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Results for “Phosphorus Isotopes”

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At least 19 recordsLinked to original sources
PubMed1990

Biotin and phosphorus-isotopic labelled DNA/RNA probes for the detection of human papilloma virus sequences.

In this study, the diagnostic accuracy and practicability of different hybridization techniques for the detection of human papilloma virus (HPV) DNA were tested. Cervical cell scrapes (n = 67) were analysed for HPV-DNAs 6/11 and 16, in order to compare a commercially available in situ DNA hybridization-assay with the conventional Southern-blot analysis. The in situ DNA hybridization-assay gave a sensitivity of 81.5%, a specificity of 97.5% and a diagnostic efficiency of 91.0% for HPV-DNAs 6/11. Using the same assay, we observed a sensitivity of 100%, a specificity of 96.3% and a diagnostic efficiency of 97.0% for HPV-DNA 16. The practicability of dot-blot DNA hybridization technique was tested on 176 cervical cell scrapes, in order to determine the prevalence rate of HPV-genotypes 6/11, 16/18 and 31/33/35. In the random control group (n = 106), 1.9% of the cases were HPV-DNA positive. In the cancer prevention group (n = 70), patients with reactive and reparative cell changes showed a HPV-DNA positivity of 55.0%, with mild (slight) dysplasia/CIN 1 of 73.7%, and with moderate to severe dysplasia/CIN 2 to CIN 3, including the carcinoma in situ/CIN 3 of 80.0%. Patients with squamous cell carcinoma of the cervix uteri gave HPV-DNA positive results in 96.2% of the cases. The suitability of in situ DNA hybridization for morphological studies was tested on tissue biopsies (n = 68). The HPV-DNAs 6/11 were found predominantly to 72.7% of the examined condylomas. The HPV-DNA positive cervices increased with the severity of the cytological dysplasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Biotin↗
PubMed1977

The specificity of S1 nuclease toward RNA-DNA hybrids as studied using isotopes of phosphorus-32 and phosphorus-33.

Hybrids were formed from Bacillus cereus DNA and ribosomal RNA. They were treated with various combination of S1 nuclease and ribonuclease, and the molar ratios of the RNA and DNA moieties remaining in the treated hybrids were determined using a 32P-33P dual-label technique. It was found that both S1 nuclease and ribonuclease are required to give hybrid with RNA and DNA in a perfect 1:1 molar ratio. It was noted that the dual-label technique which employs orthophosphate as the sole phosphorus source for both labels gives unambiguous molar ratios and obviates the need to calculate specific activities, make quench corrections, or correct for base content.

Bacillus cereus↗
PubMed1969

Identification of components of (Na+ plus K+)-adenosine triphosphatase by double isotopic labeling and electrophoresis.

A microsomal adenosine triphosphatase (ATPase) that requires both sodium and potassium ions is thought to be identical with, or an integral part of, the active cation transport system located in cell membranes. Attempts to isolate and purify (Na(+) + K(+))-ATPase have met with limited success because solubilization of microsomal protein causes partial, if not complete, loss of enzymatic activity. We now report the isolation from rat kidney microsomes of proteins which, though enzymatically inactive, could still be identified as components of the (Na(+) + K(+))-ATPase system. Phosphoproteins known to be intermediates in the hydrolysis of ATP by (Na(+) + K(+))-ATPase were prepared by incubating rat kidney microsomes with gamma-labeled ATP(33) in the presence of sodium or with P(32)-orthophosphate in the presence of ouabain. After the P(32)- and P(33)-labeled microsomes had been dissolved in phenol-acetic acid-urea, the resultant solutions were mixed and subjected to polyacrylamide gel electrophoresis. The radioactivity from both phosphorus isotopes was found almost exclusively in one of the resultant 21 protein bands. In contrast, the radioactive protein from DFP(32)-labeled microsomes moved slightly faster than the radioactive protein from microsomes labeled with P(33)-orthophosphate in the presence of ouabain. DFP inhibits (Na(+) + K(+))-ATPase by reacting with a nucleophilic site at or near the active site. These results suggest that while a single protein component of (Na(+) + K(+))-ATPase accepts the terminal phosphate from ATP, the final splitting of this phosphoprotein intermediate may be catalyzed by nucleophilic sites on a second protein.

Adenosine Triphosphatases↗
PubMed1996

Dosimetry of radionuclide therapy using radiophosphonated antisense oligodeoxynucleotide phosphorothioates based on animal pharmacokinetic and tissue distribution data.

The aim of this study was to evaluate the therapeutic possibilities of radiolabeled antisense oligodeoxynucleotides. The internal radiation dose from known cellular and animal data was calculated, and the suitability of different phosphorus isotopes as labels for oligonucleotides was assessed. We calculated the pharmacokinetics and tissue distribution in vivo of short oligodeoxynucleotide phosphorothioates by using the data from two different radionuclides: phosphorus-33 (t1/2 = 24.4 days, maximum beta-energy = 250 ke V) and phosphorus-32 (t1/2 = 14.3 days, maximum beta-energy = 2270 ke V). The absorbed doses of 32P-labeled and 33P-labeled oligonucleotides were estimated using the published biodistribution data for several oligonucleotides in animal models for both tumor xenografts and AIDS. The local absorption of 33P was higher than that of 32P if the radius of the spherical distribution of activity was smaller than approximately 500 microns. In a mouse tumor xenograft model, an intravenously injected activity of 1 MBq achieved sufficient radiation doses in the tumor; 11 Gy for 32P and 1.5 Gy for 33P were obtained. In normal organs in the same model, the liver doses were 5.0 Gy (32P) and 0.7 Gy (33P), and the kidney doses were 14 Gy (32P) and 2.0 Gy (33P). We conclude that 33P may have more beneficial radiotherapeutic characteristics for oligonucleotides than 32P. This method could be applied on the macroscopic, cellular, and subcellular levels and help to design further experimental studies for the use of oligonucleotide radiotherapy and phosphorothioate probes.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Determination of specific protein kinase activities using phosphorus-33.

The immune complex kinase assay is the most widely applied method to assess the catalytic activity of protein tyrosine kinases. It offers the advantage that the activity of a single selected enzyme can be determined, and that the enzyme activity can be normalized for the amount of enzyme in a parallel immunoblotting experiment. Here, we describe the use of the recently introduced isotope phosphorus-33 for the protein kinase assay. The lower energy of 33P, compared with the traditionally applied 32P, allows the simultaneous examination of the amount of enzyme with 125I-labeled antibodies. By analysing one and the same sample for both kinase activity and protein amount, the variation between parallel processed samples is avoided. Using this method, specific kinase activities can be calculated with high precision. The assay is particularly useful for the detection of cytokine and growth factor-induced activation of kinases, as changes in enzyme amounts by subcellular relocalization can be distinguished.

Carcinoma↗
PubMed1970

Radioactive drugs.

Explore the source record for details and available documents.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

Quantitation of metabolites in NMR spectra from isolated tissues, using 14N spectroscopy and nitrate to determine tissue volume.

Quantification of metabolites is a goal of many biomedical NMR studies. To obtain absolute measurements of metabolite concentrations is often both difficult and time-consuming. In this paper a method for determining metabolite concentrations directly is described and validated. It is applicable to studies of amphibian muscles, and with suitable precautions, to other isolated organs and tissues. The method is based upon using 14N NMR and nitrate-containing solutions to determine what fraction (F) of the sensitive volume of the RF coil is occupied by tissue. As the concentration of nitrate is known it can be used to calibrate other 14N metabolites in the tissue. Moreover, once F is determined, it can be used to calibrate metabolites in spectra from other nuclei e.g., 31P or 31C. All that is required is that a spectrum from a standard for that nucleus is obtained. Thus this method does not require any 'internal' (intrinsic to the tissue) standard, and is extremely quick and simple to use.

Adenosine Triphosphate↗
PubMed1993

An efficient procedure for assignment of the proton, carbon and nitrogen resonances in 13C/15N labeled nucleic acids.

An efficient method is presented for the assignment of the proton, carbon, and nitrogen resonances in the NMR spectra of isotopically labeled nucleic acids. The assignment strategy starts by identifying all protons and carbons belonging to the same sugar ring through application of a set of 2D or 3D heteronuclear HCCH NMR experiments. Next the individual sugar rings are connected to their corresponding bases through intra-residue 1H-1H nuclear Overhauser effects (NOEs) observed in a 3D (1H, 13C, 1H) NOESY-HMQC experiment. Sequential NOE connectivities observed in this experiment are then used to assign each residue in the nucleotide sequence. The imino protons and nitrogens, and the cytidine amino protons and nitrogens, are assigned by 2D (15N, 1H) HMQC and 3D (1H, 15N, 1H) NOESY-HMQC experiments in H2O. This assignment procedure is illustrated on the 99% 13C/15N labeled RNA duplex r(GGCGCUUGCGUC)2. The application of these multi-dimensional heteronuclear magnetic resonance experiments enormously simplifies the resonance assignment of nucleic acids and allows assignment of many more protons, carbons and nitrogens than was possible using standard techniques on unlabeled molecules. Since a larger percentage of the protons can now be assigned by these experiments, much more NMR structural information can be obtained which will significantly extend the size limit for solution structure determinations of RNAs.

Base Sequence↗