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At least 919 records · Page 51Linked to original sources
PubMed1989

Folic acid absorption determined by a single stool sample test--a double-isotope technique. The folic acid absorption capacity in children.

The fractional folic acid absorption (FAFol) was determined in 66 patients with various gastrointestinal diseases by a double-isotope technique, employing a single stool sample test (SSST) as well as a complete stool collection. The age of the patients ranged from 2.5 months to 16.8 years (mean 6.3 years). The test dose was administered orally and consisted of 50 micrograms of [3H]folic acid (monoglutamate) (approximately 20 muCi), carmine powder, and 2 mg 51CrCl3 (approximately 1.25 muCi) as the unabsorbable tracer. The whole-body radiation given to a 1-year-old child averaged 4.8 mrad only. The stool and napkin contents were collected and homogenized by the addition of 300 ml chromium sulfuric acid. A 300-ml sample of the homogenized stool and napkin contents, as well as 300 ml chromium sulfuric acid (75% vol/vol) containing the standards, were counted for the content of 51Cr in a broad-based well counter. The quantity of [3H]folic acid was determined by liquid scintillation, after duplicate distillation. Estimated by SSST, the FAFol, which employs the stool with the highest content of 51Cr corresponding to the most carmine-colored stool, correlated closely with the FAFol based on complete stool collection (r = 0.96, n = 39, p less than 0.0001). The reproducibility of FAFol determined by SSST was assessed from repeated tests in 18 patients. For a mean of 81%, the SD was 4.6%, which corresponded to a coefficient of variation of 5.7%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Lymph drainage from the vulva.

Fifty-four patients with cervical cancer stage Ib were injected preoperatively with 99mTc-colloid in different areas of the vulva and three controls in the axilla. The radioactivity in the groins and the pelvis was measured with a scintillation camera and in the removed pelvic lymph nodes with a well counter. A low activity could be measured in the removed pelvic nodes of the controls indicating the radioactivity which had reached the pelvic nodes via the bloodstream. Clitoris and perineum had a bilateral lymph flow. In all the other patients the vast majority of the radioactivity was found in the ipsilateral lymph nodes. A significant, but small amount of activity was recorded in the contralateral nodes in 67% of the patients and in all patients injected in the anterior part of the labium minus. The medial external iliac lymph chain had an uptake of 73% of the total activity measured in the removed pelvic nodes. Only in 13% of the patients was the activity higher in the lateral than in the medial external iliac chain. Direct lymphatic pathway from the clitoris to the pelvic lymph nodes was not found. Anastomoses exist probably in 13 out of 42 patients between the presacral and/or common iliac nodes on both sides.

Adult↗
PubMed2004

Construction of 144, 565 keV and 5.0 MeV monoenergetic neutron calibration fields at JAERI.

Monoenergetic neutron calibration fields of 144, 565 keV and 5.0 MeV have been developed at the Facility of Radiation Standards of JAERI using a 4 MV Pelletron accelerator. The 7Li(p,n)7Be and 2H(d,n)3He reactions are employed for neutron production. The neutron energy was measured by the time-of-flight method with a liquid scintillation detector and calculated with the MCNP-ANT code. A long counter is employed as a neutron monitor because of the flat response. The monitor is set up where the influence of inscattered neutrons from devices and their supporting materials at a calibration point is as small as possible. The calibration coefficients from the monitor counts to the neutron fluence at a calibration point were obtained from the reference fluence measured with the transfer instrument of the primary standard laboratory (AIST), a 24.13 cm phi Bonner sphere counter. The traceability of the fields to AIST was established through the calibration.

Algorithms↗
PubMed1987

[A study of the intestinal 47Ca absorption test employing a scintillation camera].

In order to evaluate the clinical application of the calcium absorption test from the intestine, the intestinal 47Ca absorption test by using a scintillation camera was carried out in our laboratory. The results in the intestinal 47Ca absorption test using a scintillation camera showed a good correlation to the results which were estimated by using an arm counter previously reported by us. The rate of intestinal 47Ca absorption in 8 healthy volunteers (5 male, 3 female, average age: 37.6 +/- 9.5 years) was 52.0 +/- 3.8%, 74.3% in a patient with primary hyperparathyroidism 30.4% and 32.7% in two patients with idiopathic hypoparathyroidism respectively. This method is more easily handled and can be performed for only 4 days in institutes that are set up with scintillation camera without any special preparations, and it is recommended to be of clinical usefulness for the diagnosis of calcium metabolic disorders.

Adult↗
PubMed1998

Distribution of energetic particles and secondary radiation according to orbital station "MIR" data obtained in 1991.

A set of instruments for measuring energetic particle fluxes, containing two neutron detectors under different plexiglas shielding thicknesses, a scintillation detector, measuring energy release >0.1 MeV and 0.5 MeV and a Geiger counter were launched onboard OS 'MIR'. The latitude dependencies of the cosmic ray measurements were obtained and studied. The distributions of primary particle fluxes (protons and elections) as well as secondary particle fluxes (bremsstrahlung gamma-rays and neutrons) produced in interactions of radiation belt particles with the station materials were obtained. The electron belt, generated during the storm of March 24 1991, is studied.

Cosmic Radiation↗
PubMedDate not supplied

Self-absorption correction in standardisation of 204Tl.

In the frame of the CCRI(II) (Consultative Committee for Ionizing Radiation at the BIPM) working group on 204Tl, dedicated to investigate the problem and explain the reasons for the discrepancy between methods in standardisation of 204Tl, IRMM was assigned the task of studying the influence of self-absorption in solid sources of 204Tl. This was investigated by measuring the activity of quantitative solid sources of different carrier content, prepared by employing a special source drying technique, developed at IRMM. The activity of the solid sources was determined using a 4pi pressurised proportional counter. The self-absorption was calculated using the activity determined from liquid scintillation spectrometry, unaffected by self-absorption, as the reference value. After correction for foil absorption and non-detected X-rays, the self-absorption showed a linear relation to the logarithm of the dry mass of the source. For a typical source, the self-absorption correction for 204Tl was found to be as high as 8%. This article describes a way to minimise and correct for self-absorption in solid sources of 204Tl or nuclides with similar decay properties.

Journal Article↗
PubMed1999

A solid-phase glycosyltransferase assay for high-throughput screening in drug discovery research.

Glycosyltransferases mediate changes in glycosylation patterns which, in turn, may affect the function of glycoproteins and/or glycolipids and, further downstream, processes of development, differentiation, transformation and cell-cell recognition. Such enzymes, therefore, represent valid targets for drug discovery. We have developed a solid-phase glycosyltransferase assay for use in a robotic high-throughput format. Carbohydrate acceptors coupled covalently to polyacrylamide are coated onto 96-well plastic plates. The glycosyltransferase reaction is performed with recombinant enzymes and radiolabeled sugar-nucleotide donor at 37 degrees C, followed by washing, addition of scintillation counting fluid, and measurement of radioactivity using a 96-well beta-counter. Glycopolymer construction and coating of the plastic plates, enzyme and substrate concentrations, and linearity with time were optimized using recombinant Core 2 beta1-6-N-acetylglucosaminyltransferase (Core 2 GlcNAc-T). This enzyme catalyzes a rate-limiting reaction for expression of polylactosamine and the selectin ligand sialyl-Lewis(x) in O-glycans. A glycopolymer acceptor for beta1-6-N-acetylglucosaminyltransferase V was also designed and shown to be effective in the solid-phase assay. In a high-throughput screen of a microbial extract library, the coefficient of variance for positive controls was 9.4%, and high concordance for hit validation was observed between the Core 2 GlcNAc-T solid-phase assay and a standard solution-phase assay. The solid-phase assay format, which can be adapted for a variety of glycosyltransferase enzymes, allowed a 5-6 fold increase in throughput compared to the corresponding solution-phase assay.

Acrylic Resins↗
PubMed1978

[A method for differentiating between vinegar produced by fermentation and vinegar made from synthetic acetic acid based on the determination of the specific 3H-radioactivity (author's transl)].

The applicability of the specific 3H-radioactivity for the distinction of synthetic and biogenic vinegar was tested. The acetic acid was isolated from the vinegar as calcium acetate, and the calcium acetate was combusted at 830 degrees C to CO2 and H2O. The water was measured either after two destillation steps by liquid scintillation counting or after reduction to hydrogen and reaction to ethane in a gas proportional counter. The difference in the 3H-content between the two types of vinegar in Austria is about 80--100 T.U. Since the level of activity is subject to appreciable annual fluctuations a series of synthetic and biogenic comparison samples always has to be included.

Acetates↗
PubMed1999

Modeling of scintillation camera systems.

Despite their widespread use, the satisfactory modeling of scintillation camera systems has remained difficult. Although the resolving time and deadtime T of a nonparalyzable counter are identical and also invariable, a distinction needs to be made between the fixed resolving time tau0 and the variable deadtime tau of a paralyzable counter. It is shown here that tau = tau0(e(n) - 1)/n, where n = Ntau0 = N/Nmax is the normalized input rate and N the absolute input rate. The normalized output rate, r = Rtau0, where R is the absolute output rate, has a maximum value r(max) = 1/e approximately 0.368 at the input rate n(max) = 1, where tau = tau0(e - 1) approximately 1.718tau0. It is also shown that the response of a system of nonparalyzable and paralyzable components at all input rates is determined by just the dominant nonparalyzable and paralyzable components in the system, the response at any particular input rate being that of the component with the higher of the two deadtimes T or tau. A system can be purely paralyzable (kT = T/tau0 < or = 1), combined paralyzable/nonparalyzable (1 < kT < or = 1.718), or essentially nonparalyzable (kT > 1.718), the combined paralyzable/nonparalyzable system having a lower nonparalyzable (T > tau) and an upper paralyzable (tau > T) operating range separated by a threshold input rate n(t) = ln(1 + kTn(t)) at which tau = T. A highly accurate and explicit expression for n(t) has also been derived. In the essentially nonparalyzable case, the system operates as nonparalyzable all the way up to the system's peak response point, which may occur at or above n(max) = 1. A two-component system with kT > 1 can also be described mathematically as nonparalyzable using r = n/(1 + k(tau)n), where k(tau) = tau/tau0 = kT for n < or = n(t), and k(tau) = (e(n) - 1)/n for n > or = n(t), or as paralyzable using r = ne(-nk0) with k0 = [ln(1 + kTn)]/n for n < or = n(t) and k0 = 1 for n > or = n(t). These alternative descriptions will be of considerable importance in the measurement of T and tau0 for such systems. The model described is able to account fully for the three different operating modes possible with scintillation camera systems.

Models, Theoretical↗