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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

From these data, a model was prepared which summarizes schematically our present knowledge of the structure and orientation of the HL-A antigenic molecule in the lymphocyte membrane (Fig. 3). It seems likely that the heavy chain spans the membrane, with the hydrophobic region inserted in the membrane and the hydrophilic C-terminus inside the cell. This C-terminal region bears one (possible two) SH residue which has the potential for forming interchain disulfides. Whether or not these are actually formed physiologically remains an interesting question. There is the attractive possibility that whatever the physiological functions of HL-A antigens are, structurally these molecules provide the potential for signaling from outside the cell to inside the cell because they span the membrane. It is even conceivable that this function might be expressed via the opening and closing of disulfide bridges.
Cold Spring Harb Symp Quant Biol 1977
PMID:Structure of HL-A A and B antigens isolated from cultured human lymphocytes. 33 91

A strategy for the proteolytic fragmentation of human IgM has been developed. This method is called "cold pepsin digestion" because of its unique feature of achieving restricted peptic cleavages at 4 degrees and pH 4.0. Cold pepsin digestion has been applied successfully to produce an Fv fragment from 14 human IgM proteins. The Fv fragment consists of the heavy chain variable domain (VH) and the light chain variable domain (VL) held together by strong noncovalent interaction. Thus, each Fv fragment contains one intact antigen-binding site and represents the minimal active fragment derivable from an antibody molecule. A series of other structurally and functionally important fragments were also isolated and characterized. Two basic digestion pathways were recognized; these mainly reflect the relative accessibility of five sets of major interdomain cleavage sites.
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PMID:Cold pepsin digestion: a novel method to produce the Fv fragment from human immunoglobulin M. 35 13

Antigen-binding receptors of T lymphocytes were analyzed in two different ways. First, the idiotypic properties of T helper cells are studied using anti-idiotypic antisera prepared against isolated antibodies specific for A-CHO. These anti-idiotypic antisera are defined by immunogenetic and immunochemical means with respect to their reactivity with heavy- or light-chain-associated idiotypic determinants. Second, antigen-binding receptors are isolated from enriched T-and B-lymphocyte preparations and compared with respect to their reactivity with antigen and with class- or allotype-specific anti-Ig antisera. The results provide an incomplete picture of the T-cell receptor which shares with antibodies the variable region of the heavy chain but probably no other variable or constant portion.
Cold Spring Harb Symp Quant Biol 1977
PMID:On the structure of the T-cell receptor for antigen. 40 92

It has been found that a high-speed supernatant fraction from Xenopus oocytes extracted in the cold will form a clear, solid gel upon warming. Gel formation occurs within 60 min at 18 degrees-40 degrees C, and is, at least initially, temperature reversible. Gelation is strictly dependent upon the addition of sucrose to the extraction medium. When isolated in the presence of ATP, the gel consists principally of a 43,000-dalton protein which co-migrates with Xenopus skeletal muscle actin on SDS-polyacrylamide gels, and a prominent high molecular weight component of approx. 250,000 daltons. At least two minor components of intermediate molecular weight are also found associated with the gel in variable quantities. Actin has been identified as the major consituent of the gel by ultrastructural and immunological techniques, and comprises roughly 47% of protein in the complex. With time, the gel spontaneously contracts to form a small dense aggregate. Contraction requires ATP. In the absence of exogenous ATP, a polypeptide which co-migrates with the heavy chain of Xenopus skeletal muscle myosin becomes a prominent component of the gel. This polypeptide is virtually absent from gels which have contracted in ATP-containing extracts. It has also been found that Ca++ is required for gelation in oocyte extracts. At both low and high concentrations of Ca++ (defined as a ratio of Ca++/EGTA in the extraction medium), gelation is inhibited.
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PMID:Actin in Xenopus oocytes. 56 81

Bovine factor Va has been previously been shown to consist of heavy (M(r) = 94,000) and light chains (M(r) = 81,000), that interact in a manner dependent upon the presence of either calcium or manganese ions. In an attempt to understand the mechanism of subunit interaction we have studied the effects of temperature and ions on factor Va stability. The rates of formation of factor Va from isolated chains and dissociation were temperature-dependent with an energy of activation of 6.2 and 1.3 kcal mol-1, respectively. The yield of factor Va from isolated chains was inversely related to the amount of time the chains were incubated at 4 degrees C. Incubation of individual chains revealed that the heavy chain is cold-labile, an effect that is reversible. Manganese ion was observed to prevent the conversion to the inactive form. High salt tends to stabilize the two-chain structure of factor Va, but is inhibitory to its formation from isolated chains. High concentrations of either manganese or calcium ions also inhibited reconstitution of activity. The light chain, in particular, was sensitive to the presence of manganese or calcium ion. Heavy chain that had been cleaved by activated protein C had a weakened interaction with the light chain, and the resulting complex had no procoagulant activity. Cooling of the heavy chain to 4 degrees C enhanced its intrinsic fluorescence. Manganese ion prevented some of this enhancement. The heavy chain fluorescence returned to the room temperature value with a half-life of approximately 10 min. In the presence of manganese ion relaxation was accelerated. The intrinsic fluorescence of activated protein C-cleaved heavy chain was not increased when the temperature was decreased. These data suggest that the heavy chain can exist in two forms. Elevated temperature converts it to a form that can bind ions and have a productive interaction with the light chain. However, conditions that prevent the heavy chain from combining with the light chain also stabilize the two subunit structure, suggesting that the high affinity of the complex is due to conformational changes that occur after chain interaction.
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PMID:Characterization of the interaction between the heavy and light chains of bovine factor Va. 140 Mar 6

The F105 mAb, identified in an HIV-1-infected individual, binds to a discontinuous epitope on the HIV-1 gp120 envelope glycoprotein, blocks the binding of gp120 to the CD4 viral receptor, and neutralizes a broad range of HIV-1 isolates. This study reports the primary nucleotide and deduced amino acid sequences of the rearranged heavy and light chains of the mAb F105. This IgG1k mAb uses a VH gene member of the VH4 gene family (V71-4) and is productively rearranged with a D-D fusion product of the dlr4 and da4 germline DH genes and the JH5 gene. This rearranged heavy chain gene expresses the VH4-HV2a idiotope, which is seen in human monoclonal IgM cold agglutinins. The F105 Vk appears to be derived from the Humvk325 germline gene and is rearranged with a Jk2 gene. For both chains, the mutational pattern in the rearranged VH and VL genes is indicative of an antigen-driven process. These studies show that production of a broadly neutralizing anti-HIV-1 antibody that recognizes determinants within the CD4 recognition site of the envelope glycoprotein is achieved by rearrangement of the V71-4 and Humvk325 germline variable region genes along with selected individual point mutations in the rearranged genes.
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PMID:Characterization of the cDNA of a broadly reactive neutralizing human anti-gp120 monoclonal antibody. 140 Oct 79

A solid aluminum block, connected with a warm and cold thermostated waterbath, provided for a linear transversal temperature gradient (TG) during polyacrylamide gel electrophoresis (PAGE). Noncovalently bound heavy chain dimers as well as heavy-light chain dimers, derived from human monoclonal IgG, could be melted into monomers using a 40-75 degrees C TG under conditions of sodium dodecyl sulfate-PAGE. Using native PAGE, major histocompatibility complex (MHC) class I molecules, preloaded with the iodinated peptide FAPGNYPAL could be melted in a 4-40 degrees C TG to release the peptide. The method is in general applicable to thermal stability analysis of noncovalently bound hetero-oligomers if the product after melting possess different electrophoretic mobilities.
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PMID:Analysis of members of the Ig-gene superfamily by thermal gradient polyacrylamide gel electrophoresis. 145 86

To investigate the molecular basis of the autoimmune response to the related i and I carbohydrate antigens, we studied cold agglutinins (CA) from B-cell clones and from the peripheral circulation of patients with lymphoproliferative syndromes. Sequence analyses of expressed variable region genes indicate that both anti-i and anti-I specificities from B-cell clones from two patients are encoded by the VH4.21 or a very closely related VH4 heavy chain gene, whereas the expressed light chain genes differed. The anti-i-secreting B-cells express unmutated germline-encoded VH4.21 and VKI gene sequences. The VH region gene encoding anti-I has the closest homology (97%) to the VH4.21 germline gene and differs at the protein level by only three amino acids. In contrast, while the VL region gene encoding anti-I is most homologous (96%) to the VKIII, kv328 germline gene, there are seven amino acid differences due to nonrandom replacement mutations, which suggests a role for antigen-mediated selection in the anti-I response of this individual. These studies were extended by a structural survey of 20 additional serum CA using antipeptide antibodies specific for determinants in VH and VL regions. All anti-I and anti-i CA were shown to express VH4 heavy chains, and 14 of 17 CA expressed a previously described VH4 second hypervariable region determinant, termed VH4-HV2a. We also found that 13 of 14 anti-I CA used VKIII light chains, while the anti-i CA used light chains from at least three VL families. Taken together, the data show that anti-i and anti-I CA probably both derive from the VH4.21 gene (or a closely related gene). Furthermore, the restricted VH and different VL gene use in anti-i and anti-I CA may reflect the close structural relationship of the i and I antigens.
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PMID:Variable region gene analysis of pathologic human autoantibodies to the related i and I red blood cell antigens. 165 49

A subclone of rat pheochromocytoma cells expresses high affinity receptors for tetanus toxin on differentiation with NGF [Walton, K.M., Sandberg, K., Rogers, T.B. and Schnaar, R.L. (1988) J. Biol. Chem. 263, 2055-2063]. In the presence of protein cross-linking agents, [125I]tetanus toxin, bound to these cells at 0 degree C, forms a cross-linked product with apparent molecular weight of 120 kDa. The formation of [125I]tetanus toxin conjugate involves the heavy chain of the toxin, is prevented by cold toxin and it is largely reduced by pretreating cells with proteases. The cross-linked product is formed only upon incubation of the toxin with NGF-differentiated cells. These results suggest that a protein with apparent molecular weight of 20 kDa is involved in the neurospecific binding of tetanus toxin.
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PMID:Tetanus toxin receptor. Specific cross-linking of tetanus toxin to a protein of NGF-differentiated PC 12 cells. 191 81

The ability of recombinant interleukin 2 (rIL2) activated lymphocytes (LAK) to purge BM samples contaminated by tumour cells was evaluated. Human BM mononuclear cells were contaminated with 10% of the lymphoma line CA46 and then cultured in liquid medium containing 1000 U/ml of rIL2 and/or LAK autologous to the used BM. At the end of coculture the growth of residual tumour cells and of CFU-GM were evaluated by clonogenic assay. No tumour cell growth was observed in 5/5 independent experiments after 18 h of coculture with LAK. No significant inhibition of CFU-GM growth was also noted. Subsequently, the effect of LAK on BM obtained from four leukaemic patients and contaminated with 20-50% of their own AML and ALL cells was studied using MAb as a tool for identifying leukaemic cells. LAK eliminated 24-78% of contaminating cryopreserved uncultured autologous leukaemic cells. In five cases the BM was contaminated by a low (2%) amount of ALL cells. In these patients the monoclonal heavy chain rearrangement typical of ALL was no longer visible after coculture with LAK. Evidence for selective tumour cytotoxicity by LAK was confirmed by using autologous BM cells as hot and cold targets in a 51Cr release assay. Finally, successful haematologic reconstitution of lethally irradiated BALB/c mice was obtained using syngeneic BM cocultured with LAK. These results support the investigational use of rIL2 and LAK in the treatment of human leukaemia.
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PMID:Selective purging by human interleukin-2 activated lymphocytes of bone marrows contaminated with a lymphoma line or autologous leukaemic cells. 206 57


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