soybean trypsin inhibitor variant a (STIa) resulted in less cytotoxicity. The inhibitory effect occurred only when STIa was added before cell disruption. Interpretative cytotoxic scheme involving the release of intracellular cytotoxic proteins, intracellular trypsin-like activator and extracellular serine protease inhibitor suggests regulatory mechanisms for cellular/humoral immune system of earthworms.

Aeromonas hydrophila↗

PubMed2002

Analysis of the relationship between mannose-binding lectin (MBL) genotype, MBL levels and function in an Australian blood donor population.

The mannose-binding lectin (MBL) pathway of complement activation is an important component of innate host defence. Numerous studies have described associations between the MBL genotype, MBL levels and disease susceptibility. However, genotyping and quantitative assays used in these studies have frequently been limited, and comprehensive data examining the interaction between structural and coding MBL genetic variants, MBL antigenic levels and MBL functional activity are lacking. Such data may be important for accurate planning and interpretation of studies of MBL and disease. This study has examined MBL in a cohort of 236 Australian blood donors. Five MBL promoter and coding single nucleotide polymorphisms were genotyped using polymerase chain reaction-sequence-specific priming (PCR-SSP). Plasma levels of MBL antigen were quantified using a double-antibody enzyme-linked immunosorbent assay (ELISA), and functional MBL levels were quantified using a mannan-binding assay. Activation of the complement pathway by MBL was measured in a C4-deposition assay. Significant associations were found between both coding and promoter polymorphisms and MBL antigenic and functional levels. There was significant correlation between the results of MBL double-antibody, mannan-binding and C4-deposition assays. Comprehensive MBL genotyping and functional MBL quantitation using mannan-binding and C4-deposition assays have the potential to be highly informative in MBL disease association studies.

Australia↗

PubMed2003

The YggX protein of Salmonella enterica is involved in Fe(II) trafficking and minimizes the DNA damage caused by hydroxyl radicals: residue CYS-7 is essential for YggX function.

Previous work from our laboratory identified YggX as a protein whose accumulation increased the resistance of Salmonella enterica to superoxide stress, reversed defects attributed to oxidized [Fe-S] clusters, and decreased the spontaneous mutation frequency of the cells. Here we present work aimed at determining why the accumulation of YggX correlates with reduced mutation frequency. Genetic and biochemical data showed that accumulation of YggX reduced the damage to DNA by hydroxyl radicals. The ability of purified YggX to protect DNA from Fenton chemistry mediated damage in vitro and to decrease the concentration of Fe(II) ions in solution available for chelation provided a framework for the interpretation of data obtained from in vivo experiments. The interpretation of in vitro assay results, within the context of the in vivo phenotypes, was validated by a mutant variant of YggX (C7S) that was unable to function in vivo or in vitro. We propose a model, based on data presented here and reported earlier, that suggests YggX is a player in Fe(II) trafficking in bacteria.

Bacterial Proteins↗

PubMed1981

The role of human genetic monitoring in the workplace.

The history and current state of some newer short-term tests for occupational genetic monitoring are reviewed. These are: cytogenetics, sister chromatid exchange, body fluid analysis, tests utilizing sperm, and detection of somatic cell variants. Occupational studies on benzene, vinyl chloride monomer, and epichlorohydrin are critically discussed from the standpoints of design and interpretation. It is concluded that these tests are not appropriate for risk assessment at the present time. Their clinical relevance, if any, is unknown. Proper validation and standardization have not been done, and design problems have often clouded the results of previous studies. There is a critical need for further research in the area of occupational genetic monitoring. Future applications should include integration with prospective morbidity and mortality studies, standardization of design and statistical methods, and development of new tests with genetically relevant endpoints.

Benzene↗

PubMed2001

Driven to distraction: dual-Task studies of simulated driving and conversing on a cellular telephone.

Dual-task studies assessed the effects of cellular-phone conversations on performance of a simulated driving task. Performance was not disrupted by listening to radio broadcasts or listening to a book on tape. Nor was it disrupted by a continuous shadowing task using a handheld phone, ruling out, in this case, dual-task interpretations associated with holding the phone, listening, or speaking, However significant interference was observed in a word-generation variant of the shadowing task, and this deficit increased with the difficulty of driving. Moreover unconstrained conversations using either a handheld or a hands-free cell phone resulted in a twofold increase in the failure to detect simulated traffic signals and slower reactions to those signals that were detected. We suggest that cellular-phone use disrupts performance by diverting attention to an engaging cognitive context other than the one immediately associated with driving.

Adolescent↗

PubMed2006

Balancing selection and its effects on sequences in nearby genome regions.

Our understanding of balancing selection is currently becoming greatly clarified by new sequence data being gathered from genes in which polymorphisms are known to be maintained by selection. The data can be interpreted in conjunction with results from population genetics models that include recombination between selected sites and nearby neutral marker variants. This understanding is making possible tests for balancing selection using molecular evolutionary approaches. Such tests do not necessarily require knowledge of the functional types of the different alleles at a locus, but such information, as well as information about the geographic distribution of alleles and markers near the genes, can potentially help towards understanding what form of balancing selection is acting, and how long alleles have been maintained.

Animals↗

PubMed1997

PCR mutagenesis-based method for generation of positive controls for SSCP analysis.

We have developed a primer-mediated PCR mutagenesis-based method for the generation of positive controls to test the sensitivity of single-strand conformation polymorphism (SSCP) or any other PCR-based mutation screening method. This technique is based on the incorporation of a third longer primer, containing a mismatched base, into the PCR along with the two wild-type primers normally used to amplify DNA fragments for SSCP analysis. The longer mismatch primer (LMP) shares the sequence of one of the wild-type primers and also contains 5 to 10 additional bases, which include the mismatched base. The resulting PCR product is identical in length and sequence to the wild-type template with the exception that the LMP base mismatch is incorporated into nearly 100% of the product. We have observed an altered SSCP mobility pattern in all cases where positive controls have been generated using this technique. We believe that the use of such in vitro-generated controls can contribute to the interpretation of band patterns and to the optimization of experimental conditions for SSCP to facilitate maximum detection of sequence variants.

Base Sequence↗

PubMed2005

Unilateral or asymmetric localization of lambda waves is not a pathologic finding.

This article reports on three children who underwent an electroencephalographic examination. All three showed the feature of asymmetric lambda waves, which is usually interpreted as a pathologic focal phenomenon. The report documents that asymmetric lambda waves and photic driving might be normal variants, not requiring further investigation.

Brain↗

PubMed1987

Strong association between the major histocompatibility complex and systemic lupus erythematosus in southern Chinese.

The distribution of HLA-A, B, and DR alleles has been studied in 100 Chinese patients with systemic lupus erythematosus and in 100 healthy Chinese controls. Complement components factor B, C4A and C4B were studied in 72 patients and 61 controls. There was no significant difference between patients and controls in the distribution of HLA-A, HLA-B, factor B and C4B alleles, but there was a significant excess of HLA-DR2 and C4A null in the patients. An unusual variant of C4B was found in 6 patients and 1 control. The possible role of haplotypes is considered in interpreting these results and relating them to previous findings in Chinese.

Adolescent↗

PubMedDate not supplied

[Behavioral activity in an uncertain environment (the methodological characteristics of an experimental study)].

A fundamental resemblance between processes of probabilitive training and conditional reflex forming exist wile using lowintensive signal stimulus and probabilitive way of confirmation. A base of intrinsic unity of these methodical variants is a complicated way of elicitation of bond between signal stimulus and confirmation, absence of one-way interpreted information about an environment presuming probabilitive estimate using. In this case informative interaction between an individual and subjectively accidental environment takes place or the same, a process of subjectively probabilitive training. Accordingly probabilitive training is a dinamic process of training under conditions of subjective uncertainty based probabilitive estimate application and feedback elements existence.

Animals↗

PubMed1997

MRA of venous sinus thrombosis.

Intracranial venous magnetic resonance angiography (MRA) provides excellent visualization of dural venous sinuses and large deep and superficial cerebral veins noninvasively. It is a very useful imaging technique to evaluate venous sinus thrombosis. It also provides the planning and monitoring endovascular thrombolytic treatment for dural sinus thrombosis. Familiarization with normal intracranial venous anatomy and its normal variants as well as recognition of its pitfalls and artifacts of the venous MRA techniques are critical for making interpretation of venous sinus thrombosis correctly.

Humans↗

PubMedDate not supplied

A comprehensive review of genetic association studies.

Most common diseases are complex genetic traits, with multiple genetic and environmental components contributing to susceptibility. It has been proposed that common genetic variants, including single nucleotide polymorphisms (SNPs), influence susceptibility to common disease. This proposal has begun to be tested in numerous studies of association between genetic variation at these common DNA polymorphisms and variation in disease susceptibility. We have performed an extensive review of such association studies. We find that over 600 positive associations between common gene variants and disease have been reported; these associations, if correct, would have tremendous importance for the prevention, prediction, and treatment of most common diseases. However, most reported associations are not robust: of the 166 putative associations which have been studied three or more times, only 6 have been consistently replicated. Interestingly, of the remaining 160 associations, well over half were observed again one or more times. We discuss the possible reasons for this irreproducibility and suggest guidelines for performing and interpreting genetic association studies. In particular, we emphasize the need for caution in drawing conclusions from a single report of an association between a genetic variant and disease susceptibility.

Alleles↗

PubMed2006

Iterative image reconstruction using prior knowledge.

A method is proposed to reconstruct signals from incomplete data. The method, which can be interpreted both as a discrete implementation of the so-called prior discrete Fourier transform (PDFT) spectral estimation technique and as a variant of the algebraic reconstruction technique, allows one to incorporate prior information about the reconstructed signal to improve the resolution of the signal estimated. The context of diffraction tomography and image reconstruction from samples of the far-field scattering amplitude are used to explore the performance of the method. On the basis of numerical computations, the optimum choice of parameters is determined empirically by comparing image reconstructions of the noniterative PDFT algorithm and the proposed iterative scheme.

Algorithms↗