Display of functional alphabeta single-chain T-cell receptor molecules on the surface of bacteriophage

The ability to display functional T-cell receptors (TCR) on the surface of bacteriophage could have numerous applications. For instance, TCR phage-display could be used to develop new strategies for isolating TCRs with unique specificity or it could be used to carry out mutagenesis studies on TCR molecules for analyzing their structure-function. We initially selected a TCR from the murine T-cell hybridoma, DO11.10, as our model system, and genetically engineered a three domain single-chain TCR (scTCR) linked to the gene p8 protein of the Escherichia coli bacteriophage fd. Immunoblotting studies revealed that (1) E. coli produced a soluble scTCR/p8 fusion protein and (2) the fusion protein was packaged by the phage. Cellular competition assays were performed to evaluate the functionality of the TCR and showed the DO11.10 TCR-bearing phage could significantly inhibit stimulation of DO11.10 T hybridoma cells by competing for binding to immobilized MHC/peptide IA(d)/OVA(323-339). Flow cytometric analysis was carried out to evaluate direct binding of DO11.10 TCR-bearing phage onto the surface of cells displaying either IAd containing irrelevant peptide or OVA peptide. The results revealed binding of DO11.10 TCR-bearing phage only on cells expressing IA(d) loaded with OVA peptide showing TCR fine specificity for peptide. To illustrate the generality of TCR phage-display, we also cloned and displayed on phage a second TCR which recognizes a peptide fragment from human tumor suppressor protein p53 restricted by HLA-A2. These findings demonstrate functional TCR can be displayed on bacteriophage potentially leading to the development of novel applications involving TCR phage-display.     

Distribution of phosphorylated GAP-43 (neuromodulin) in growth cones directly reflects growth cone behavior

Phosphorylation of GAP-43 (neuromodulin) by protein kinase C (PKC) occurs at a single site, serine41. In vivo, phosphorylation is induced after initiation of axonogenesis and is confined to distal axons and growth cones. Within individual growth cones, phosphorylation is nonuniformly distributed. Here, we have used high-resolution video-enhanced microscopy of cultured dorsal root ganglia neurons together with immunocytochemistry with a monoclonal antibody that recognizes PKC-phosphorylated GAP-43 to correlate the distribution of phosphorylated GAP-43 with growth cone behavior. In "quiescent," nontranslocating growth cones, phosphorylated GAP-43 was confined to the proximal neurite and the central organelle-rich region, and was low in organelle-poor lamellae. However, levels in lamellae were elevated when they became motile. Conversely, levels of phosphorylated GAP-43 were low in either lamellae that were actively retracting or in the central organelle-rich region and proximal neurite of growth cones that had totally collapsed. The results suggest a mechanism whereby phosphorylation of GAP-43 by PKC, potentially in response to extracellular signals, could direct the functional behavior of the growth cone.     

Effects of hindlimb contraction on pressor and muscle interstitial metabolite responses in the cat

We used the microdialysis technique to measure the interstitial concentration of several putative metabolic stimulants of the exercise pressor reflex during 3- and 5-Hz twitch contractions in the decerebrate cat. The peak increases in heart rate and mean arterial pressure during contraction were 20 +/- 5 beats/min and 21 +/- 8 mmHg and 27 +/- 9 beats/min and 37 +/- 12 mmHg for the 3- and 5-Hz stimulation protocols, respectively. All variables returned to baseline after 10 min of recovery. Interstitial lactate rose (P < 0. 05) by 0.41 +/- 0.15 and 0.56 +/- 0.16 mM for the 3- and 5-Hz stimulation protocols, respectively, and were not statistically different from one another. Interstitial lactate levels remained above (P < 0.05) baseline during recovery in the 5-Hz group. Dialysate phosphate concentrations (corrected for shifts in probe recovery) rose with stimulation (P < 0.05) by 0.19 +/- 0.08 and 0.11 +/- 0.03 mM for the 3- and 5-Hz protocols. There were no differences between groups. The resting dialysate K+ concentrations for the 3- and 5-Hz conditions were 4.0 +/- 0.1 and 3.9 +/- 0.1 meq/l, respectively. During stimulation the dialysate K+ concentrations rose steadily for both conditions, and the increase from rest to stimulation (P < 0.05) was 0.57 +/- 0.19 and 0.81 +/- 0.06 meq/l for the 3- and 5-Hz conditions, respectively, with no differences between groups. Resting dialysate pH was 6.915 +/- 0.055 and 6.981 +/- 0.032 and rose to 7.013 (P < 0.05) and 7.053 (P < 0.05) for the 3- and 5-Hz conditions, respectively, and then became acidotic (6. 905, P < 0.05) during recovery (5 Hz only). This study represents the first time simultaneous measurements of multiple skeletal muscle interstitial metabolites and pressor responses to twitch contractions have been made in the cat. These data suggest that interstitial K+ and phosphate, but not lactate and H+, may contribute to the stimulation of thin fiber muscle afferents during contraction.     

Independent isolates of the emerging subgroup J avian leukosis virus derive from a common ancestor

A new subgroup of avian leukosis virus (ALV) that includes a unique env gene, designated J, was identified recently in England. Sequence analysis of prototype English isolate HPRS-103 revealed several other unique genetic characteristics of this strain and provided information that it arose by recombination between exogenous and endogenous virus sequences. In the past several years, ALV J type viruses (ALV-J) have been isolated from broiler breeder flocks in the United States. We were interested in determining the relationship between the U.S. and English isolates of ALV-J. Based on sequence data from two independently derived U.S. field isolates, we conclude that the U.S. and English isolates of ALV-J derive from a common ancestor and are not the result of independent recombination events.     

Value of the pretransplant evaluation in predicting toxic day-100 mortality among blood stem-cell and bone marrow transplant recipients

PURPOSE: To determine the value of pretransplant studies in predicting day 100 nonrelapse toxic mortality following high-dose therapy. PATIENTS AND METHODS: A retrospective review of 383 consecutive hematopoietic stem-cell transplants was performed with attention to toxic mortality and pretransplant factors. Univariate log-rank analysis was used to yield the most significant cut-off values for individual factors. Multivariate analysis using Cox proportional hazards regression determined factors independently predictive of early toxic death. RESULTS: Nonrelapse toxic mortality before day 100 occurred in 23 of 383 (6.0%) transplant recipients. Factors associated with an increased risk of toxic death by univariate analysis included forced expiratory volume in 1 second (FEV1) less than 78% of predicted (P = .0002), allogeneic versus autologous transplant (P = .0003), diffusion capacity of carbon monoxide less than 52% of predicted (P = .002), serum creatinine concentration greater than 1.1 mg/dL (P = .003), Eastern Cooperative Oncology Group performance status greater than 0 (P = .006), preparative regimen containing total-body irradiation versus chemotherapy alone (P = .006), marrow versus blood stem cell (P = .01), serum ALT greater than 50 IU/L (P = .02), diagnosis of hematologic disorder versus solid tumor (P = .06), serum bilirubin level greater than 1.1 mg/dL (P = .08), left ventricular ejection fraction (P = .09), and growth factor use (P = .09). In the multivariate model, transplant type (relative risk, 4.2), FEV1 (relative risk, 4.5), performance status (relative risk, 3.7), serum creatinine (relative risk, 3.8), and serum bilirubin (relative risk, 3.7) were found to be independent predictors of early toxic mortality. CONCLUSION: The pretransplant evaluation is a useful tool to identify patients at risk for early toxic mortality following high-dose therapy.     

Antitumor agents. Part 186: Synthesis and biological evaluation of demethylcolchiceinamide analogues as cytotoxic DNA topoisomerase II inhibitors

Demethylation of colchiceinamide (2) and its analogues (3-10) afforded a novel class of mammalian DNA topoisomerase II inhibitors (2a-10a) without displaying tubulin inhibitory activity. All target compounds inhibited the catalytic activity of topoisomerase II at drug concentrations at 100 microM. An in vitro cytotoxicity assay indicated that compounds 3a and 8a were strong and tissue-selective cytotoxic agents against the MCF-7 breast cancer cell line (IC50 = 0.36 and 0.48 microgram/mL, respectively) and the CAKI-1 renal cancer cell line (IC50 = 0.72 and 0.96 microgram/mL, respectively).     

Posthyperventilation apnea associated with severe hypoxemia

We studied a 14-year-old girl who suffered fractures of her mandible and tegmen following a fall from a balance beam. Thirteen days after hospitalization, she developed severe, protracted, recurrent episodes of hyperventilation; subsequently, she suffered posthyperventilation apnea, which at times was prolonged and association with severe hypoxemia with an arterial oxygen pressure as low as 25 mm Hg. The patient was treated with added dead space and chlorpromazine hydrochloride (Thorazine). Postulated mechanisms for her disorder are discussed. The importance of close clinical and laboratory observation in similar cases is stressed.