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Biomedical subjects

A R Brown

Publications and source records attributed to A R Brown.

At least 91 records · Page 5Linked to original sources

Antigen- and receptor-driven regulatory mechanisms. III. Induction of delayed type hypersensitivity to azobenzenearsonate with anti-cross-reactive idiotypic antibodies.

Delayed-type hypersensitivity (DTH) to p-azobenzenearsonate (ABA) can be induced in A/J mice with intravenous injection of minute amounts of anti-cross-reactive idiotypic (CRI) antibodies, providing that the animals have been pretreated 2 d earlier with low doses of cyclophosphamide (50 mg/kg). However intravenous injection of the F(ab')2 fragments of the anti-CRI antibodies or subcutaneous administration with anti-CRI antibodies induces comparable immunity in both cyclophosphamide-pretreated and normal nontreated animals. Furthermore adoptive transfer experiments indicate that lymph node cells taken from animals sensitized with anti-CRI 4 d earlier can adoptively transfer immunity to naive recipients. Transfer of immunity is mediated by a population of thymus-dependent (T) cells, which express idiotypic structures on their surface. Treatment of effector cells with either anti-theta serum or anti-idiotypic antibodies plus complement completely abrogated their ability to transfer immunity. In addition idiotype-bearing suppressor T cells induced with ABA-coupled spleen cells inhibit the development of ABA-specific DTH induced with anti-CRI antibodies. Genetic analysis revealed that the ability of anti-CRI antibodies to induce ABA-specific DTH was linked to Igh-1 heavy-chain allotype. Anti-idiotypic antibodies to the major CRI associated with anti-ABA antibodies in A/J mice failed to induce significant immunity in BALB/c mice (H-2d, Igh-1a). Nevertheless, they were able to induce significant immunity in C.AL20 mice (H-2d, Igh-1d) which possess a heavy-chain allotype similar to that of A/J mice.

Animals↗

Dominance of an immune response by secondary cells: quantitation by allotype analysis.

Dominance of an immune response by secondary cells was demonstrated in a cell transfer system utilizing allotype-congenic mice. Spleen cells from BALB/c mice immunized with TNP-KLH were adoptively transferred into sublethally irradiation (200 R) congenic partners of a different allotype (C.B.-17 mice). Subsequent to the cell transfer, the recipients were challenged with TNP-KLH and bled periodically. Anti-TNP antibodies were isolated and analyzed for their content of donor and host IgG allotypes. Through day 58 after the adoptive transfer, 80% or more of the IgG antibody measured was of donor allotype. By day 110, most but not all recipients made IgG antibody principally of host allotype. In contrast, control C.B-17 recipients, which received nonimmune BALB/c spleen cells but otherwise treated as above, produced IgG antibodies almost entirely of host allotype. Total anti-TNP synthesis was reduced markedly in recipients of immune BALB/c cells so that there was a decrease of about 95% in the production of anti-TNP antibodies of host allotype, as compared with controls that received nonimmune cells. The results are discussed in terms of dominance of an immune response by secondary B cells.

Animals↗

A phosphorylcholine idiotype related to TEPC 15 in mice infected with Ascaris suum.

A serum component, binding antigens having phosphorylcholine (PC) determinants were induced in several strains of mice by infection with Ascaris suum. This component was isolated and demonstrated to be an IgM (K) anti-PC antibody having idiotypic determinants in common with the IgA PC-binding myeloma protein TEPC 15. Rabbit anti-idiotypic antisera prepared with this component had idiotypic specificity for TEPC 15 and cross-idiotypic recognition of MOPC 167 and McPC 603, all IgA PC-binding myeloma proteins. The antisera also recognized determinants not present on TEPC 15. IgM and idiotype levels were quantitated by radial immunodiffusion and PC-specific antibody measured by hemagglutination (HA) with sheep erythrocytes coated with pneumococcal-C-polysaccharide. Mean IgM levels ranged from 2.5 to 8.7 mg/ml, idiotype from 0.54 to 5.3 mg/ml; and HA titers from 1:512 to 1:130,000 in different mouse strains. The high PC-specific antibody response was not duplicated by immunization with dead ascaris larvae or by infection with two other nematode species.

Animals↗

The total chemical synthesis of monocyte chemotactic protein-1 (MCP-1).

The affinity-based N (alpha)-amino protecting group tetrabenzo[a,c,g,i]fluorenyl-17 methoxycarbonyl (Tbfmoc) has been utilized as a hydrophobic probe to allow the simple, quick and highly effective isolation of a 76 residue cysteine-containing protein (MCP-1). The base-labile Tbfmoc group can be removed under very mild conditions, which preserve the thiol-containing protein in the reduced state. Oxidative folding was then used to furnish the biologically active beta-chemokine MCP-1.

Amino Acid Sequence↗

Percutaneous control of a portacaval H-graft: description of a new device and its initial clinical application.

A percutaneously-controlled inflatable cuff which can change the diameter of a portacaval H-graft has been developed and used in 10 patients. When inflated, the cuff narrows the H-graft to increase portal pressure and reduce shunting. Use of the cuff has been of clinical significance in 3 of 7 long-term surviving patients. Narrowing the shunt improved the clinical state in 2 patients with encephalopathy, and reopening a closed shunt improved ascites in the third patient. Duplex ultrasound and deep Doppler have demonstrated an alteration of hepatic portal blood flow following inflation of the cuff after 6 months. It is concluded that further development of this controlled portacaval H-graft is warranted.

Adult↗

Propellant-driven aerosols of functional proteins as potential therapeutic agents in the respiratory tract.

Aerosols of respirable-sized particles of functional proteins were delivered by volatile propellant from metered-dose aerosol canisters. The enzyme alkaline-phosphatase and a monoclonal antibody were lyophilized with surfactant and suspended in the aerosol propellant dimethylether. As much as 20 micrograms of functional protein, assessed by enzyme function or antibody binding activity, was delivered per 40 microliters of released propellant. Up to 25% of the protein was of respirable size (< or = 4 microns mass median aerodynamic diameter) when aerosolized proteins were sampled with a Casella cyclone. Respirable particles were derived from visible surfactant/protein complexes suspended in the liquified propellant and from propellant-soluble, nonsedimentable, surfactant/protein molecules that are probably reverse micelles. 10-14 days of propellant exposure in dimethylether increased protein solubility in the propellant, increased the total protein aerosolized and maintained or increased the quantity of respirable-sized protein molecules, as compared to the day aerosol vials were charged with propellant. Scanning electron microscopic studies of the respirable-sized protein/surfactant particles showed that they ranged in size from 0.07 to 3.25 microns in diameter, and they appeared to be chain aggregates of spherical subunits, 0.11 to 0.93 microns in diameter. This structural motif was common to both proteins. The possibility of delivering immunizing antigens, cytokines, passive antibodies and other therapeutic proteins to the respiratory tract using propellant-driven aerosols is discussed.

Aerosol Propellants↗

Expression of the intracisternal A particle endogenous retrovirus genes over the lifetime of mouse and Syrian hamster.

Transcription of intracisternal A particle genes in several tissues has been examined throughout the lifespan of inbred C57BL/6J and outbred wild-type mice and golden Syrian hamster. In both rodent species, expression of the genes occurs at all ages and in all tissues. Also, in both species, RNA transcripts of heterogeneous lengths are found that correspond in size not only to the proviral genes previously characterized but also to genes larger than those reported. In hamster, the size heterogeneity is more extensive than in the mouse, where discrete size transcripts are detectable over the heterogeneous signal. Transcription of these genes throughout the lifespan is not peculiar to the hamster or inbred laboratory mouse strain (C57BL/6J) but also occurs in many tissues of outbred wild-type Mus musculus at each age examined. Lifelong transcription of intracisternal A particle retrovirus genes raises the suggestion that retrovirus proteins and cDNA are continuously produced and could facilitate cumulative genomic rearrangements. This could lead to improper gene regulation and thus contribute to the age-dependent increase of cancer and more generally to the aging process itself.

Journal Article↗