New type of filaments for improved accuracy of multiple sulfur isotope analyses by electron-impact gas-source mass spectrometry.

Rationale: The analysis of the three sulfur stable isotope ratios (S/S, S/S, S/S) is routinely performed by gas-source isotope ratio mass spectrometry (IRMS) on the SF gaseous molecule, collecting SF ions at m/z ~ 127, 128, 129 and 131. High precision and accuracy are commonly achieved owing to a lack of correction because fluorine has only one isotope and the inert nature of the SF molecule. The analysis of the S/S ratio is, however, complicated by the low abundance of S (~0.

Improved analysis of micro- and nanomole-scale sulfur multi-isotope compositions by gas source isotope ratio mass spectrometry.

Rationale: Multiple sulfur isotope compositions are usually measured on relatively large samples (in the range of micromoles); however, sometimes only small amounts are available and thus it is necessary to analyze small (sub-micromole) samples. We report an improved method to measure multiple sulfur isotope compositions: δ(33) S, δ(34) S and δ(36) S values on the SF6 molecule (m/z 127, 128, 129, 131) for quantities down to 0.1 micromole, and δ(33) S and δ(34) S values for quantities down to 20 nanomoles.

Morphodynamics and pathology of blood vessels III--comparative morphologic study of contraction of smooth muscle cells of hollow viscera and its application to vasoconstriction and vasospasm.

The morphologic changes in the walls of hollow viscera caused by contraction and relaxation of smooth muscle cells were studied from autopsy and surgical specimens. The specimens studied included: esophageal spasm (corkscrew and nutcracker esophagus), contraction of the lower esophageal sphincter with marked esophageal dilatation, gaseous distension of the stomach, contraction of the gastric pylorus, bladder and anal sphincter, physiological segmental constriction of the small and large intestines, constriction and distension of the gallbladder, urinary bladder and bronchi, and postpartum contraction of the uterus. In contrast to distension, the constriction of hollow viscera shows marked reduction of the external circumference and diameter with thickening of the wall, contraction of smooth muscle cells, thickening of muscle bundles, remodeling of wall structure, and narrowing or obliteration of the lumen.