Mechanism of action of transmembrane activator and calcium modulator ligand interactor-Ig in murine systemic lupus erythematosus

B cell-activating factor belonging to the TNF family (BAFF) blockade prevents the onset of disease in systemic lupus erythematosus (SLE)-prone NZB/NZW F(1) mice. To determine the mechanism of this effect, we administered a short course of TACI-Ig with and without six doses of CTLA4-Ig to 18- to 20-wk-old NZB/NZW F(1) mice and evaluated the effect on B and T cell subsets and on anti-dsDNA Ab-producing B cells. Even a brief exposure to TACI-Ig had a beneficial effect on murine SLE; CTLA4-Ig potentiated this effect. The combination of TACI-Ig and CTLA4-Ig resulted in a temporary decrease in serum IgG levels. However, after cessation of treatment, high titers of IgG anti-dsDNA Abs appeared in the serum and IgG Abs deposited in the kidneys. Despite the appearance of pathogenic autoantibodies, the onset of proteinuria was markedly delayed; this was associated with prolonged depletion of B cells past the T1 stage, a decrease in the size of the spleen and lymph nodes, and a decrease in the absolute number of activated and memory CD4(+) T cells. TACI-Ig treatment normalized serum levels of IgM that are markedly elevated in NZB/W F(1) mice; this appeared to be due to a prolonged effect on the ability of the splenic microenvironment to support short-lived IgM plasma cells. Finally, a short course of combination TACI-Ig and CTLA4-Ig prolonged life and even reversed proteinuria in aged NZB/W F(1) mice, suggesting that BAFF blockade may be an effective therapeutic strategy for active SLE.     

Enhanced Selection of High Affinity DNA-Reactive B Cells Following Cyclophosphamide Treatment in Mice

A major goal for the treatment of patients with systemic lupus erythematosus with cytotoxic therapies is the induction of long-term remission. There is, however, a paucity of information concerning the effects of these therapies on the reconstituting B cell repertoire. Since there is recent evidence suggesting that B cell lymphopenia might attenuate negative selection of autoreactive B cells, we elected to investigate the effects of cyclophosphamide on the selection of the re-emerging B cell repertoire in wild type mice and transgenic mice that express the H chain of an anti-DNA antibody. The reconstituting B cell repertoire in wild type mice contained an increased frequency of DNA-reactive B cells; in heavy chain transgenic mice, the reconstituting repertoire was characterized by an increased frequency of mature, high affinity DNA-reactive B cells and the mice expressed increased levels of serum anti-DNA antibodies. This coincided with a significant increase in serum levels of BAFF. Treatment of transgene-expressing mice with a BAFF blocking agent or with DNase to reduce exposure to autoantigen limited the expansion of high affinity DNA-reactive B cells during B cell reconstitution. These studies suggest that during B cell reconstitution, not only is negative selection of high affinity DNA-reactive B cells impaired by increased BAFF, but also that B cells escaping negative selection are positively selected by autoantigen. There are significant implications for therapy.     

Structure-activity relationships of some selected beta-adrenergic blocking agents--oxidation with N-bromosuccinimide.

A relationship between in vitro rate of oxidation by N-bromosuccinimide (NBS) and the pharmacologic activity (pA2) of different beta-adrenergic blockers for different blocking agent-tissue combinations has been studied. The rates of oxidation of the alcoholic group in the drugs by NBS, as well as their molecular conformations as represented by molecular models, were studied in order to determine requirements for selectivity and potency of action of beta-adrenergic blocking agents. Using data from all 7 drugs studied--both nonselective and selective blocking agents--no significant correlation between pA2 and -log k2 (k2 is the second order rate constant for the oxidative reaction) was found. If data from only the 4 nonselective agents were used (16 drug-tissue combinations), a correlation significant at p less than 0.01 was found. Hypotheses are presented to account for the selective action of some beta-adrenergic blocking agents.     

In vitro synthesis of photosynthetic membranes: I. Development of photosystem I activity and cyclic photophosphorylation

First successful $\text{in vitro}$ synthesis of functional photosynthetic phosphorylating membrane is reported. Etioplasts, highly enriched in cytoplasmic and plastid proteins, isolated from etiolated Cucumber cotyledons pretreated with kinetin and gibberellic acid, and illuminated in a cofactor fortified medium showed commencement of chlorophyll (Chl) synthesis immediately after illumination from exogenous δ-aminolevulinic acid, while photosystem I (PS I) activity commenced 15 min after the onset of illumination. When cotyledons pretreated with kinetin and gibberellic acid were illuminated directly, there was a lag phase of 30 min before the commencement of Chl synthesis and PS I activity developed after 1 h of illumination. In plastids developed both $\text{in vivo}$ and $\text{in vitro}$, the electron flow from dichlorophenolindophenol to methyl-viologen was coupled to phosphorylation as observed by an increase in the electron transport rate on the addition of uncouplers. Analysis of polypeptide profiles of the greening plastids $\text{in vitro}$ showed the disappearance of many higher molecular weight proteins during greening. Polypeptides of molecular weight 32, 20.5, 19.5 K absent in etioplasts appeared as distinct bands after 4 h of greening $\text{in vitro}$.     

PROBABLE ATTACHMENT OF THE DOLEROTHECA CAMPANULUM TO A MYELOXYLON-ALETHOPTERIS TYPE FROND

The discovery of pedunculate specimens of pollen organ Dolerotheca in close association with Myeloxylon-type pinnae and Alethopteris-type pinnules provides evidence for the reconstruction of a petrified medullosan frond and the attachment of the microsporangiate fructification. Specimens of Dolerotheca villosa and D. formosa from Middle and Upper Pennsylvanian age strata of North America are borne on slender peduncles with anatomical features and vascularization identical to those of some level in a Myeloxylon-Alethopteris-type frond. Reconstruction of the frond reveals a large, repeatedly dichotomising organ that bears penultimate pinnae and ultimate pinnules in a pinnate arrangement. Examination of pinnules on the surface of coal ball material indicates that they conform to the compression genus Alethopteris. Identical numbers and arrangement of vascular bundles together with identical anatomical features and multicellular hairs indicate that the Dolerotheca campanulum is borne in the position of a penultimate pinna. A reconstruction of the frond with a proposed polled organ attachment is included.     

Spray technique for applying stripmix (cellulose acetate) to tlc plates for tritiated organic compounds

A modification of the recent rolling technique of Redgwell, R. J., Turner, N A., and Bieleski, R. L. [(1974) J. Chromatogr.88, 25–31] for stripping thin layers from chromatographic plates for radioactive measurements has been developed. Use of this rolling technique in the case of tritiated benzo[α]pyrene and metabolites yields erratic results. By the simple expedient of spraying (instead of rolling) of the Stripmix, highly reproducible data were obtained.     

Selective deacetylation of zaluzanin D using transformed Escherichia coli cultures

The use of conventional and unconventional reaction methodology for the hydrolysis of the acetate group in zaluzanin D resulted in hydration of the 11,13 exocyclic bond along with deacetylation. But the microorganism E. coli selectively cleaved the acetate group to yield zaluzanin C.     

Pathotyping of Newcastle disease virus with a filamentous bacteriophage

A filamentous phage bearing the peptide sequence TLTTKLY was isolated from a heptapeptide phage display library against a velogenic Newcastle disease virus (NDV). In order to investigate the potential of this specific phage as an immunological reagent in virus pathotyping, an enzyme-linked immunosorbent assay (ELISA)-based method was developed. This method can differentiate the velogenic strains from the mesogenic and lentogenic strains. An equilibrium-binding assay in solution showed that the interactions between the phage and all the NDV strains gave rise to two widely differing dissociation constants (Kdrel). Based upon the first Kdrel values, NDV strains can be classified into two groups; the first comprises the velogenic strains, and the second consists of the mesogenic and lentogenic strains. These results indicate a high degree of correlation between the binding affinities and pathotyping of NDV strains using the TLTTKLY phage.