Search

A single amino acid substitution between Asn and Ser at position 631 in the chicken Mx protein has been reported to determine resistant and sensitive antiviral activity. In this study, we investigate whether various kinds of chicken breeds and jungle fowls carry the resistant or sensitive Mx allelic gene by using the mismatched PCR-restriction fragment length polymorphism (RFLP) technique. In total, 271 samples from 36 strains of 17 chicken breeds and from 3 kinds of jungle fowls were examined. The rates of the resistant Mx gene and sensitive gene were 59.2% and 40.8%, respectively. Only a Red jungle fowl captured in Laos carried the resistant Mx gene, and the other three Red jungle fowls from Indonesia and Gray and Green jungle fowls all had the sensitive Mx gene. These results were confirmed by the determination of amino acid sequences in the GTPase effector domain of jungle fowls.

To elucidate photosensitization potentials of new quinolone antibacterial agents, production of active oxygen species and peroxidation of squalene after ultraviolet A exposure were investigated. Production of singlet oxygen and/or hydrogen peroxide was estimated by bleaching of p‐nitroso‐N, N‐dimethylaniline. Lomefloxacin showed the greatest ability to produce active oxygen species, and this ability was reduced by the addition of the singlet oxygen quencher sodium azide. Ciprofloxacin and fleroxacin also had strong activity. Photosensitized peroxidation of squalene was evaluated by measurement of thiobarbituric acid‐reactive substances. Lomefloxacin was the strongest sensitizer, followed by fleroxacin and ciprofloxacin. These results suggest that certain new quinolones are involved in phototoxicity via the mechanism of active oxygen species.

We studied selective elimination of β2 -microglobulin(β 2-m) from plasma of patients with chronic renal failure(CRF) by using immunoadsorption method.Anti-human β2-m antibody of rabbit IgG was coated with cellulose beads, which were filled into a small-column. One gm of cellulose beads contains 5.0 mg of the protein of antibody. Five to 7 ml of plasma samples with 40 to 70 mg/l of β2-m were passed through the column at 1.0 ml/10 min and each effluent was then collected by 1.0 ml consecutively. Before and after passing through the column, β2-m and other plasma proteins were measured. Plasma β2-m concentrations in all the effluent fractions after passing through the column were greatly reduced to 1/100. But no other plasma protein components than β2-m varied in concentration. Neither Immune complex (IC) nor rabbit IgG was detected in any effluent fraction.These results indicate that selective and effective elimination of β2-m from plasma in patients with CRF was possible by using our method. In addition, since neither IC nor rabbit IgG was detected in the effluent, this method was considered to be clinically applicable.

We obtained human T-cell hybridomas that are specific for bee venom phospholipase A2 (PLA2) and constitutively secrete glycosylation inhibiting factor (GIF). Upon crosslinking of CD3, the hybridoma produced GIF having affinity for PLA2. When affinity-purified PLA2-binding GIF was used as an immunogen, monoclonal antibodies specific for the antigen-binding GIF were obtained. Monoclonal antibody 110BH3 bound the antigen-binding GIF but failed to bind the 13-kDa nonspecific GIF, as determined by both bioassay and ELISA. In contrast, 388F1, a monoclonal antibody against nonspecific GIF, gave ELISA signals with both the nonspecific GIF and the antigen-binding GIF. Gel filtration of affinity-purified antigen-binding GIF revealed the presence of a 72- to 80-kDa protein which gave ELISA signals with both 110BH3 and 388F1 and contained GIF bioactivity. Upon reduction and alkylation, the antigen-binding GIF dissociated into a 62- to 64-kDa protein which gave positive ELISA with antibody 110BH3 but no signal with antibody 388F1, and a 15-kDa protein, which gave ELISA signal with the 388F1 but not with 110BH3. Immunoblotting of a PLA2-binding GIF preparation revealed that under reducing conditions, the antigen-binding GIF dissociated a 13-kDa peptide which reacted with polyclonal antibodies against recombinant GIF. The results indicate that the 13-kDa nonspecific GIF is a subunit of antigen-binding GIF. The PLA2-binding GIF has affinity for an epitope, representing amino acid residues 19-28 in PLA2 which appears to be an external structure in the antigen.

The beta-amyloid peptide, which forms extracellular cerebral deposits in Alzheimer's disease, is derived from a large membrane-spanning glycoprotein referred to as the beta-amyloid precursor protein (APP). The APP is normally cleaved within the beta-amyloid region by a putative proteinase (alpha-secretase) to generate large soluble amino-terminal derivatives of APP, and this event prevents the beta-amyloid peptide formation. It has been suggested that the gelatinase A (matrix metalloproteinase 2, a 72-kDa type IV collagenase) may act either as alpha-secretase or as beta-secretase. Mice devoid of gelatinase A generated by gene targeting develop normally, except for a subtle delay in their growth, thus providing a useful system to examine the role of gelatinase A in the cleavage and secretion of APP in vivo. We show here that APP is cleaved within the beta-amyloid region and secreted into the extracellular milieu of brain and cultured fibroblasts without gelatinase A activity. The data suggest that gelatinase A does not play an essential role in the generation and release of soluble derivatives of APP at physiological conditions.

By using probes based on partial amino acid sequence of glycosylation-inhibiting factor (GIF) from a mouse T-cell hybridoma, a full-length cDNA encoding mouse GIF was isolated. A cDNA clone encoding human GIF was isolated from cDNA libraries of a GIF-producing human T-cell hybridoma by using mouse GIF cDNA as a probe. The cDNAs encode a putative 12.5-kDa peptide of 115 amino acids. Northern blot analysis demonstrated a single, 0.6-kb transcript. Polyclonal rabbit antibodies against the Escherichia coli-derived recombinant 13-kDa peptide bound hybridoma-derived GIF. Although the peptide did not contain a signal peptide sequence, transfection of the cDNA into COS-1 cells resulted in secretion of 13-kDa peptide, but the peptide had substantially less bioactivity than the hybridoma-derived GIF. However, expression of a chimeric cDNA encoding a fusion protein consisting of the N-terminal pro region of calcitonin precursor and human GIF and cotransfection with furin cDNA to allow intracellular cleavage of the fusion protein resulted in secretion of 13-kDa peptide that was comparable to hybridoma-derived GIF in its bioactivity. Both the 13-kDa peptide and GIF bioactivity in the transfected COS-1 supernatant bound to a monoclonal antibody against hybridoma-derived human GIF. These results indicate that the 13-kDa peptide represents recombinant GIF, but posttranslational modification of the peptide is important for generation of the bioactivity. The GIF cDNA had high homology with the cDNA encoding macrophage migration inhibitory factor. However, the recombinant GIF failed to inhibit migration of human monocytes, and recombinant human macrophage migration inhibitory factor did not have GIF bioactivity.

Protein G, a bacterial cell-wall protein with high affinity for the constant region of IgG (IgGFc) antibodies, contains homologous repeats responsible for the interaction with IgGFc. A synthetic peptide corresponding to an 11-amino acid-long sequence in the COOH-terminal region of the repeats was found to bind to IgGFc and block the interaction with protein G. Moreover, two other IgGFc-binding bacterial proteins (proteins A and H), which do not contain any sequences homologous to the peptide, were also inhibited in their interactions with IgGFc by the peptide. Finally, a decapeptide based on a sequence in IgGFc blocked the binding of all three proteins to IgGFc. This unusually clear example of convergent evolution emphasizes the complexity of protein-protein interactions and suggests that bacterial surface-protein interaction with host protein adds selective advantages to the microorganism.