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J Decker

Publications and source records attributed to J Decker.

At least 37 records · Page 2Linked to original sources
PubMed1996

The heterosexual human immunodeficiency virus type 1 epidemic in Thailand is caused by an intersubtype (A/E) recombinant of African origin.

Since 1989, human immunodeficiency virus type 1 (HIV-1) has spread explosively through the heterosexual population in Thailand. This epidemic is caused primarily by viruses classified as "subtype E", which, on the basis of limited sequence comparisons, appear to represent hybrids of subtypes A (gag) and E (env). However, the true evolutionary origins of "subtype E" viruses are still obscure since no complete genomes have been analyzed, and only one full-length subtype A sequence has been available for phylogenetic comparison. In this study, we determined full-length proviral sequences for "subtype E" viruses from Thailand (93TH253) and the Central African Republic (90CR402) and for a subtype A virus from Uganda (92UG037). We also sequenced the long terminal repeat (LTR) regions from 16 virus strains representing clades A, C, E, F, and G. Detailed phylogenetic analyses of these sequences indicated that "subtype E" viruses do indeed represent A/E recombinants with multiple points of crossover along their genomes. The extracellular portion of env, parts of vif and vpr, as well as most of the LTR are of subtype E origin, whereas the remainder of the genome is of subtype A origin. The possibility that the discordant phylogenetic positions of "subtype E" viruses in gag- and env-derived trees are the result of unusual rates or patterns of evolution was also considered but was ruled out on the basis of two lines of evidence: (i) phylogenetic trees constructed for synonymous and nonsynonymous substitutions yielded the same discordant branching orders for "subtype E" gag and env gene sequences, thus excluding selection-driven evolution, and (ii) multiple crossovers in the viral genome are most consistent with the copy choice model of recombination and have been observed in other documented examples of HIV-1 intersubtype recombination. Thai and CAR "subtype E" viruses exhibited the same pattern of A/E mosaicism, indicating that the recombination event occurred in Africa prior to the spread of virus to Asia. Finally, all "subtype E" viruses were found to contain a distinctive two-nucleotide bulge in their transactivation response (TAR) elements. This feature was present only in viruses which also contained a subtype A 5' pol region (i.e., subtype A viruses or A/D and A/E recombinants), raising the possibility of a functional linkage between the TAR region and the polymerase. The implications of epidemic spread of a recombinant HIV-1 strain to viral natural history and vaccine development are discussed.

Africa↗
PubMed1995

Absence of point mutations in the extracellular domain of the alpha subunit of the GM-CSF receptor in a series of patients with acute myeloid leukemia (AML).

The GM-CSF receptor belongs to the cytokine receptor superfamily. The high-affinity receptors of this class are lacking intrinsic tyrosine kinase domains. The GM-CSF receptor consists of alpha and beta subunits. The beta subunit is shared with the receptors of IL-3 and IL-5. In addition to the membrane bound forms the receptors have been found to possess soluble isoforms. Since retroviral infection of the human GM-CSF dependent cell line, TF-1, leads to factor independent growth by increased expression of the GM-CSF receptor alpha chain in a subgroup of infected clones, we were interested in studying the role of this chain in human AML. Further considering that a point mutation in the extracellular domain of the erythropoietin receptor, also a member of the cytokine receptor superfamily, resulted in constitutive activation of a murine cell line, we investigated the possibility that a point mutation of the GM-CSF receptor was responsible for autonomous growth of AML cells. We sequenced a segment of the receptor coding for the extracellular domain of the alpha subunit. cDNA was prepared from peripheral blood or bone marrow cells from 24 patients with AML, from four patients with MDS and from three human myeloid cell lines. The region of interest was amplified with two rounds of PCR reactions with nested primers, covering five overlapping fragments, and directly sequenced using a non-radioactive technique. No point mutations were found in the investigated samples. Thus, point mutations in this segment of the GM-CSF receptor gene do not seem to play an important role in the transformation process of human acute leukemia.

Base Sequence↗
PubMed1994

What is a realistic frontal-offset test procedure?

With an increasing number of vehicles satisfying the FMVSS 208 Flat Barrier Impact Test and increasing belt usage, a high reduction of occupant injuries in general and a change from acceleration-induced to intrusion-induced injury mechanisms has been observed in Europe. The significance of intrusion-induced injury mechanisms associated with offset frontal impacts is assuming greater importance. Beginning in 1978, in response to this challenge, Mercedes-Benz has emphasized front structural countermeasures that have been found to be effective in the frequent asymmetrical frontal impacts. As an internal test, an offset impact with 40% overlap against a rigid barrier was defined. The relationship between actual accident frontal-overlap damage and barrier-test overlap values is explored in the paper. The results support the view that if a test of this type and associated design countermeasures were adopted by all vehicle manufacturers, a significant reduction of injuries would take place.

Accidents, Traffic↗
PubMed1993

Rapid transgene expression in lymphocyte and macrophage primary cultures after particle bombardment-mediated gene transfer.

A particle bombardment technique was used for gene transfer to human peripheral blood mononuclear cells, and murine splenocytes, thymocytes and peritoneal macrophages in primary culture. Significant expression of a luciferase marker gene was observed in these cell types within 8 h of gene transfer. Luciferase expression was readily detected in peritoneal macrophages 4 h after culture initiation and transfection. Same day determinations of transgene activity in fresh human peripheral blood mononuclear cell samples were feasible. Promoter preference and ballistic parameters were examined to optimize transgene expression. Up to 6% of bombarded human T lymphocytes expressed transgenic beta-galactosidase activity. These results demonstrate that particle bombardment is an effective means for gene transfer and provides an attractive approach for rapid, quantitative analysis of transgene expression in various leukocyte primary culture systems.

Animals↗
PubMed1991

Effects of chlorhexidine on proteolytic and glycosidic enzyme activities of dental plaque bacteria.

Chlorhexidine was tested for its ability to inhibit a wide range of glycosidic and proteolytic enzyme activities produced by Treponema denticola, Porphyromonas gingivalis, Bacteroides intermedius, Actinobacillus actinomycemcomitans, Capnocytophaga sputigena, Capnocytophaga gingivalis, Capnocytophaga orchracea, Capnocytophaga sp., Actinomyces viscosus, Streptococcus mitior, Streptococcus mutans, Streptococcus sobrinus, Streptococcus mitis, Streptococcus anginosus, Streptococcus oralis and Streptococcus sanguis. The enzymes produced by Capnocytophaga spp. were the most resistant to inhibition by chlorhexidine while the hydrolysis of proteolytic substrates by all the other species was markedly susceptible to inhibition with less than 0.125 mM chlorhexidine inhibiting enzyme activities by greater than or equal to 50%. Glycosidase activities, of all species, were generally more resistant to inhibition, especially neuraminidase activity. Chlorhexidine at less than 0.032 mM inhibited the degradation of bovine serum albumin by suspensions of dental plaque bacteria. These observations support an hypothesis that chlorhexidine exerts a bacteristatic effect in vivo, in part, by reducing the ability of dental plaque bacteria to degrade host-derived proteins and glycoproteins which normally provide essential nutrients for growth.

Acetylglucosaminidase↗
PubMed1991

Determination of the molecular structure of the human free secretory component.

Here, we present the experimental data, leading to determination of the primary structure, the linkage of the carbohydrates and the arrangements of the disulfide bonds of the human free secretory component. Methods of protein chemistry were used. The protein can be divided into five homology regions and is a member of the immunoglobulin superfamily.

Amino Acid Sequence↗
PubMed1990

Evidence that high mannose glycopeptides are able to functionally interact with recombinant tumor necrosis factor and recombinant interleukin 1.

Both recombinant tumor necrosis factor (rTNF) and recombinant interleukin 1 (rIL-1) are able to mediate vascular collapse and death in a previously described murine model, using galactosamine to enhance the toxicity of these cytokines. Unexpectedly, both acid-treated tumor necrosis factor (TNF) and a site-specifically mutagenized form of interleukin 1 (IL-1) (His-30----Arg-30), which fails to bind to the IL-1 receptor, retain full in vivo toxicity in this model of TNF- and IL-1-mediated shock. Previous studies have shown that rTNF and rIL-1 exhibit two functionally distinct binding regions. Both cytokines bind to their respective cell surface receptors and they also express lectin like binding specificity (Muchmore and Decker, J. Biol. Chem., 261: 13404-13407, 1986; Muchmore and Decker, J. Immunol., 138: 2541-2546, 1987) for defined oligosaccharides. The specificity of these two types of interactions is quite different. Cell surface receptors for IL-1 and TNF demonstrate essentially no cross-reactivity, whereas, in the case of carbohydrate binding, competition studies reveal an almost identical carbohydrate specificity for the structure Man5(6)GlcNAc2-Asn. Man5(6)GlcNAc2-Asn binding is either unaffected or actually enhanced by either acid treatment of rTNF or mutation at His-30 for rIL-1. Both deoxymannojirimycin and swainsonine, inhibitors of glycoprotein processing, raise intracellular levels of Man5-9GlcNAc2 and enhance the in vitro biological activity of both rTNF and rIL-1. Conversely, castanosperimine, a glucosidase I inhibitor which blocks the synthesis of mature high mannose structures, inhibits the biological activity of IL-1. These observations support the hypothesis that some effects of IL-1 and TNF may involve interaction with high mannose-substituted glycoproteins.

Animals↗
PubMed1990

Evidence that specific high-mannose oligosaccharides can directly inhibit antigen-driven T-cell responses.

Uromodulin is an 85 Kd immunosuppressive glycoprotein originally isolated from human pregnancy urine. It is unique in that most of its biologic activity can be attributed to attached oligosaccharides. Purified immunomodulatory oligosaccharides from uromodulin have been structurally characterized using 1H-NMR spectroscopy and shown to be Man6-7GlcNAc2(M6,M7). Based on these observations, we isolated high-mannose N-type oligosaccharides and glycopeptides from ovalbumin, soybean agglutinin, and yeast mannan and show that these high-mannose compounds directly inhibit in vitro antigen-driven T-cell proliferation from millimolar to nanomolar concentrations. The most active compound was a core mannose oligosaccharide derived from yeast mannan, M9(y), which acts to block early events required for normal antigen processing/presentation. These data emphasize the potential functional role of carbohydrate structure in regulating the human immune response.

Antigens↗
PubMed1989

SPARC: a Ca2+-binding extracellular protein associated with endothelial cell injury and proliferation.

SPARC (Secreted Protein that is Acidic and Rich in Cysteine) is a Ca2+-binding, stress-related protein released in vitro by both malignant and normal cells derived from all primordial germ layers. It is specifically elevated in endothelial cells as a result of "culture shock" (characterized by high levels of proliferation and migration) and exhibits density-dependent secretion. Exposure of bovine aortic endothelial cells to endotoxin results in a 70-100% increase in secreted protein, with a three-fold increase in SPARC. Immunofluorescence histochemistry on mouse tissues revealed (a) a preferential association of SPARC with highly proliferative cells (e.g., gut epithelia, mammary gland, and epidermis), (b) a cell surface or stromal location in thymus, lung, and salivary gland, (c) staining of epididymidal epithelium and testicular cells, and (d) an association with somites of 14 d mouse embryos. We envision SPARC as an extracellular modulator of Ca2+ and other cation-sensitive proteins/proteinases, that facilitates cellular proliferation in response to injury and to developmental signals.

Animals↗
PubMed1989

Distribution of the calcium-binding protein SPARC in tissues of embryonic and adult mice.

SPARC (Secreted Protein that is Acidic and Rich in Cysteine), a Ca++-binding glycoprotein also known as osteonectin, is produced in significant amounts by injured or proliferating cells in vitro. To elucidate the possible function of SPARC in growth and remodeling, we examined its distribution in embryonic and adult murine tissues. Immunohistochemistry on adult mouse tissues revealed a preferential association of SPARC protein with epithelia exhibiting high rates of turnover (gut, skin, and glandular tissue). Fetal tissues containing high levels of SPARC included heart, thymus, lung, and gut. In the 14-18-day developing fetus, SPARC expression was particularly enhanced in areas undergoing chondrogenesis, osteogenesis, and somitogenesis, whereas 10-day embryos exhibited selective staining for this protein in Reichert's membrane, maternal sinuses, and trophoblastic giant cells. SPARC displayed a Ca++-dependent affinity for hydrophobic surfaces and was not incorporated into the extracellular matrix produced by cells in vitro. We propose that in some tissues SPARC associates with cell surfaces to facilitate proliferation during embryonic morphogenesis and normal cell turnover in the adult.

Animals↗
PubMed1988

Motor organization of the spinal accessory nerve in the monkey.

The segmental and topographical organization of motoneurons of the spinal accessory nerve was studied in monkeys with horseradish peroxidase (HRP). The sternomastoid muscle is innervated primarily from the C1-C2 level of the cord and the motor column is medial in the ventral horn. The trapezius muscle, however, is innervated primarily from the C2-C3-C4 levels of the cord and the motor column lies in the ventrolateral region of the ventral horn. The data are discussed with regard to treatment of torticollis.

Animals↗
PubMed1985

Pseudomonas dermatitis associated with a swimming pool.

One hundred forty-seven (66%) of 224 scouts and chaperons were interviewed after a weekend visit to a dude ranch in upstate New York. One hundred seventeen (80%) complained of papular rashes or eye and ear inflammation. Onset of illness occurred within 24 to 48 hours of arrival at the ranch. After controlling for participation in other available activities, only swimming was found to be associated with illness. Pseudomonas aeruginosa serotype 0 11 grew from a culture of pool water and from 17 cultures of skin, eye, and ear lesions in visitors to the ranch. Follow-up was obtained for 76 of the affected persons for whom initial information was available. Mean duration of illness was 14.5 days (range, one to 40+ days). The recurrence rate was 24%.

Adult↗
PubMed1984

[The primary structure of human free secretory component and the arrangement of disulfide bonds].

The amino-acid sequence and the arrangement of the disulfide bonds of the human free secretory component were completely elucidated by the methods of protein chemistry. The free secretory component is a monomeric glycoprotein (Mr approximately 86000), consisting of 558 amino acids with 7 carbohydrate chains bound to asparagine. The protein contains 20 cysteine residues but, as a special feature, no methionine. The polypeptide chain is divided into five regions of internal homology, 104 to 114 amino acids in length. The 20 cysteine residues form 10 disulfide bonds, 9 of which confirm the internal homology by their characteristic arrangement. The free secretory component also shows homology to immunoglobulins in some sections. A computer-supported tertiary structure is proposed for the free secretory component.

Amino Acid Sequence↗
PubMed1979

A receptor for IgA on human T lymphocytes.

Receptors for IgA antibody-antigen complexes were demonstrated on 2 to 18% (mean 6.7%) of human peripheral blood T cells. The proportion of cells bearing detectable IgA receptors was low in freshly prepared T cells and increased in number after 18 to 24 hr of culture similar to the time course of appearance of the Tmu receptor. These T receptors were shown to be distinctly different from Fc-IgM and Fc-IgG receptors on T cells by blocking studies with purified IgA, IgG, and IgM.

Animals↗