Androgen-dependent protein interactions within an intron 1 regulatory region of the 20-kDa protein gene

The 20-kDa protein gene is androgen regulated in rat ventral prostate. Intron 1 contains a 130-base pair complex response element (D2) that binds androgen (AR) and glucocorticoid receptor (GR) but transactivates only with AR in transient cotransfection assays in CV1 cells using the reporter vector D2-tkCAT. To better understand the function of this androgen-responsive unit, nuclear protein interactions with D2 were analyzed by DNase I footprinting in ventral prostate nuclei of intact or castrated rats and in vitro with ventral prostate nuclear protein extracts from intact, castrated, and testosterone-treated castrated rats. Multiple androgen-dependent protected regions and hypersensitive sites were identified in the D2 region with both methods. Mobility shift assays with 32P-labeled oligonucleotides spanning D2 revealed specific interactions with ventral prostate nuclear proteins. Four of the D2-protein complexes decreased in intensity within 24 h of castration. UV cross-linking of the androgen-dependent DNA binding proteins identified protein complexes of approximately 140 and 55 kDa. The results demonstrate androgen-dependent nuclear protein-DNA interactions within the complex androgen response element D2.     

Amifostine protects normal tissues from paclitaxel toxicity while cytotoxicity against tumour cells is maintained

The objectives of this study were to evaluate the protective effects of amifostine against paclitaxel-induced toxicity to normal and malignant human tissues. Haematopoietic progenitor colony assays were used to establish the number of CFU-GEMM and BFU-E colonies after incubation with WR-1065 alone, Amifostine alone, paclitaxel (2.5 or 5 microM) +/- WR-1065 or amifostine. MTT and alkaline elution assays evaluated the in vitro growth inhibitory and DNA damaging effects, respectively, of paclitaxel with or without amifostine against normal human fibroblasts and human non-small cell lung cancer (NSCLC) cells. This combination was also evaluated in vivo using severe combined immune deficient (scid) mouse models of early (non-palpable tumours) and advanced (palpable tumours) human ovarian cancer. Human 2780 ovarian cancer cells were inoculated subcutaneously while paclitaxel and amifostine were administered intraperitoneally. A brief exposure (15 min) to amifostine not only protected human haematopoietic progenitor colonies from paclitaxel toxicity, but stimulated the growth of CFU-GEMM and BFU-E beyond control values. Amifostine protected normal human lung fibroblasts from paclitaxel-induced cytotoxicity and DNA single-strand breaks. However, paclitaxel cytotoxicity and DNA single-strand breaks were actually enhanced by pretreatment with amifostine in the NSCLC model. Importantly, amifostine did not interfere with paclitaxel antitumour activity even with prolonged exposure (24.5 h) of the lung cancer cells to high concentrations (1.2 mM) in vitro or following five repetitive high doses (200 mg/kg) given to scid mice with human ovarian cancer xenografts. Indeed, under certain circumstances, amifostine resulted in sensitisation of tumour cells to paclitaxel. Our results confirm previous reports of the ability of amifostine to protect normal tissues from the toxic effects of chemotherapy drugs and now extend these observations to paclitaxel.     

Effects of veratridine on the action potentials and contractility of right and left ventricles from normo- and hypertensive rats

Induction of nitric oxide synthase and generation of nitric oxide in pancreatic islet beta-cells may mediate cytokine-induced dysfunction leading to insulin-dependent diabetes mellitus. Nitric oxide generation can be regulated by availability of arginine substrate which, in turn, may be affected by substrate utilization in competing pathways such as the arginase-catalysed formation of ornithine and urea. In this study we have investigated the activity of arginase in the rat insulinoma-derived cell line RINm5F and the effect on this of interleukin 1beta, the nitric oxide synthase reaction intermediate NG-hydroxy-l-arginine and the nitric oxide-generating compounds 3-morpholinosydnonimine and S-nitrosoglutathione. Cytosols from RINm5F cells treated with or without interleukin 1beta (0.1nM, 18h) were incubated (45min, 37 degrees C) with [U-14C]arginine. Radiolabelled products ([14C]citrulline from nitric oxide synthase, [14C]ornithine and [14C]urea from arginase) were separated by high-performance liquid chromatography or ion-exchange chromatography. Interleukin 1beta increased citrulline production (from 0.01+/-0.002 to 0.58+/-0.03 pmol/microg cell protein), indicating induction of nitric oxide synthase, and significantly decreased production of both ornithine (from 4.60+/-0.20 to 3.40+/-0.20 pmol/microg) and urea (0.93+/-0.05 to 0.69+/-0.04 pmol/microg) (P<0.001), indicating decreased activity of arginase. Arginase was significantly inhibited by NG-hydroxy-l-arginine (IC50=50 microM), S-nitrosoglutathione (500 microM: 69+/-7% of control) and 3-morpholinosydnonimine (1 mM: 57+/-7% of control) (P<0.05). We conclude that during cytokine-directed beta-cell assault nitric oxide synthase-catalysed production of NG-hydroxy-l-arginine and nitric oxide may inhibit arginase thereby increasing the availability of arginine for nitric oxide production.     

Dietary guidelines for Americans: an historical perspective

The laminin peptide fragments GYIGSR-NH2 and CDPGYIGSR-NH2 are known to bind to a 67-kDa laminin receptor. This receptors is understood to be expressed at higher than normal levels in malignant tumor cells, particularly those of breast and colon carcinomas. Peptides DTPA-GYIGSR-NH2 (1), DTPA-(GYIGSR-NH2)2 (2), DTPA-CDPGYIGSR-NH2 (3), DTPA-(CDPGYIGSR-NH2)2 (4), and negative control DTPA-GAGAGA-NH2 (5) were prepared by solid-phase peptide synthesis. All five DTPA-conjugated peptides were subsequently radiolabeled with 111In and their tissue distribution evaluated in mice bearing C3H tumors. 111In-3 and 111In-4 showed the highest specific tumor localization. These preliminary data support further study of radiolabeled petide fragments for the potential detection of malignant tumors of the breast and other organs.     

Sequential statistical design strategy in an experimental kinetic study

The value of using a sequential statistical design strategy is illustrated through its use in an experimental kinetic study of the oxidation of o-xylene over a vanadium oxide catalyst. The rate of oxidation of o-xylene was determined in a differential reactor over the following ranges of conditions: 270 to 300°C, (0.5 to 3.5) x 10^-4 g.mole o-xylene/1., (1.0 to 10.0) x 10^-3 g.mole oxygen/1. The statistical design strategy for precise parameter estimation was found to be effective in increasing the precision of the parameter estimates, in reducing the correlation between parameter estimates and in showing the magnitude of this problem, and in providing a reliable prediction of the value of carrying out additional runs.     

Anisotropy of point defect diffusion in alpha-zirconium

Two types of intrinsic defect, i.e., vacancy and self-interstitial atom (SIA), are formed in metals during irradiation with energetic particles. The evolution of defect population leads to significant changes in microstructure and causes a number of radiation-induced property changes. Some phenomena, such as radiation growth of anisotropic materials, are due to anisotropy in the atomic mass transport by point defects. Detailed information on atomic-scale mechanisms is, therefore, necessary to understand such phenomena. In this article, we present results of a computer simulation study of mass transport via point defects in alpha-zirconium. The matrix of self-diffusion coefficients and activation energies for vacancy and SIA defects have been obtained, and different methods of treatment of diffusion have been tested. Molecular dynamics (MD) shows that vacancy diffusion is approximately isotropic in the temperature range studied (1050 to 1650 K), although some preference for basalplane diffusion was observed at the lower end of the range. The mechanism of interstitial diffusion changes from one-dimensional (1-D) in a 〈11 0〉 direction at low temperature (<300 K) to two-dimensional (2-D) in the basal plane and, then, three-dimensional (3-D) at higher temperatures. This article is based on a presentation made in the symposium entitled “Defect Properties and Mechanical Behavior of HCP Metals and Alloys” at the TMS Annual Meeting, February 11–15, 2001, in New Orleans, Louisiana, under the auspices of the following ASM committees: Materials Science Critical Technology Sector, Structural Materials Division, Electronic, Magnetic & Photonic Materials Division, Chemistry & Physics of Materials Committee, Joint Nuclear Materials Committee, and Titanium Committee.     

Anisotropy of point defect diffusion in alpha-zirconium

Two types of intrinsic defect, i.e., vacancy and self-interstitial atom (SIA), are formed in metals during irradiation with energetic particles. The evolution of defect population leads to significant changes in microstructure and causes a number of radiation-induced property changes. Some phenomena, such as radiation growth of anisotropic materials, are due to anisotropy in the atomic mass transport by point defects. Detailed information on atomic-scale mechanisms is, therefore, necessary to understand such phenomena. In this article, we present results of a computer simulation study of mass transport via point defects in alpha-zirconium. The matrix of self-diffusion coefficients and activation energies for vacancy and SIA defects have been obtained, and different methods of treatment of diffusion have been tested. Molecular dynamics (MD) shows that vacancy diffusion is approximately isotropic in the temperature range studied (1050 to 1650 K), although some preference for basal-plane diffusion was observed at the lower end of the range. The mechanism of interstitial diffusion changes from one-dimensional (1-D) in a direction at low temperature (<300 K) to two-dimensional (2-D) in the basal plane and, then, three-dimensional (3-D) at higher temperatures. This article is based on a presentation made in the symposium entitled “Defect Properties and Mechanical Behavior of HCP Metals and Alloys” at the TMS Annual Meeting, February 11–15, 2001, in New Orleans, Louisiana, under the auspices of the following ASM committees: Materials Science Critical Technology Sector, Structural Materials Division, Electronic, Magnetic & Photonic Materials Division, Chemistry & Physics of Materials Committee, Joint Nuclear Materials Committee, and Titanium Committee.     

Comparison of systematic search and database methods for constructing segments of protein structure

Two principal methods of determining the conformation of shortpieces of polypeptide backbone in proteins have been developed:using a database of known structures and systematicallygeneratingall conformations. In this paper, we compare the effectivenessof these two techniques. The completeness of the database forsegments of different lengths is examined and it is found tocontain most conformations for segments seven residues long,but to deteriorate rapidly for longer regions. When the databasesegment is to be incorporated into the rest of a structure,at least seven residues are required to build four new residues,because of the need to positionthe segment relative to the restof the structure.It is found that such positioning using flankingresidues results in large errors in the inserted region. Weconclude that the database method is currently not effectivefor comparative modeling, even for short segments. The systematicsearchprocedure is found to generate almost all structures of shortsegments found in proteinsIn contrast to the database method,low root mean square error structures are obtained for a setof trial segments embedded in the rest of a protein structure.Thus, it should be considered the method of choice.