immune tolerance ͉ anti-A␤-antibodies ͉ lipid A ͉ A␤-fiber solubilization A lzheimer's disease (AD) is a progressive degenerative disorder of insidious onset characterized by memory loss, confusion, and a variety of cognitive disabilities. The major neuropathological change in the brains of AD patients is neuronal death, particularly in regions related to memory and cognition (1). One of the major pathological features of AD is the abundant presence of amyloid plaques in the brain of affected individuals (2). Intracellular bundles of paired helical filaments, composed largely of phosphorylated tau protein, accumulate in large amounts in dying neurons (3). On the neuron surfaces, insoluble aggregates of proteinaceous debris, termed amyloid, appear in the form of neuritic plaques and vascular amyloid deposits (1). The frequency and distribution of the neurofibrillar tangles and of the neuritic plaques appear to correlate well with the extent of cognitive impairment and other characteristic symptoms of AD (3).Amyloid plaques are formed by the ␤-amyloid peptide (A␤), a 39-to 43-aa-long polypeptide that is mostly coiled and slightly ␣-helical in its benign soluble form and, on conformational transition into a mainly ␤-sheet secondary structure, spontaneously aggregates into insoluble deposits. A␤ is a physiological metabolite of the much larger amyloid precursor protein (APP), 695-770 aa long, which undergoes sequential proteolysis (4). The peptide may remain in solution as a random coil or an ␣-helix (5).A mAb, raised against the sequence A␤ 1-16 of the amyloid protein, was shown in vitro to have a solubilizing effect on fibrils formed by the A␤ 1-42 amyloidogenic peptide (6). The amyloid filaments obtained were similar to those found in amyloid plaques and cerebrovascular amyloid, assembled from chemically synthesized amyloid sequences under defined experimental conditions (6).Previous studies in our laboratory had shown that palmitoylated peptide sequences of the multidrug-resistance (MDR)1 protein, reconstituted in the bilayer of liposomes, when injected into mice elicited strong immune responses, breaking the immune tolerance to this ''self'' protein (7).In the present study, we report that the palmytoilated A␤ 1-16 sequence reconstituted in liposomes-lipid A, when injected i.p. into mice, including transgenic NORBA mice, which overexpress human APP resulting in amyloid plaque deposits on their pancreases, elicited significant titers of antiamyloid antibodies displaying therapeutic as well as prophylactic action in NORBA transgenic mice. Materials and MethodsChemicals. Dichloromethane from Carlo Erba (Milan) was distilled freshly from calcium hydride under nitrogen before use. Acetic anhydride, 4-dimethylaminopyridine, and dicyclohexylcarbodiimide were purchased from Sigma-Aldrich; ␣,-dipalmitoyllysine was synthesized according to literature methods (8); ␣-fluorenylmethoxycarbonyl (Fmoc)--palmitoyllisine [FmocLys(Pal)OH], the 4-alkoxybenzyl alcohol resin for automated solid-phase synthesis, as well as A␤ 1-42 , ...

Adventitious root formation (ARF) was studied in woody leaf bud cuttings of Ficus pumila L., creeping fig. Juvenile cuttings rooted easily, whereas only mature cuttings treated with indole‐3‐butyric acid (IBA) attained any rooting success. In the rooting process, both juvenile and mature material exhibited dedifferentiation of phloem ray parenchyma, root initial formation, primordia differentiation, and root elongation. The early stages of adventitious rooting were most critical since few primordia were observed in mature controls. The stages leading up to root primordia differentiation and elongation occurred more rapidly in IBA‐treated juvenile vs. mature cuttings; however, time differences in both types between first observable roots and maximum rooting were comparable. Root primordia differentiated from basal callus of some cuttings, but neither these nor the few primordia in mature controls elongated into well‐developed roots. Anatomical differences between the juvenile and mature material did not account for rooting disparity, nor did presence of perivascular fibers, sclereids, and laticifers retard rooting.

Recombinant full-length CD4 expressed in Spodopterafrugiperda 9 cells with the baculovirus system was electroinserted in erythrocyte (RBC) membranes. Of the inserted CD4, 70% was "correctly" oriented as shown by fluorescence quenching experiments with fluorescein-labeled CD4. The inserted CD4 displayed the same epitopes as the naturally occurring CD4 in human T4 cells. Double-labeling experiments (12'I-CD4 and 51Cr-RBC) showed that the half-life of CD4 electroinserted in RBC membrane in rabbits was approximately 7 days. Using the fluorescence dequenching technique with octadecylrhodamine B-labeled human immunodeficiency virus (HIV)-1, we showed fusion of the HIV envelope with the plasma membrane of RBC-CD4, whereas no such fusion could be detected with RBC. The dequenching efficiency of RBC-CD4 is the same as that of CEM cells. Exposure to anti-CD4 monoclonal antibody OKT4A, which binds to the CD4 region that attaches to envelope glycoprotein gp120, caused a significant decrease in the dequenching of fluorescence. In vitro infectivity studies showed that preincubation of HIV-1 with RBC-CD4 reduced by 80-90% the appearance ofHIV antigens in target cells, the amount of viral reverse transcriptase, and the amount of p24 core antigen produced by the target cels. RBC-CD4, but not RBCs, aggregated with chronically HIV-i-infected T cells and caused formation of giant cells. These data show that the RBC-CD4 reagent is relatively long lived in circulation and efficient in attaching to HIV-1 and HIV-infected cells, and thus it may have value as a therapeutic agent against AIDS.