Differential signaling through the Ig-α and Ig-β components of the B cell antigen receptor

The B cell antigen receptor is a complex containing the antigen-binding immunoglobulin molecules and the Ig-α/Ig-β heterodimer which presumably connects the B cell antigen receptor to intracellular signaling components. To analyze the functional properties of the cytoplasmic parts of the B cell antigen receptor, we used the K46 B lymphoma line (IgG2a, χ) to express chimeric molecules composed of the extracellular and transmembrane part of the CD8α molecule and the cytoplasmic sequence of either the Ig-α (CD8α/Ig-α), the Ig-β (CD8α/Ig-β) protein or the membrane-bound γ2a heavy chain (CD8α/γ2a). From these three types of chimeric molecules only CD8α/Ig-α and CD8α/Ig-β, but not CD8α/γ2a, could transduce signals, thus providing the first evidence that the cytoplasmic tail of Ig-α and Ig-β have a signaling capacity. After cross-linking with anti-CD8α antibodies, both molecules induced a similar increase in intracellular free calcium ion and in MAP kinase phosphorylation. Protein tyrosine kinases, however, were strongly activated via the CD8α/Ig-α and only marginally via the CD8α/Ig-β molecule. This suggests that the Ig-α and Ig-β proteins have distinct roles during signal transduction through the B cell antigen receptor.     

Regulation of protein phosphorylation in astrocyte cultures by external calcium ions: specific effects on the phosphorylation of glial fibrillary acidic protein (GFAP), vimentin and heat shock protein 27 (HSP27)

The effect of external Ca2+ ([Ca2+]e) on the incorporation of [32P] into total protein, cytoskeletal proteins and the heat shock protein HSP27, was studied in primary cultures of astrocytes from the rat hippocampus. Zero [Ca2+]e increased total 32P-incorporation into astrocyte protein and when this was normalized to 100%, incorporation was significantly increased into glial fibrillary acidic protein (GFAP), vimentin (VIM) and HSP27. The difference in total 32P-incorporation between zero [Ca2+]e and 1 mM [Ca2+]e was reversed by incubation of the cells with the protein phosphatase inhibitor okadaic acid in the range 1-10 nM; higher concentrations of okadaic acid (50-100 nM) further increased total 32P-incorporation. In zero [Ca2+]e the non-specific channel blocker Co2+ (1 mM) decreased total 32P-incorporation by approximately 30%. The results were compared with a previous study [S.T. Wofchuk, R. Rodnight, Age-dependent changes in the regulation by external calcium ions of the phosphorylation of glial fibrillary acidic protein in slices of rat hippocampus, Dev. Brain Res. 85 (1995) 181-186] in which it was shown that in immature hippocampal slices zero [Ca2+]e compared with 1 mM [Ca2+]e increased 32P-incorporation into GFAP without changing total incorporation. The difference between the results for total 32P-incorporation obtained in cultured astrocytes and immature brain tissue was found to be related to the concentration of [Ca2+]e in the medium since in slices concentrations of [Ca2+]e higher than 1 mM progressively decreased total incorporation. The difference may reflect a higher Ca2+-permeability of the plasma membrane in cultured astrocytes and/or to the complex structure of the slice tissue. In two-dimensional electrophoresis HSP27, in contrast to GFAP and VIM, was separated into 3 immunodetectable isoforms only two of which were normally phosphorylated. After labelling in the presence of okadaic acid both immunodetectable and phosphorylated HSP27 focussed as a single polypeptide. Phorbol dibutyrate (1 microM) and zero [Ca2+]e stimulated the phosphorylation of both isoforms, but in the case of zero [Ca2+]e the effect on the more acidic isoform was proportionally greater.     

Prediction of prostatic cancer progression after radical prostatectomy using artificial neural networks: a feasibility study.

OBJECTIVE: To report a methodological feasibility study in a small series of patients with node-negative organ-confined prostatic cancer, using artificial neural networks to predict tumour progression after radical prostatectomy and thus help to identify high-risk patients who would benefit from adjuvant treatment. PATIENTS AND METHODS: A group of 20 patients with pT2N0 prostatic cancer and postoperative tumour progression was compared with a control group of 20 patients with no progression, matched for age, duration of follow-up and preoperative serum prostate-specific antigen level. Histopathological data were obtained from the radical prostatectomy specimens, i.e. the Gleason score, World Health Organisation (WHO) grade and maximum diameter of the tumour transects. The volume and surface area of the epithelial tumour component and of the lumina of the neoplastic glands per unit tissue volume were estimated by morphometric methods. To predict recurrence, multilayer feedforward networks with backpropagation (MLFF-BP), two implementations of learning vector quantization (LVQ), and linear discriminant analysis (LDA) were applied. The ability of these models to correctly classify new cases was tested using the 'leave-one-out' technique. RESULTS: Progression was predicted correctly in 85% of newly presented cases from the three routine histopathological variables alone. On the basis of the four morphometric variables alone progression was predicted correctly in 93% of cases. The use of all seven variables as input data only slightly improved the quality of prediction. The best results were obtained by the LVQ networks and LDA, followed by MLFF-BP networks. CONCLUSIONS: In this methodological feasibility study, the progression of pT2N0 prostatic cancer after radical prostatectomy could be predicted with good accuracy, sensitivity and specificity from routine variables or morphometric texture variables using artificial neural networks. These results suggest that this approach should be assessed in a prospective study with more cases.     

Artifacts in spine magnetic resonance imaging due to different intervertebral test spacers: an in vitro evaluation of magnesium versus titanium and carbon-fiber-reinforced polymers as biomaterials

Introduction  Intervertebral spacers are made of different materials, which can affect the postfusion magnetic imaging (MRI) scans. Susceptibility artifacts especially for metallic implants can decrease the image quality. This study aimed to determine whether magnesium as a lightweight and biocompatible metal is suitable as a biomaterial for spinal implants based on its MRI artifacting behavior. Materials and methods  To compare artifacting behaviors, we implanted into one porcine cadaveric spine different test spacers made of magnesium, titanium, and carbon-fiber-reinforced polymers (CFRP). All test spacers were scanned using two T1-TSE MRI sequences. The artifact dimensions were traced on all scans and statistically analyzed. Results  The total artifact volume and median artifact area of the titanium spacers were statistically significantly larger than magnesium spacers (p < 0.001), while magnesium and CFRP spacers produced almost identical artifacting behaviors (p > 0.05). Conclusion  Our results suggest that spinal implants made with magnesium alloys will behave more like CFRP devices in MRI scans. Given its osseoconductive potential as a metal, implant alloys made with magnesium would combine the advantages to the two principal spacer materials currently used but without their limitations, at least in terms of MRI artifacting.     

Prevalence and frequency of circulating t(14;18)‐MBR translocation carrying cells in healthy individuals

The t(14;18) translocation is a common genetic aberration that can be seen as an early step in pathogenesis of follicular lymphoma (FL). The significance of low level circulating t(14;18)‐positive cells in healthy individuals as clonal lymphoma precursors or indicators of risk is still unclear. We determined the age dependent prevalence and frequency of BCL2/IgH rearrangements in 715 healthy individuals ranging from newborns to octo‐ and nonagenarians. These results were compared with number of circulating t(14;18)‐positive cells in 108 FL patients at initial presentation. The overall prevalence of BCL2/IgH junctions in this large sample was 46% (327/715). However, there was a striking dependence upon age. Specifically, among individuals up to 10 years old, none had detectable circulating t(14;18)‐positive cells. In the age groups representing 10–50 years old, we found a steady elevation in the prevalence of BCL2/IgH junctions up to a prevalence of 66%. Further increases of the prevalence in individuals older than 50 years were not seen. The mean frequency of BCL2/IgH junctions in healthy individuals ≥40 years (18–26 × 10^?6) was significantly higher than in younger subjects (7–9 × 10^?6). Four percent (31/715) of individuals carried more than one t(14;18)‐positive cell per 25,000 peripheral blood mononuclear cells (PBMNCs). In comparison, 108 stage III/IV FL patients had a median number of circulating t(14;18)‐positive malignant FL cells of about 9200/1 million PBMNCs (range 7–1,000,000). These findings will further improve the understanding of the relevance of t(14;18)‐positive cells in healthy individuals as a risk marker toward the development into lymphoma precursors. © 2008 Wiley‐Liss, Inc.     

Phase III comparative study of high-dose cisplatin versus a combination of paclitaxel and cisplatin in patients with advanced non-small-cell lung cancer.

PURPOSE: New effective chemotherapy is needed to improve the outcome of patients with advanced non-small-cell lung cancer (NSCLC). Paclitaxel administered as a single agent or in combination with cisplatin has been shown to be a potentially new useful agent for the treatment of NSCLC. PATIENTS AND METHODS: Between January 1995 and April 1996, 414 patients with stage IIIB or IV NSCLC were randomized to received either a control arm of high-dose cisplatin (100 mg/m(2)) or a combination of paclitaxel (175 mg/m(2), 3-hour infusion) and cisplatin (80 mg/m(2)) every 21 days. RESULTS: Compared with the cisplatin-only arm, there was a 9% improvement (95% confidence interval, 0% to 19%) in overall response rate for the paclitaxel/cisplatin arm (17% v 26%, respectively; P=.028). Median time to progression was 2.7 and 4.1 months in the control and paclitaxel/cisplatin arm, respectively (P=.026). The study, however, failed to show a significant improvement in median survival for the paclitaxel/cisplatin arm (8.6 months in the control arm v 8.1 months in the paclitaxel/cisplatin arm, P=.862). There was more hematotoxicity, peripheral neuropathy, and arthralgia/myalgia on the paclitaxel/cisplatin arm, whereas the high-dose cisplatin arm produced more ototoxicity, nausea, vomiting, and nephrotoxicity. Quality of life (QOL) was similar overall between the two arms. CONCLUSION: This large randomized phase III trial failed to show a significant improvement in survival for the paclitaxel/cisplatin combination compared with high-dose cisplatin in patients with advanced NSCLC. However, the paclitaxel/cisplatin combination did produce a better clinical response, resulting in an increased time to progression while providing a similar QOL.     

ALK Inhibitors or Chemotherapy for Third Line in ALK-positive NSCLC? Real-world Data

ObjectivesALK inhibitors (ALKi) are the standard-of-care treatment for metastatic ALK-rearranged non-small cell lung cancer (NSCLC) in the first- and second-line setting. We conducted a real-world multi-institutional analysis, aiming to compare the efficacy of third-line ALKi versus chemotherapy in these patients.MethodsConsecutive ALK-positive metastatic NSCLC patients treated with at least one ALKi were identified in the working databases of 7 Israeli oncology centers (the full cohort). Demographic and clinical data were collected. Patients receiving any systemic treatment beyond 2 ALKi comprised the third-line cohort, whether a third ALKi (group A) or chemotherapy (group B). Groups A and B were compared in terms of overall survival (OS) and time-to-next-treatment line (TNT).ResultsAt a median follow-up of 41 months (95% confidence interval [CI]: 32-55), 80 (47.1%) have died. Median OS (mOS) in the full cohort (n = 170) was 52 months (95% CI: 32-65). Number of ALKi (hazard ratio [HR] 0.765; 95% CI: 0.61-0.95; P = .024) and age (HR 1.02, 95% CI: 1.01-1.04, P = .009) significantly associated with OS in the full cohort. The third-line cohort included 40 patients, of which 27 were treated with third ALKi (group A) and 13 treated with chemotherapy (group B). mOS from third-line initiation was 27 months in group A (95% CI: 13-NR) and 13 months for group B (95% CI: 3-NR); the difference was not significant (NS; P = .12). Chemotherapy as first line (HR 0.17, 95% CI: 0.05-0.52, P = .002) and a higher number of ALKi (HR 0.38, 95% CI: 0.20-0.86, P = .011) associated significantly with longer OS of the third-line cohort. TNT was 10 months for group A (95% CI: 5-19) and 3 months for group B (95% CI: 0-NR); the difference was NS (P = .079).ConclusionWe report mature real-world data of more than 4-year mOS in ALK-positive patients. The number of ALKi given was associated with a better outcome. OS and TNT demonstrated a statistically nonsignificant trend for a better outcome in patients receiving a third-line ALKi.     

Identification of HLA-B27-restricted cytotoxic T lymphocyte epitope from carcinoembryonic antigen.

Characterization of epitopes recognized by cytotoxic T lymphocytes (CTLs) in the sequence of tumor antigens is an important step in the development of tumor therapies. Because carcinoembryonic antigen (CEA) is a protein expressed in a high number of epithelial tumors, it is an interesting target to study. We screened for the presence of HLA-B27-restricted CTL epitopes from CEA by studying the binding to HLA-B27 of 31 synthetic peptides predicted to bind to this molecule. This afforded 16 peptides with moderate or high binding affinity. Immunization of HLA-B27 transgenic mice with the best binder peptides yielded 4 immunogenic peptides: CEA(9-17), CEA(9-18), CEA(138-146) and CEA(360-369). However, splenocytes from mice immunized with a vaccinia virus-expressing CEA recognized only CEA(9-18). These CTLs were of the CD8(+) phenotype, which upon stimulation with peptide specifically produced IFN-gamma. Moreover, they did not cross-react against peptides of region 9-18 from proteins of the CEA family. Our results show that CEA(9-18) may induce specific CTL responses against CEA.