scholarly journals DETERMINATION OF IODINE CONCENTRATION AND DISTRIBUTION IN RAT THYROID FOLLICLES BY ELECTRON-PROBE MICROANALYSIS

1969 ◽  
Vol 43 (1) ◽  
pp. 115-121 ◽  
Author(s):  
William L. Robison ◽  
David Davis
Keyword(s):  
Sample Preparation ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Freeze Drying ◽  
Iodine Concentration ◽  
Sodium Concentration ◽  
Thyroid Glands ◽  
The Mean ◽  
Rat Thyroid

The concentration and the distribution of iodine in various sized follicles of rat thyroid glands have been analyzed by electron-probe microanalysis. The results of the iodine analysis were grouped according to uncorrected lumen diameter size. No significant differences in iodine concentration were observed among the various size categories. When the results for all follicles from a given sample were pooled, the standard error of the mean was approximately 4%. Usually 40–50 follicles per animal were analyzed. The concentration of iodine ranged from 0.9 to 2.1% by weight among individual animals. Scanning pictures and step-scan analysis showed the iodine distribution to be quite uniform across the colloid area. Several techniques of sample preparation were used; they produced no significant differences in the iodine concentrations observed. Sodium concentration, also determined in all samples, was found to vary from 2 to 9% by weight. Because of the mobility of the sodium ion, its distribution was greatly affected by the method of sample preparation. The technique that best preserved the natural chemistry of the sample was that of freezing the tissue, sectioning, and then freeze-drying.

Determination of the mean size of submicron particles by electron probe microanalysis

1995 ◽  
Vol 24 (1) ◽  
pp. 13-18 ◽  
Author(s):  
A. Berner ◽  
I. Levin ◽  
L. Klinger ◽  
D. G. Brandon
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Submicron Particles ◽  
Mean Size ◽  
The Mean

scholarly journals A Toolbox for the Determination of Nitroaromatic Explosives in Marine Water, Sediment, and Biota Samples on Femtogram Levels by GC-MS/MS

Toxics ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 60
Author(s):  
Tobias Hartwig Bünning ◽  
Jennifer Susanne Strehse ◽  
Ann Christin Hollmann ◽  
Tom Bötticher ◽  
Edmund Maser
Keyword(s):  
Sample Preparation ◽  
Freeze Drying ◽  
Solid Phase ◽  
Phase Extraction ◽  
Direct Extraction ◽  
Time Saving ◽  
Marine Samples ◽  
Volume Method ◽  
Biota Samples

To determine the amount of the explosives 1,3-dinitrobenzene, 2,4-dinitrotoluene, 2,4,6-trinitrotoluene, and its metabolites in marine samples, a toolbox of methods was developed to enhance sample preparation and analysis of various types of marine samples, such as water, sediment, and different kinds of biota. To achieve this, established methods were adapted, improved, and combined. As a result, if explosive concentrations in sediment or mussel samples are greater than 10 ng per g, direct extraction allows for time-saving sample preparation; if concentrations are below 10 ng per g, techniques such as freeze-drying, ultrasonic, and solid-phase extraction can help to detect even picogram amounts. Two different GC-MS/MS methods were developed to enable the detection of these explosives in femtogram per microliter. With a splitless injector, limits of detection (LODs) between 77 and 333 fg/µL could be achieved in only 6.25 min. With the 5 µL programmable temperature vaporization—large volume method (PTV-LVI), LODs between 8 and 47 fg/µL could be achieved in less than 7 min. The detection limits achieved by these methods are among the lowest published to date. Their reliability has been tested and confirmed by measuring large and diverse sample sets.

Freeze-drying enables homogeneous and stable sample preparation for determination of fecal short-chain fatty acids

2020 ◽  
Vol 589 ◽  
pp. 113508 ◽  
Author(s):  
Jun Ueyama ◽  
Masaya Oda ◽  
Masaaki Hirayama ◽  
Kuniyo Sugitate ◽  
Norihiro Sakui ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Sample Preparation ◽  
Freeze Drying ◽  
Short Chain Fatty Acids ◽  
Short Chain ◽  
Chain Fatty Acids

A sample preparation for quantitative determination of magnesium in individual lymphocytes by electron probe X-ray microanalysis

1986 ◽  
Vol 141 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Gregory R. Hook ◽  
Ronald J. Elin ◽  
Jeanette M. Hosseini ◽  
Carol Swyt ◽  
Charles E. Fiori
Keyword(s):  
Sample Preparation ◽  
Quantitative Determination ◽  
Electron Probe ◽  
X Ray

scholarly journals Empiric Determination of the Daily Glucocorticoid Replacement Dose in Adrenal Insufficiency

2020 ◽  
Vol 4 (11) ◽  
Author(s):  
Celina M Caetano ◽  
Aleksandra Sliwinska ◽  
Parvathy Madhavan ◽  
James Grady ◽  
Carl D Malchoff
Keyword(s):  
Blood Pressure ◽  
Body Mass Index ◽  
Adrenal Insufficiency ◽  
Serum Sodium ◽  
Sodium Concentration ◽  
Cortisol Secretion ◽  
Endocrine Society ◽  
The Mean ◽  
Multiple Morbidities

Abstract Background For the treatment of adrenal insufficiency (AI) in adults, the Endocrine Society’s recommended daily glucocorticoid replacement dose (DGRD) is 15 to 25 mg hydrocortisone (HC), which is approximately 1.7 times the reported mean daily cortisol production rate. Prolonged glucocorticoid overtreatment causes multiple morbidities. Hypothesis We tested the hypotheses that the DGRD, empirically determined by individual patient titration, is lower than that of the Endocrine Society guidelines and tolerated without evidence of glucocorticoid under-replacement. Methods We empirically determined the DGRD in 25 otherwise healthy adults with AI by titrating the DGRD to the lowest dose tolerated as judged by body mass index, blood pressure, serum sodium concentration and AI symptoms. Patients received either HC or prednisone (PRED). The HC equivalent of PRED was assumed to be 4:1. Results The mean empirically determined DGRD, expressed as HC equivalent, was significantly less than the midpoint of the Endocrine Society’s recommended DGRD (7.6 ± 3.5 mg/m2 vs 11.8 mg/m2; P < 0.001). The DGRD in the adrenalectomy group was not significantly different than the DGRD of those with other AI causes (7.9 ± 4.0 mg/m2 vs 7.3 ± 3.1 mg/m2; P = ns), demonstrating that the empirically determined DGRD was not biased by residual cortisol secretion. There was no evidence of glucocorticoid under-replacement as determined by measured biometrics and AI symptoms. Conclusions We conclude that an empirically determined DGRD is significantly lower than that of the Endocrine Society guidelines and tolerated without evidence of glucocorticoid under-replacement.

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