Natural killer (NK) activity is mediated by a small population of peripheral blood cells that exhibit the homogeneous morphology of large granular lymphocytes (LGL). In recent studies, human NK cell clones have been shown to contain a 200,000-Mr (relative molecular mass) protease-resistant chondroitin sulphate A proteoglycan, which has been localized to the secretory granule by X-ray dispersive analysis and by its resistance to cleavage by extracellular addition of chondroitinase AC or ABC (ref. 7). In the present study, we have used six different human NK cell clones to demonstrate that release of 35S-proteoglycan correlates closely with cytolytic activity against various NK cell targets. When NK activity is blocked by monoclonal antibodies at either the effector cell level (LFA-1) or at the target cell level (TNKTAR), there is a concomitant decrease in exocytosis of proteoglycan. Monoclonal antibodies directed against recognition structures, for example anti-NKTa and anti-T3 (ref. 10), function as soluble stimuli, capable of initiating the release of 35S-proteoglycan. Taken together, these results provide strong evidence for the stimulus-specific release of chondroitin sulphate A proteoglycans from NK cells when the cytolytic process is activated.

Antibodies, Monoclonal↗

PubMedDate not supplied

The CT halo sign: a new finding in intestinal lymphangiectasia.

A "halo sign" has been described in patients with Crohn disease, ulcerative colitis, radiation enteritis, ischemic colitis, and pseudomembranous colitis. This sign is characterized by an inner ring of low CT attenuation surrounded by a higher attenuation outer ring. We present a patient with primary intestinal lymphangiectasia in whom CT demonstrated a halo sign correlated with mucosal biopsy.

Adult↗

PubMedDate not supplied

Biological changes in the annulus fibrosus in patients with low-back pain.

The anterior annulus from patients undergoing surgery for low-back pain was compared with the same region removed at autopsy. Collagen, proteoglycan, and water content were measured in different regions across the annulus. Water and proteoglycan contents increased from the outer to the inner annulus, whereas the collagen contents declined. Quantitative differences were found between agematched surgical and autopsy specimens. Discs from most patients showed lowered proteoglycan contents, and a few of these showed high water contents. Loss of collagen in isolated areas of the annulus was demonstrated in some patients. Collagen loss occurred most frequently in the lumbosacral disc, whereas changes in proteoglycan and water were more frequent higher in the lumbar region. No qualitative changes in collagen types were detected immunochemically. In many patients, the levels of proteoglycan which aggregated in vitro were extremely low. Changes in hexosamine molar ratio of disc proteoglycan and in the length of the chondroitin sulfate side chains were observed with aging in this group of patients.

Acetylglucosaminidase↗

PubMedDate not supplied

Cloning of the human homolog of mouse transmembrane tryptase.

BACKGROUND: Three functionally distinct tryptases have been identified in the mouse, one of which encodes an unusual protease that possesses a membrane-spanning domain located in its C terminus. METHODS AND RESULTS: Using the deduced nucleotide sequence of this mouse transmembrane tryptase (mTMT) gene in a polymerase chain reaction approach, cDNAs were isolated from a number of tissues which encode its human homolog. The amino acid sequences of hTMT and mTMT are 74% identical, and the human tryptase also has the novel membrane-spanning domain. CONCLUSION: The discovery that the human genome contains a large number of homologous, but distinct, tryptase genes suggests that the individual members of this family of proteases evolved to carry out discrete functions in mast cell-mediated allergic reactions.

Amino Acid Sequence↗

PubMedDate not supplied

Coupling efficiencies of amino acids in the solid phase synthesis of peptides.

The "classical" Merrifield method was used to synthesize over 500 peptides using Boc-benzyl strategy. The peptides were prepared either manually or on a Beckman 990B synthesizer or an Applied Biosystems 430A synthesizer. Each coupling of Boc amino acid to the growing peptide on the resin was monitored with the ninhydrin reaction. Couplings were considered "incomplete" if there was 99% or less coupling and "high incomplete" if there was 98% or less coupling. The efficiency of coupling was evaluated in regard to the specific amino acids involved in the coupling reaction and to the length of the peptide at the time of the coupling. The most difficult carboxyl-reacting amino acids were histidine, threonine, arginine, valine, isoleucine and glutamine; the most difficult amine reacting residues were glutamine, leucine, alanine, arginine and isoleucine. The number of "incomplete" and "high incomplete" couplings and the total number of monitored couplings of each of the 20 carboxyl-reacting amino acids when reacting with each of the 20 amine-reacting residues were tabulated. Coupling efficiencies decreased with the length of the peptide. The conclusion of this study is that, with the chemistries and methods used in this group of peptides, no amino acid coupling can be predicted to be complete with a single coupling reaction. The study points to the need for on-line determination of coupling efficiency during the synthesis in which a recoupling step is initiated when the first coupling is incomplete.

Amino Acids↗