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At least 1,279 records · Page 71Linked to original sources
PubMed2000

Molecular breeding of allergy vaccines and antiallergic cytokines.

Molecular breeding, also called DNA shuffling, is a technology that enables the generation of large libraries of novel genes and vectors, from which improved variants can be selected based on functional properties. In a common format, it involves recursive recombination and mutation, performed by random fragmentation of related DNA sequences, followed by reassembly of the fragments in a self-priming polymerase chain reaction. As in natural evolution, the technique takes advantage of crossovers, deletions, insertions, inversions and point mutations of genes to generate large pools of related sequences. Molecular breeding can be used to generate improved variants of proteins used as therapeutics, such as vaccine antigens, growth factors and immunomodulatory molecules. Moreover, the technology can be applied to evolve entire viruses or vectors, including DNA vaccines. Cytokines downregulating allergic immune responses and allergens are attractive targets for evolution by molecular breeding. This review describes approaches to generate chimeric allergens with T cell epitopes from multiple allergen homologues, while reducing the recognition by preexisting IgE. In addition, the results and applications of molecular breeding in the evolution of improved antiallergic cytokines are discussed.

Allergens↗
PubMed2000

[Angiocentric T-cell lymphoma]

SUMMARY: The CD20+ variant of angiocentric T-cell lymphoma is an unusual type of T-cell lymphomas that present cystic changes in organs because of ischaemic necroses. The purpose of this study was to describe a case of CD20+angiocentric T-cell lymphoma, discussing its clinical, histopathological and immunohistochemical features, to analyze its proliferation kinetics and to consider its possible relationship to the Epstein-Barr virus (EBV) to understand better the pathobiological nature of the disease. METHODS: The clinical, histopathological, immunohistochemical and single-cell DNA cytophotometric features of the case were analyzed. In addition in situ hybridization was performed to detect EBV. RESULTS: The 24 years old woman was admitted to our Institute because of pain in the abdominal region and weight loss. There were enlarged lymph nodes on the neck, and biopsy was done. Histological diagnosis: angiocentric T-cell lymphoma, CD20+ variant. CD3, CD43, CD45RA and CD45R0 antigens were positive in the atypic lymphoid cells of the tumour and in cells infiltrating the vascular wall. DNA index was 0.8589 (hypodiploid). Tumour cells in G1 phase: 47%, S phase: 45.4%, G2 phase: 7.6%. Combined chemotherapy was administered because of clinical stadium IV/B of malignant lymphoma (5 CHOP-Bleo, CEPP, CEP, CMVE treatment). The disease showed gradual progression and the patient died 14 months after the first symptoms had appeared. CONCLUSIONS: In the last 13 years there were 5 cases of angiocentric T-cell lymphoma at our Institute. The CD20+ variant is rare, its clinical symptoms are special, the prognosis is unfavourable. The cause why we demonstrate this case is to call attention to a new treatment for these patients by immunotherapy using monoclonal antibodies against CD20 antigen.

Journal Article↗
PubMed1987

[The necessity for intragroup individualization of diet No. 5 in hepatobiliary diseases].

The frequency of cholelithiasis in Bulgaria has increased 9 times for the last 15 years. At the same time 40.5% of the patients with cholelithiasis are obese--II-IV degree of obesity. This fact calls for individualization of diet No 5 which in this country is applied to patients with liver and biliary diseases. A variant diet No 5-x for patients with cholelithiasis and abnormal body mass is proposed. This diet keeps the protein and fat components of diet No 5 but reduces the carbohydrates quantity from 346 g to 195-200 g which leads to the reduction of the daily intake of calories from 2369-2450 to 1700. The individualization of diet No 5 and the introduction of diet No 5-x in patients with biliary diseases will ensure a greater prophylactic and therapeutic efficacy of the dietetic treatment of patients with cholelithiasis and other biliary diseases combined with various degree of obesity.

Bile Duct Diseases↗
PubMed1996

[The controversy about so-called "active euthanasia"].

In the past few years, the discussion about the right to kill severely ill patients for humanitarian reasons--once called euthanasia and after World War II in the German speaking countries as euphemism called 'aktive Sterbehilfe' (active help to die)--has become more intensive. Actually, only the Netherlands do officially practice euthanasia. But the variant that consists in putting a pharmaceutical at the patient's disposal in order to kill himself is very well known in other countries, e.g. in Switzerland, where the pressure on the legislator to also legalize euthanasia grows. Taking into account medico-ethical reasons, historical experiences, alarming euthanasia ideas in bioethics and social philosophy, the danger due to the impossibility to control the development in this field, and the insidious extension of euthanasia indications, the author rejects firmly the idea of legalized euthanasia. These problems are related to those that occur in fixing the moment of death of potential organ donors. A lack of organs in transplantation medicine should not lead physicians to explant organs from donors in a dying condition. For physicians who take care of potential organ donors and who have to look after their interests towards transplantation teams, it is often too difficult to cope with this task. Local ethical commissions should support them.

Brain Death↗
PubMed1996

Molecular variants of fibronectin and laminin: structure, physiological occurrence and histopathological aspects.

This review deals with biological and pathological aspects of various isoforms of the matrix molecules fibronectin and laminin. They are generated by different molecular mechanisms: ED-A+ and ED-B+ fibronectin by alternative splicing of pre mRNA, de novo-glycosylated fibronectin by alternative post-translational O-linked glycosylation of the IIICS region, and the laminin isoforms by exchange of single chains of the heterotrimeric molecule. In contrast to the "common" fibronectin, the distribution of ED-B+ and de novo-glycosylated fibronectin is restricted to embryonic tissues; they subsequently reappear in granulation tissue, in fibrosing processes and in tumour stroma. The expression of these so-called oncofetal fibronectins is stimulated by growth factors (TGF beta). The association of the ED-B+ fibronectin with proliferative activity and newly formed vessels identifies this fibronectin variant as a marker of cellular activity in the process of fibrosis and as a suitable agent for the evaluation of tumour angioneogenesis. Initial results suggest a correlation between the amount of ED-B+ and de novo-glycosylated fibronectin in tumour stroma and the behaviour of carcinomas with regard to their invasiveness and propensity for metastatic dissemination. The current nomenclature of the laminin molecule family is presented. The laminin chain constitution of basement membranes switches from embryonic or proliferatively active to adult terminally differentiated tissues [disappearance of the laminin beta 2 (s) chain] and depends on the tissue type. The discrepancy between the loss of basement membranes (multiple basement membrane defects) in carcinomas and the recently reported increased laminin chain synthesis in these tumours may be explained by abundant laminin chain deposition outside the basement membrane in the carcinoma invasion front, possibly associated with enhanced adhesion of budding tumour cells.

Animals↗
PubMed2005

Bilateral paramedian midbrain infarct: an uncommon variant of the "top of the basilar" syndrome.

Occlusion of the rostral portion of the basilar artery can result in ischaemia of the midbrain and thalami, as well as of the temporal and occipital lobes. The so called "top of the basilar" syndrome manifests clinically as numerous combinations of abnormalities of alertness, sleep-wake cycle, and behaviour and oculomotor or pupillomotor functions. A 67 year old man presented with bilateral internuclear ophthalmoplegia, rubral tremor, and daytime somnolence. He was awake during the night and mostly agitated and aggressive. An ischaemic lesion was visible on the magnetic resonance (MR) image in the central portion of the midbrain just ventral to the aqueduct, clearly affecting the paramedian structures bilaterally. MR angiographic images demonstrated a hypoplastic basilar artery ending in both superior cerebellar arteries. Both posterior cerebral arteries were seen to arise from the corresponding internal carotid arteries via the posterior communicating branches. This unique case of an acute bilateral paramedian infarct represents a highly uncommon variant of the "top of the basilar" syndrome and was due to the affected ischaemic territory--that is, the "distal field" of the variant basilar artery.

Aged↗
PubMedDate not supplied

Nasal polyps update. Histopathology.

Sinonasal polyps are benign mucosal swellings that occur in four different histological patterns. The most common type is the edematous, eosinophilic (so-called "allergic") nasal polyp, which constitutes 85-90% of nasal polyps. The edematous polyp is morphologically characterized by edema, goblet cell hyperplasia of the epithelium, thickening of the basement membrane, and of numerous leukocytes, predominantly eosinophils. The second histological type is a fibroinflammatory polyp characterized by chronic inflammation and metaplastic changes of the overlying epithelium. Another rare variant presents with pronounced hyperplasia of seromucinous glands, but otherwise shows many similarities with the edematous type of polyp. The fourth type is very rare and is a polyp with atypical stroma. This latter polyp calls for awareness and careful histological examination to avoid misdiagnosis of a neoplasm.

Humans↗
PubMed1978

[On the occurrence of so-called clear cells in salivary gland tumors. Ultrastructure and differential diagnosis (author's transl)].

Clear cell tumors of the salivary glands are monomorphic clear cell adenomas, clear cell carcinomas, clear cell variants of acinic cell and mucoepidermoid tumours, sebaceous cell tumors, salivary duct carcinomas and pleomorphic adenomas with clear cell sectors. At the light microscopical level the descriptive term of the clear cell comprises cell types of different origin and functional importance which can be differentiated by cytochemistry and electron microscopy. The following cell types were analysed precisely: indifferent duct cells (small formation of organelles, desmosomes), storing striated duct cells (glycogen granules, multiple mitochondrias, basal labyrinth), myoepithelial cells (myofilaments, pinocytosis vesicles, lipofuscin granules, hemidesmosomes), goblet cells (mucous vacuoles, basal endoplasmatic reticulum), sebaceous cells (lipid droplets, microvilli, desmosomes) and clear acinic cells (electron pale secretory granules, small mitochondrias, small golgi apparatus). Clear cell tumor types of the salivary gland region which primarely do not derive from the salivary gland tissue must also be included in the differential diagnoses. These are metastases of hypernephroid renal carcinomas, paragangliomas, glomus tumors of Masson, granular cell tumor and alveolar soft-part sarcomas.

Adenoma↗
PubMed1998

Expression and characterization of a dopamine D4R variant associated with delusional disorder.

Multiple genetic polymorphisms of the human dopamine D4 receptor (hD4R) have been identified including a 12 bp repeat in exon 1 associated with a psychotic condition called delusional disorder. Competition binding assays revealed minor pharmacological differences between the recombinant A1 (normal) and A2 (delusional) proteins with respect to quinpirole and the antipsychotic clozapine, however no functional differences were detected for receptor activation by dopamine, epinephrine, or norepinephrine. Our results suggest that this polymorphism may only confer susceptibility to delusional disorder in combination with other genetic or environmental factors.

Animals↗
PubMed2026

High-accuracy SNV calling for bacterial isolates using deep learning with AccuSNV.

Accurate detection of mutations within bacterial species is critical for fundamental studies of microbial evolution, reconstruction of transmission events, and identification of antimicrobial resistance mutations. Although many tools have been developed to identify single-nucleotide variants (SNVs) from whole-genome sequencing, they often suffer from high false-positive rates owing to the complexity of bacterial genomes and the need for different filtering cutoffs across sample types and sequencing depths. As data sets increase in size, the manual filtering required for high accuracy presents a significant obstacle. Here, we present AccuSNV, a novel deep learning-based tool for high-precision and automated bacterial SNV calling. Unlike traditional methods that process one sample at a time, AccuSNV leverages a convolutional neural network (CNN) that integrates alignment information across multiple samples, enhancing precision through learned across-sample patterns. We evaluate AccuSNV against seven popular SNV-calling tools using simulated data from six bacterial species with varied sequencing depths, numbers of isolates, mutations, and divergence levels. To further validate its real-world utility, we test AccuSNV on multiple curated bacterial data sets containing reported SNVs. In both simulated and real-world scenarios, AccuSNV consistently achieves the best performance. Moreover, AccuSNV provides comprehensive user-friendly downstream analysis modules and outputs, including mutation annotation information, phylogenetic inference, d N/d S calculations, and optional manual filtering. Together with the automated deep learning-based calling, these features make AccuSNV broadly accessible to users with different levels of computational expertise.

Deep Learning↗
PubMed1992

Recombinant chicken egg white cystatin variants of the QLVSG region.

Using recombinant DNA methods, seven cystatin variants were produced by cassette mutagenesis of a chicken egg white cystatin variant which already contains the mutations Ala3, Glu2, Phe1, Ser1-->Met, Met29-->and Met 89-->Leu. When characterized by structural and functional studies, they were all found to harbour mutations in the first hairpin loop, the so-called 'QXVXG' region, which is highly conserved within the cystatin superfamily and thought to be important for its inhibitory activity towards cysteine proteinases. They were purified to more than 90% homogeneity and analysed by SDS/PAGE, HPLC, tryptic peptide mapping, N-terminal amino acid sequencing and ELISA. Structural model building of the variants and their complexes with papain was performed using computer graphics based on the crystallographic coordinates of chicken egg white cystatin and the papain-stefin complex. Only minor conformational changes were required for modelling the mutants or complexes. Equilibrium dissociation constants and rate constants of complex formation of the variants with papain, actinidin as well as cathepsin B and L were determined by kinetic measurements using fluorogenic substrates. The single exchanges Gln53-->Glu, Gln53-->Asn, Val44-->Asp, Gly57-->Ala and the double exchanges Arg52-->Leu, Gln53-->Glu, Gln53-->Asn, Ser56-->Ala, Leu54-->Met, Gly57-->Ala reduced the inhibition of papain, actinidin and cathespin B significantly by 10-1000-fold. With the exception of the Val55-->Asp variant, the differences in the Ki values are mainly due to larger k off values, whereas the kon values seem to be more or less unaffected by the selected mutations. The effect on the inhibition of papain is generally smaller than the effects on actinidin and cathepsin B inhibition. Cathepsin L inhibition is strikingly insensitive to all mutations. These distinct effects of the inhibitor variants indicate differences in proteinase-inhibitor-protein interactions between closely related cysteine proteinases. In addition, the results verify the prediction, made earlier from sequence alignment studies and from a docking model of the chicken cystatin-papain complex, that the first hairpin loop of cystatins is essential for effective inhibition.

Amino Acid Sequence↗
PubMed1992

An explanation for the defect in secretion of IgM Mott cells and their predominant occurrence in the Ly-1 B cell compartment.

Mott cells are a variant form of plasma cell in which the immunoglobulin (Ig), rather than being secreted, accumulates in rough endoplasmic reticulum-derived vesicles called Russell bodies. We have examined the molecular cause of this defect and the in vivo origin of IgM Mott cells. Our examination of the Ig variable region gene sequences of two IgM Mott hybridomas derived from C.B-20 Ly-1 B cells showed all to be germ line. In a series of mix and match transfection experiments, the Mott phenotype was only reconstituted when the original Mott specificity was expressed as an IgM, suggesting that both the specificity and the isotype were critical to the formation of Russell bodies. Based on our finding that Russell body formation was dependent on the Ig isotype being IgM, we suggest that the Mott phenotype is apparent only after differentiation of B cells into plasma cells and that probably the major cause of the IgM Mott phenotype is low-affinity interaction of the Mott Ig with some as yet unknown intracellular component(s) being stabilized by the intrinsic high avidity of the pentameric secreted form of IgM. Consistent with this proposal was the finding that after in vitro lipopolysaccharide (LPS) stimulation of sorted Ly-1 B cells derived from C.B-20 mice, Mott cells represented up to 5% of the IgM plasma cells in the culture. LPS stimulation of conventional B cells also induced the appearance of IgM Mott cells, but at the much reduced level of 0.1%, suggesting that the major, if not the only, source of Mott cells in vivo is the Ly-1 B cell population. A possible causal relationship between the elevated frequency of Mott cells in the Ly-1 B cell-derived LPS blasts and the repertoire selection inherent in the development of these B cells is discussed.

Amino Acid Sequence↗
PubMed2005

Application of genomewide SNP arrays for detection of simulated susceptibility loci.

The prospect of SNP-based genomewide association analysis has been extensively discussed, but practical experiences remain limited. We performed an association study using a recently developed array of 11,555 SNPs distributed throughout the human genome. A total of 104 DNA samples were hybridized to these chips with an average call rate of 97% (range 85.3-98.6%). The resulting genomewide scans were applied to distinguish between carriers and noncarriers of 37 test variants, used as surrogates for monogenic disease traits. The test variants were not contained in the chip and had been determined by other methods. Without adjustment for multiple testing, the procedure detected 24% of the test variants, but the positive predictive value was low (2%). Adjustment for multiple testing eliminated most false-positive associations, but the share of true positive associations decreased to 10-12%. We also simulated fine-mapping of susceptibility loci by restricting testing to the immediate neighborhood of test variants (+/-5 Mb). This increased the proportion of correctly identified test variants to 22-27%. Simulation of a bigenic inheritance reduced the sensitivity to 1%. Similarly adverse effect had reduction of allelic penetrance. In summary, we demonstrate the feasibility and considerable specificity of SNP array-based association studies to detect variants underlying monogenic, highly penetrant traits. The outcome is affected by allelic frequencies of chip SNPs, by the ratio between simulated "cases" and "controls," and by the degree of linkage disequilibrium. A major improvement is expected from raising the density of the SNP array.

Alleles↗
PubMed1993

Cytokines and growth factors in the regulation of bone remodeling.

Osteoporosis and periodontal disease both represent examples of abnormal bone remodeling. As knowledge of the cellular and molecular events in the normal bone remodeling process has accumulated in the last decade, better understanding of the pathophysiology of bone loss associated with periodontal disease and with aging has occurred. This short review does not attempt to include all aspects of this topic but covers specific areas in which there have been recent advances. (1) Observations made in the last few years have indicated that a hierarchy of both receptor and nonreceptor tyrosine kinases may be involved in normal osteoclastic bone resorption and that certain members of these tyrosine kinase families may mediate cytokine effects. Studies in the op/op variant of murine osteopetrosis have shown that normal production of monocyte-macrophage colony-stimulating factor 1 (M-CSF, also called CSF-1) and activation of its receptor (the receptor tyrosine kinase c-fms) are required for normal osteoclast formation. (2) Studies in mice made deficient in nonreceptor tyrosine kinase by gene knockout have shown that expression of this nonreceptor tyrosine kinase is required for normal osteoclast action and ruffled border formation, although not for osteoclast formation. (3) Recent studies have shown that in addition to prostaglandins of the E series, other arachidonic acid metabolites may be involved in normal and abnormal osteoclastic bone resorption. 5-Lipoxygenase metabolites, the leukotrienes, stimulate isolated osteoclasts to form resorption pits as well as cause osteoclastic bone resorption in organ cultures of neonatal mouse calvariae. These compounds, which are unstable in tissue culture media, are readily inhibitable by agents that inhibit 5-lipoxygenase enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed2001

Varicella-zoster virus with a lost gE epitope: evidence for immunological pressure by the human antibody response.

The varicella-zoster virus (VZV) genome contains about 70 open reading frames (ORF). ORF 68 codes for glycoprotein gE, formerly called gpl, which is the predominant VZV glycoprotein; gE is a typical type 1 transmembrane protein with 623 amino acids. Recently, a variant virus was discovered which has a mutation in gE codon 150; this mutation converts an aspartic acid into an asparagine residue.

Adult↗
PubMed1988

Bacteriophage lambda DNA packaging: a mutant terminase that is independent of integration host factor.

Lambda+ is able to grow in Escherichia coli cells lacking integration host factor (IHF), producing a burst of approximately 25% that produced in IHF+ cells. In vitro, however, we find that the lambda DNA packaging enzyme terminase is strongly dependent on IHF in both cos cleavage reactions and DNA packaging reactions. The cos59 mutation renders lambda dependent on IHF in vivo. The cos59 mutation is a deletion of 3 base pairs at the XmnI site in the cohesive end site (cos) of lambda. Variants of lambda cos59 that were able to grow in the absence of IHF were isolated and found to carry a mutation, called ms1, in the Nu1 gene, which codes for the small subunit of terminase. The Nu1ms1 mutation results in a change of the 40th amino acid of the Nu1 gene product from leucine to phenylalanine. The Nu1ms1 terminase was independent of IHF in packaging reactions in vitro. The results indicate that the mutation either renders terminase: (1) able to utilize some host protein other than IHF, or (2) totally independent of host factors.

Bacterial Proteins↗
PubMed2005

Isoform-specific silencing of the Livin gene by RNA interference defines Livin beta as key mediator of apoptosis inhibition in HeLa cells.

Livin (alternatively called ML-IAP or KIAP) is a cancer-associated member of the antiapoptotic inhibitor of apoptosis protein family. Two splicing variants of Livin, designated Livin alpha and Livin beta, have been identified. The significance of these isoforms for Livin-mediated apoptosis inhibition is largely unclear. Using an isoform-specific RNA interference (RNAi) strategy, we silenced endogenous Livin expression in HeLa cells. We found that the targeted inhibition of Livin beta, but not of Livin alpha, blocked the growth of HeLa cells in clonogenic survival assays. In addition, silencing of Livin beta, but not of Livin alpha, sensitized HeLa cells to different proapoptotic stimuli such as UV irradiation, tumor necrosis factor alpha, or etoposide. These events were linked to activation of caspase-3 and increased poly(ADP-ribose) polymerase cleavage, specifically upon silencing of Livin beta. The proapoptotic sensitization of HeLa cells upon RNAi-mediated silencing of the endogenous livin gene was specifically reverted by ectopic expression of Livin beta but not of Livin alpha. We conclude that the Livin beta isoform plays the key role for the antiapoptotic protection of HeLa cells by the livin gene. Our results show that the Livin isoforms can strongly differ in their functional significance for the antiapoptotic resistance of tumor cells. Studies evaluating Livin as a novel diagnostic and prognostic tumor marker should benefit from isoform-specific expression analyses.

Adaptor Proteins, Signal Transducing↗
PubMed2025

Leveraging local ancestry and cross-ancestry genetic architecture to improve genetic prediction of complex traits in admixed populations.

The broader application of polygenic risk score (PRS) is hindered by the limited transferability of PRS developed in Europeans to non-European populations. While many statistical methods have been developed to improve the performance of PRS in non-European populations, most of them focused on discrete genetic ancestry clusters and did not consider admixed individuals. Admixed individuals pose a unique challenge for PRS calculation due to the complexity of local ancestry and cross-ancestry effect sizes. Here, we present a statistical method called SDPR_admix for calculating PRS in admixed individuals. SDPR_admix characterizes the joint distribution of the effect sizes of a genetic variant with two ancestries to be both zero, ancestry enriched, or shared with correlation. SDPR_admix outperformed other methods in simulations and improved the prediction of real traits in European-African admixed individuals in UK Biobank when trained on the Population Architecture using Genomics and Epidemiology (PAGE) dataset (N = 13,000). Deployment of SDPR_admix on All of Us (N = 52,000) further increased the prediction accuracy by approximately 5-fold on average compared with training on PAGE. This enhancement was achieved with manageable computational time and cost, demonstrating the feasibility of training PRS models on large-scale All of Us data. We provided several examples demonstrating that both ancestral-enriched and shared effects, as included in the SDPR_admix prediction model, are helpful for improving polygenic prediction in admixed populations. We also applied SDPR_admix to construct PRS for admixed Americans with mixture of European and Amerindigenous ancestries and showed that SDPR_admix overall outperformed other methods.

Humans↗