Studies on the types of immune responses to synthetic antigens in guinea-pigs

The immune response in guinea-pigs to linear and multichain copolymers of two, three or four different amino acids including tyrosine, glutamic acid, alanine and lysine, was studied.

Delayed-type response was favoured in the case of preparations of relatively low molecular weight, containing only tyrosine and glutamic acid in their potential antigenic specificity determinants. Delayed sensitivity to one of these preparations was passively transferred with lymphoid cells.

Antibody response resulted from the immunization of animals with preparations of relatively high molecular weight and with a more heterogeneous chemical composition. The antibody formation was intensified and accelerated, when p-azobenzenearsonate conjugates of the polypeptides were used as antigens.

Variations in the immunizing dose had little or no effect on the nature of the reactions. A response of exclusively delayed type could not be intensified by repeated immunizations. The presence of mycobacteria in the immunizing injection was essential for the elicitation of the response to multichain, but not to linear copolymers.

     

Selective accumulation of cells with 'B' properties in stimulated lymph nodes.

Draining lymph nodes from mice which had been stimulated with bacterial adjuvants or the skin sensitizing agent, oxazolone, showed a marked increase in cell content, presumably due to lymphocyte immigration. A surprisingly large proportion of these cells exhibit properties of B lymphocytes: the presence of surface Ig, lack of Thy-1-like antigen and responsiveness to lopopolysaccharide (LPS). The relationship between the presence of surface markerand responses to class-specific mitogens, of cells from the stimulated nodes, was established by testing fractionated lymphocyte populations. Enriched T cells did not react to LPS, whereas removal of cells with Thy-1 antigen by specific antisera eliminated the reactions to T mitogens but had little or no effect on the LPS response. The data thus suggest that B cells, which make up a small portion of the circulating lymphocyte pool, are selectively accumulated in lymph nodes stimulated by different immunogens, including T-specific stimulants. This interpretation contradicts the generally accepted assumption, that stimulat lymph nodes trap mostly T lymphocytes.     

Structural control of immunogenicity. II. Antibody synthesis and cellular immunity in response to immunization with mono-epsilon-oligo-L-lysines

A detailed evaluation of the capacity of mono-ε-DNP-oligo-L-lysines to initiate anti-DNP antibody synthesis and a state of delayed hypersensitivity in guinea-pigs is presented. Peptides containing as few as two lysine residues elicit the production of significant amounts of anti-DNP antibody when they are administered as Freund''s complete adjuvant emulsions. Under these immunization conditions, the serum concentration of anti-DNP antibody is dependent on the chain length of the peptide, and on the amount and kind of mycobacteria in the adjuvant; guinea-pigs lacking the PLL gene produce amounts of anti-DNP antibody indistinguishable from that produced by guinea-pigs possessing this gene. On the other hand, when guinea-pigs are immunized with either 1-ε-DNP-tetra-L-lysine or 1-ε-DNP-nona-L-lysine without the use of mycobacterial adjuvant, anti-DNP antibody is produced only by guinea-pigs receiving the nona-L-lysine and only by those animals possessing the PLL gene.Delayed hypersensitivity results from immunizing PLL+ guinea-pigs with mono-ε-DNP-octa and nona-lysines but not from immunization with mono-ε-DNP-hexa-lysine; PLL— animals do not exhibit delayed hypersensitivity to any of these compounds.The data suggest that antibody synthesis to positively charged compounds may proceed as a result of formation of charge complexes with mycobacterial proteins; under such immunization conditions the intrinsic immunogenicity of a compound is more reliably revealed by the induction or elicitation of cellular immune responses. On this basis, a definite discontinuity in the degree of immunogenicity of the mono-ε-DNP-oligo-L-lysines occurs as the peptides are lengthened from six to eight residues.     

Surface charge on polymeric implants and calcified tissues: interfacial implications

Samples of human bone, dentin, and enamel were analyzed through the technique known as thermally stimulated discharge (TSD). It is possible through this technique to detect current flow resulting from appearance or loss of net polarization in a material. Samples of freshly extracted tissue give rise to well-defined TSD current maximal without having been exposed to external electrical potentials. Calculation of activation energies for these currents and their thermal range suggests the involvement of collagen denaturation in the loss of appearance of a net surface charge on bone and dentin surfaces. In the case of enamel samples, TSD current maxima are possibly the result of dipolar alignment in water or biopolymers by surface charges in the mineral phase. Interfacial implications of surface charge were studied through the measurement of adhesive strength in dentin/acrylic polymer joints. Enhancement of joint strength by a factor of two or higher was observed when powder particles of the experimental adhesive carried externally induced surface charge. It is hypothesized that electrostatic coupling between polarization domains on the tissue surface and the setting implant improves wetting and produces stronger interfaces.     

A paradigm for single nucleotide polymorphism analysis: the case of the acetylcholinesterase gene

Acetylcholinesterase (AChE) plays a crucial physiological role in termination of impulse transmission at cholinergic synapses through rapid hydrolysis of acetylcholine. It is a highly conserved molecule, and only a few naturally occurring genetic polymorphisms have been reported in the human gene. The goal of the present study was to make a systematic effort to identify natural single nucleotide polymorphisms (SNPs) in the human ACHE gene. To this end, the genomic coding sequences for acetylcholinesterase of 96 unrelated control individuals from three distinct ethnic groups were analyzed. A total of 13 ACHE SNPs were identified, 10 of which are newly described, and five that should produce amino acid substitutions [c.101G>A (p.Arg34Gln), c.169G>A (p.Gly57Arg), c.1031A>G (p.Glu344Gly), c.1057C>A (p.His353Asn), and c.1775C>G (p.Pro592Arg)]. Population frequencies of 11 of the 13 SNPs were established in four different populations: African Americans, Ashkenazi Jews, Sephardic Jews, and Israeli Arabs; 15 haplotypes and five ethnospecific alleles were identified. The low number of SNPs identified until now in the ACHE gene is ascribed to technical hurdles arising from the high GC content and the presence of numerous repeat sequences, and does not reflect its intrinsic heterozygosity. Among the SNPs resulting in an amino acid substitution, three are within the mature protein, mapping on its external surface: they are thus unlikely to affect its catalytic properties, yet could have antigenic consequences or affect putative protein-protein interactions. Furthermore, the newly identified SNPs open the door to a study of the possible association of AChE with deleterious phenotypes-such as adverse drug responses to AChE inhibitors employed in treatment of Alzheimer patients and hypersensitivity to pesticides.     

Synthesis of a poly(L-lysine)-calcium phosphate hybrid on titanium surfaces for enhanced bioactivity

Titanium has been a successful implant material owing to its excellent strength to weight ratio, toughness, and bioinert oxide surface. Significant progress has been made on the improvement of titanium's bioactivity by coating its oxide surface with calcium phosphates and bioactive molecules. Here, we report on the coating of titanium with a poly(L-lysine)-calcium phosphate hybrid material with a nanoscale texture. This hybrid coating was grown by first nucleating seed crystals of calcium phosphate, directly on the Ti surface and then exposing this surface to solutions containing Ca(2+), PO(4)(3-), and poly(L-lysine). The resultant hybrid coating was characterized by electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and elemental analysis. This material contained 14% by weight poly(L-lysine), and this organic component decreased greatly the dimensions of the surface features, thus enhancing surface area relative to the inorganic control. The highly textured hybrid material was more susceptible than the control to acidic and enzymatic degradation. The amino acid cysteine was covalently linked to the hybrid material, demonstrating the potential of this coating for further functionalization. These hybrid coatings may prove useful in enhancing the bioactivity of titanium.     

Phase II study of first-line chemotherapy with temozolomide in recurrent oligodendroglial tumors: the European Organization for Research and Treatment of Cancer Brain Tumor Group Study 26971.

PURPOSE: Oligodendroglial tumors are chemotherapy-sensitive tumors, with two thirds of patients responding to combination chemotherapy with procarbazine, lomustine, and vincristine (PCV). Temozolomide (TMZ), a new alkylating and methylating agent, has demonstrated high response rates in patients with recurrent anaplastic astrocytoma. We investigated TMZ as first-line chemotherapy in recurrent oligodendroglial tumors (OD) and mixed oligoastrocytomas (OA) after surgery and radiation therapy. PATIENTS AND METHODS: In a prospective, nonrandomized, multicenter, phase II trial, patients were treated with 200 mg/m2 of TMZ on days 1 through 5 in 28-day cycles for 12 cycles. Patients with a recurrence after prior surgery and radiotherapy, and with measurable and enhancing disease on magnetic resonance imaging (MRI) were eligible for this study. Patients with large lesions and mass effect or with new clinical deficits were not eligible. Pathology and the MRI scans of all responding patients were centrally reviewed. RESULTS: Thirty-eight eligible patients were included. In three patients, pathology review did not confirm the presence of an OD or OA. TMZ was generally well tolerated. The most frequent side effects were hematologic; only one patient discontinued treatment for toxicity. In 20 (52.6%) of 38 patients (95% exact confidence interval, 35.8% to 69.0%), a complete (n = 10) or partial response to TMZ was observed. The median time to progression was 10.4 months for all patients and 13.2 months for responding patients. At 12 months from the start of treatment, 40% of patients were still free from progression. CONCLUSION: TMZ provides an excellent response rate with good tolerability in chemotherapy-naive patients with recurrent OD. A randomized phase III study comparing PCV with TMZ is warranted.     

Ventricular arrhythmia and torsade de pointe: Dose limiting toxicities of the MDR-modulator S9788 in a phase I trial

Background: S9788 is a triazineaminopiperidine derivative capable of reversing multidrug resistance (MDR) in vitro. In preclinical models S9788 was several fold more potent MDR inhibitor than verapamil or cyclosporine. At P-glycoprotein (Pgp) blocking concentrations, S9788 appeared to have only very little toxicity.Patients and methods: In a two step phase I trial we treated 39 patients with refractory cancer with S9788 and bolus doxorubicin. The steps differed mainly in the S9788 infusion duration; in the first part 23 patients received the MDR-reversing drug S9788 over 30 minutes, in the second step of the study 16 patients were administered S9788 over 150 minutes. The doses of S9788 were escalated in cohorts of three patients up to a dose level (DL) of 96 mg/m2 on the 30 minutes infusion, and to 144 mg/m2 on the 150 minutes infusion. The pharmacokinetics of S9788 were determined.Results: With the 30-minute infusion schedule symptomatic cardiac arrhythmia were found to be dose limiting. In all patients at the highest DL transient cardiac repolarization prolongation with a long QT-interval on ECG was demonstrated. With the 150-minute administration schedule, S9788 could be escalated up to 144 mg/m2 without subjective toxicity. However, transient QT prolongation was present in all patients. A third degree AV-block and a QT increase of about 40% occurred at the highest DL. Asymptomatic torsade de pointe (DL 96 mg/m2) was demonstrated on Holter recording in one patient. Theses repolarization disturbances with QT increase were considered dose limiting toxicity and the trial was closed. No arrhythmia related death was noted. Pharmacokinetics were similar with both infusion schedules with a mean alpha half life of 11.3 and 13.2 minutes, for the 30-minute and 150-minute infusion, and a terminal half life of 13.5 and 15 hours, respectively. QTc prolongation duration appeared to be dose-dependent.Conclusions: With the tested infusion schedules, cardiac toxicity, in particular AV-blocks and QT prolongation, leading to ventricular arrhythmia and torsade de pointe, are the dose limiting toxicities of S9788. Our experience together with the observation of asymptomatic torsade de pointe in two other phase I trials of S9788 infused over six hours precluded the further clinical development of S9788.     

Do statins,ACE inhibitors or sartans improve outcome in primary glioblastoma?

The prognosis of the association between Breast Cancer (BC) and Meningioma (M) is unknown. To evaluate the survival impact of tumor exposure sequence in patients with both tumors. Patients were divided in groups according to the tumors sequence: BC before M (group 1), synchronous BC?+?M (group 2) and BC after M (group 3). The SEER database was used. Demographics, meningioma and breast cancer variables were analyzed. The primary outcome was oncological survival. A total of 1715 patients were included (median follow-up:84 months). Group 2 had the shortest survival (median:32 months) and group 1 the longest (median:110 months). On the unadjusted analysis, group 2 had the shortest survival (HR:3.13, 95% CI 1.62–6.04) and adjusted analysis confirmed this finding (HR 3.11, 95% CI 1.58–6.19), with no statistical difference between the metachronous tumors groups. Increasing age (HR:1.13, 95% CI 1.11–1.15, p?<?0.005) and grade III meningioma (HR:4.51, 95% CI 1.90–10.69, p?<?0.005) were related with lower survival. Meningioma treatment had no influence on the survival (p?>?0.05). The association between surgery and radiotherapy in BC treatment improved the outcome (HR 0.37, 95% CI 0.23–0.93, p?<?0.05). Grade III meningioma and receptor hormonal status influenced synchronous tumors (p?<?0.05) but had no influence on metachronous tumors survival (p?>?0.05) on stratified analysis. Synchronous tumors were associated with lower survival. Increasing age had a negative influence on patient survival. Although surgery and radiotherapy for breast cancer had a positive influence in the outcome, meningioma treatment was not related with survival. Grade III meningioma and hormonal receptor status only influenced synchronous tumors patient survival.