cAMP response element-binding protein monomers cooperatively assemble to form dimers on DNA

We have analyzed the properties of cAMP response element-binding protein (CREB) in solution with emphasis on dimerization and effects of phosphorylation. Using a purified CREB fusion protein, a novel dye-label technique, and sedimentation equilibrium analysis, we directly and conclusively demonstrate that, unlike Jun and Fos, CREB dimerization is DNA-dependent. CREB exists primarily as a monomer in solution and cooperatively assembles on DNA to form dimers. Sedimentation equilibrium analysis also indicates that dimerization is unaffected by cAMP-dependent protein kinase-phosphorylation or by the symmetry of the cAMP-responsive element binding site. Filter binding assays reveal that CREB binding is unaffected by phosphorylation regardless of the symmetry of the cAMP-responsive element binding site. Our results suggest that structurally similar members of the same bZIP superfamily may differ significantly in their regulation at the level of dimerization.     

Selection and use of ligands for receptor-mediated gene delivery to myogenic cells

Identification of myogenic cell targeting ligands is a critical step in the development of synthetic vectors for gene delivery to skeletal muscle. Here we describe the screening of six potential targeting ligands (insulin, insulin-like growth factor I, iron transferrin, gallium transferrin, alpha-bungarotoxin and carnitine) for their ability to bind dystrophin-deficient myotubes in vitro. Those ligands showing high levels of binding to myotubes were then tested on fully differentiated, isolated, viable myofibers. Of the ligands tested, transferrin showed the most promise based on high levels of binding to myogenic cells, high levels of receptor observed in regenerating fibers of patients with Duchenne muscular dystrophy and the ability to direct a large enzyme conjugate to the cytoplasm of myotubes. Finally, we show that incorporation of transferrin into an artificial virus consisting of poly-L-lysine-condensed DNA coated with a lipid shell (LPDII formulation) results in ligand-directed delivery of DNA to myogenic cells. This is the first report of gene transfer to myogenic cells using a ligand-directed synthetic vector. These results suggest that rational design of ligand-directed, fully synthetic, gene delivery vehicles is a viable approach to skeletal muscle vector development.     

FGF2 promotes neuronal differentiation in explant cultures of adult and embryonic mouse olfactory epithelium

Neurogenesis in the adult olfactory epithelium is highly regulated in vivo. Little is known of the molecular signals which control this process, although contact with the olfactory bulb or with astrocytes has been implicated. Explants of mouse olfactory epithelium were grown in the presence or absence of several peptide growth factors. Basic fibroblast growth factor (FGF2) stimulated differentiation of sensory neurons in adult and embryonic olfactory epithelium. Other growth factors tested were ineffective. FGF2-stimulated neurons were born in vitro and expressed neurofilament, neural cell adhesion molecule, and beta-tubulin. The cells also expressed olfactory marker protein, a marker for mature olfactory sensory neurons in vivo. These bipolar neurons did not express glial fibrillary acidic protein or low-affinity nerve growth factor receptor. These results indicate that neither astrocytes nor olfactory bulb are necessary for differentiation of olfactory sensory neurons in vitro.     

Sensitivity of human prostatic carcinoma cell lines to low dose rate radiation exposure

PURPOSE: Low dose rate radioemitters, such as 125I, 103Pd, and 89Sr, have been used both for local and systemic treatment of prostate cancer. Most normal cells exposed to ionizing radiation characteristically activate cell cycle checkpoints, resulting in cell cycle arrest at the G1/S and G2/M transition points. Cancer cells are typically quite sensitive to radiation killing late in the G2 phase of the replicative cell cycle. Furthermore, most cancer cells accumulating at the G2/M transition point as a result of low dose rate radiation exposure appear to become sensitive to further low dose rate irradiation. For this reason, protracted exposure of cancer cells to low dose rate radiation has been proposed to result in increased cancer cell killing as compared with brief exposures of cancer cells to high dose rate radiation. Since many human prostatic carcinomas contain somatic genome alterations targeting genes which affect the cell cycle and radiation-associated cell cycle checkpoints, we evaluated the effects of low dose rate radiation exposure on the cell cycle and on clonogenic survival for various human prostatic carcinoma cell lines. MATERIALS AND METHODS: Human prostatic carcinoma cells from the LNCaP, DU 145, PC-3, PPC-1, and TSU-Pr1 cell lines were exposed to low dose rate (0.25 Gy/hour) or high dose rate (60 Gy/hour) radiation in vitro and then assessed for radiation cytotoxicity by clonogenic survival assay. Cell cycle perturbations following protracted exposure to low dose rate radiation were evaluated using flow cytometry. RESULTS: For LNCaP cells, low dose rate radiation exposure resulted in an accumulation of cells at both the G1/S and the G2/M cell cycle transition points. For DU 145, PC-3, PPC-1, and TSU-Pr1 cells, treatment with low dose rate radiation triggered G2/M cell cycle arrest, but not G1/S arrest. Unexpectedly, the cell cycle redistribution pattern phenotypes observed, G1/S and G2/M cell cycle arrest versus G2/M arrest alone, appeared to have little effect on low dose rate radiation survival. Furthermore, while PC-3, PPC-1, and TSU-Pr1 cells exhibited increased cytotoxic sensitivity to low dose rate versus fractionated high dose rate radiation treatment, DU 145 and LNCaP cells did not. CONCLUSIONS: Radiation-associated pertubations in replicative cell cycle progression were not dominant determinants of low dose rate radiation killing efficacy in human prostate cancer cell lines in vitro.     

Impact on survival by method of recurrence detection in stage I and II cutaneous melanoma

Immunoaffinity columns were made with specific egg yolk immunoglobulin (Ig) Y against bovine IgG1 and IgG2 and were used to isolate pure IgG1 and IgG2 from Cheddar cheese whey or colostrum. About 10% of the IgY was specific for IgG, and 3% of the IgY was subclass-specific after hyperimmunization of laying hens with either IgG1 or IgG2. Up to 38% of the potential binding capacity of IgY was obtained after immobilization by reductive amination. The IgY columns were stable, and one column could be reused for more than 50 times for over a year with minimal loss in binding capacity. Milk that was free of either IgG subclass was successfully produced by the selective removal of IgG1 or IgG2 subclasses. Double-immunodiffusion analysis confirmed the isolation of subclasses from whey and colostrum and also confirmed that their removal from milk was specific.     

Patient-controlled versus anesthesiologist-controlled conscious sedation with propofol for dental treatment in anxious patients

In a randomized, cross-over study, we prospectively compared the efficacy and quality of two methods to achieve conscious sedation with propofol in 11 unpremedicated, anxious dental patients. Each patient underwent two dental procedures, one that was conducted under target-controlled infusion (TCI) by the anesthesiologist (ACS), and the other that used patient-controlled sedation (PCS). The initial target concentration in the ACS mode was 2.5 microg/mL, which was manipulated in both directions until the desired clinical end point was achieved. In the PCS mode, a 4-mg bolus of propofol (10 mg/mL) was delivered at each activation of the machine, infused over 7 s without a lockout interval. The anxious dental patients could induce and maintain conscious sedation with the PCS settings. The mean (range) venous blood propofol concentrations were not significantly different with either mode: ACS 1.8 (0.8-2.7) microg/mL and PCS 1.2 (0.2-2.5) microg/mL. The level of patient satisfaction, quality of sedation, and treatability were not different for either mode of sedation. The intensity of amnesia for intraoperative events was related to the blood concentrations achieved. In the ACS mode, one patient became unresponsive (sedation level 4) immediately after the start of sedation. No adverse cardiorespiratory effects resulted from either mode of propofol sedation. Five patients expressed a strong preference for PCS, and three would prefer ACS in the future. The results of the present study suggest that with these PCS settings, a satisfactory level of conscious sedation and a high level of patient satisfaction was achieved. Implications: In a randomized, cross-over study, the blood propofol concentrations necessary to achieve conscious sedation in anxious dental patients using a target-controlled infusion conducted by the anesthesiologist versus patient-controlled sedation were not different. With the patient-controlled sedation settings, a satisfactory level of conscious sedation and a high level of patient satisfaction were achieved.     

A new series of C3-aza carbocyclic influenza neuraminidase inhibitors: synthesis and inhibitory activity

The synthesis and influenza neuraminidase inhibitory activity of a new series of C3-aza carbocyclic neuraminidase inhibitors are described. Analogues 3c and 3j, bearing a 3-pentyl group, exhibit influenza A inhibitory activities comparable to that of 1.     

A new reliable laboratory test of endurance performance for road cyclists

PURPOSE: The purpose of this study was to devise and evaluate a laboratory test of cycling performance that simulates the variable power demands of competitive road racing. The test is a 100-km time trial interspersed with four 1-km and four 4-km sprints. METHODS: On three occasions separated by 5-7 d, eight endurance-trained cyclists (peak oxygen uptake 5.0 +/- 0.7 L.min-1, peak power output 411 +/- 43 W, mean +/- SD) performed the test on their own bikes mounted on an air-braked Kingcycle ergometer. Subjects were free to regulate their power output but were asked to complete each sprint and the full distance as quickly as possible. The only feedback given to the cyclists during each test was elapsed distance. RESULTS: In the first test, time for the 100 km and mean times for the 1-km and 4-km sprints were 151:42 +/- 10:36, 1:16 +/- 0:06, and 5:31 +/- 0:16 min:s, respectively; these times improved by 1.6-2.2% in the second test, but there was little further improvement in the third test (0.7 to -0.5%). The between-test correlation for 100-km time was 0.93 (95% CI 0.79 to 0.98), and the within-cyclist coefficient of variation was 1.7% (95% CI 1.1 to 2.5%). Mean sprint performance showed similar good reliability (within-subject variation and correlations for the 1-km and 4-km sprint times of 1.9%, 2.0%, 0.93, and 0.81, respectively). CONCLUSIONS: The high reliability of this laboratory test will make the test useful for research on performance of competitive road cyclists.     

Investigation methods for the detection and study of stress-relief cracking

The occurrence of grain boundary damage and stress-relief cracking within heat-affected zones of pressure vessel weldments and claddings has led to numerous investigations. The metallographic and fractographic as well as microanalytical methods used are reported in respect of the results obtained and the given limits. Within the range of microanalysis the application of the electron beam microprobe is described for the detection of micro segregations as well as companion elements and trace elements, Auger spectroscopy for the investigation of thin grain boundary films, transmission electron microscopy especially for the identification of precipitations, and the photoemission electron microscope for the analysis of transformation and precipitation behaviour, as well as the so-called phase analysis for better knowledge in the field of kinetics of phases.Using the results of these methods, which were applied on real welded joints as well as on weld simulation tests, it was possible to prove the validity of the chosen parameters for the welding simulation. Further efforts will be made to find more clear correlations between the contents of alloying elements in the base material and the precipitation or crack behaviour in the coarse grain zone of the HAZ.     

Mitochondrial mutational spectra in human cells and tissues

We have found that human organs such as colon, lung, and muscle, as well as their derived tumors, share nearly all mitochondrial hotspot point mutations. Seventeen hotspots, primarily G --> A and A --> G transitions, have been identified in the mitochondrial sequence of base pairs 10,030-10,130. Mutant fractions increase with the number of cell generations in a human B cell line, TK6, indicating that they are heritable changes. The mitochondrial point mutation rate appears to be more than two orders of magnitude higher than the nuclear point mutation rate in TK6 cells and in human tissues. The similarity of the hotspot sets in vivo and in vitro leads us to conclude that human mitochondrial point mutations in the sequence studied are primarily spontaneous in origin and arise either from DNA replication error or reactions of DNA with endogenous metabolites. The predominance of transition mutations and the high number of hotspots in this short sequence resembles spectra produced by DNA polymerases in vitro.