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Biomedical subjects

E White

Publications and source records attributed to E White.

At least 343 records · Page 19Linked to original sources
PubMed1982

The accurate determination of serum glucose by isotope dilution mass spectrometry--two methods.

Two isotope dilution mass spectrometric methods have been developed for the determination of D-glucose in human serum. Each uses a uniformly labeled (13C)glucose as the internal standard. The first method involves conversion of glucose into 1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose and an extensive clean-up, followed by quantitation using packed column gas chromatography mass spectrometry. In the second method, glucose is converted into alpha-D-glucofuranose cyclic 1,2:3,5-bis(butylboronate)-6-acetate. The wet chemistry work-up is simpler, but analysis by capillary gas chromatography mass spectrometry is required. Both methods exhibit excellent precision (coefficients of variation less than 0.3%) and provided mean values that agree within 1% for all serum pools tested.

Blood Glucose↗
PubMed1981

Growth characteristics of MOPC-315 plasmacytoma and response to anticancer agents.

We examined the growth characteristics and response to anticancer agents of the murine plasmacytoma MOPC-315, a rapidly growing and widely disseminating tumor syngeneic in BALB/c mice. The doubling time for the tumor was approximately 24 hours, and about 1 in 100 cells was tumorigenic. We developed a spleen colony assay for the clonogenic component of the tumor and used it to define the dose-response relationships for various anticancer agents, including melphalan, cyclophosphamide, 1,3-bis(chloroethyl)-1-nitrosourea, 5-fluouracil, gamma-radiation, methotrexate, methylprednisolone, cytosine arabinoside, and vincristine.

Animals↗
PubMed1981

Mammographic practice and dosimetry in Britain.

A survey of mammographic techniques and dosimetry in 61 NHS centres in Britain has been completed. Physical parameters measured at each centre included tube output, half-value thickness, peak kilovoltage, surface dose and percentage depth dose. Ionisation and thermoluminescence dosimetry were employed and image quality was assessed subjectively using a test phantom. Absorbed doses are given at the plane surface of an average-sized, 5 cm thick homogenous breast composed of 50% fat and 50% water. The doses fall naturally into the four combinations of molybdenum (Mo) and tungsten (W) targets and film (F) and xerox (X) receptors. The Mo/X group produced the best images of the phantom but also the highest mean dose of 3.26 cGy (rad) for a cranio-caudad (c-c) view and its use does not seem justified for asymptomatic screening. The Mo/Lo-Dose or MIN-R film combination gave a mean dose of 0.95 cGy(rad) for a c-c view whereas the W/X group gave 0.89 cGy(rad) and superior image quality. The W/F group gave the poorest image quality and its continued use for mammography is questionable.

Female↗
PubMed1980

Total serum cholesterol by isotope dilution/mass spectrometry: a candidate definitive method.

We describe a highly accurate and precise method for determination of total cholesterol in serum by isotope dilution/mass spectrometry. The method was developed for a Study Group of the Committee on Standards of the American Association for Clinical Chemistry, for use in establishing the accuracy of a candidate reference method for total cholesterol, and fulfills their criteria for a definitive method. Cholesterol-d7 is added to serum, with the weight ratio of cholesterol-d7 to total serum cholesterol kept near to 1:1. The esters are hydrolyzed and the cholesterol is separated and converted into the trimethylsilyl ether derivative for measurement by combined gas chromatography/mass spectrometry. The intensity ratio of the molecular ions at m/z 465 and 458 is measured for each sample and for two calibration mixtures, according to a prescribed bracketing protocol. A weight ratio for the sample is obtained by linear interpolation of the ion-intensity ratios, and the total cholesterol is then calculated. The method was applied four times over several weeks to each of five serum pools. Statistical analysis involving consideration of both replication error and variability between weeks gave a coefficient of variation for a single measurement of 0.36%. The absence of interferences in the method was demonstrated by measurements at several other masses.

Carbon Radioisotopes↗