Calvin A. Lang

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSimple Microdetermination of Kjeldahl Nitrogen in Biological MaterialsC. A. LangCite this: Anal. Chem. 1958, 30, 10, 1692–1694Publication Date (Print):October 1, 1958Publication History Published online1 May 2002Published inissue 1 October 1958https://pubs.acs.org/doi/10.1021/ac60142a038https://doi.org/10.1021/ac60142a038research-articleACS PublicationsRequest reuse permissionsArticle Views668Altmetric-Citations472LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

1. Previous results from this laboratory demonstrated that the erythrocyte content of reduced glutathione (GSH) decreased as a function of both increasing cell age and mouse age [Abraham, Taylor & Lang (1978) Biochem. J. 174, 819-825]. In the present investigation glutathione concentrations were determined in other tissues of the C57BL/6J mouse of different ages (6--31 months) throughout the life-span. 2. At all ages the total glutathione and the GSH concentrations in liver were 3 times that in kidney and 10 times that in heart. In the old (31 months) mouse the GSH contents were lower by 30% in the liver, 34% in the kidney and 20% in the heart than in the mature (17--23 months) animals. 3. The oxidized glutathione (GSSG) concentrations of the tissues did not vary with age and constituted less than 3% of the total glutathione. 4. The decreased in GSH concentrations were not due to changes in organ weights, which were constant from 10 to 36 months of age. 5. These findings extend our previous results and indicate that a general characteristic of aging tissues may be a decrease in GSH concentrations. Further, this is consistent with our hypothesis that the reducing potential of tissues decreases in senescence.

The objective of this investigation was to test the hypothesis that blood glutathione levels are lower in aging human subjects as previously found in blood and tissues of standard rodent models of aging. Thus a study was conducted with 39 men and 130 women, 20 to 94 years old, who were selected by the criteria of being ambulatory, healthy, and free from diabetes mellitus, thyroid disease, anemias, and cancer. The reference group was comprised of the 20- to 39-year-old subjects, whose blood glutathione levels were 547 +/- 53.5 micrograms/10(10) erythrocytes (mean +/- SD) for 40 individuals and defined the reference range (95% confidence limits) of 440 to 654. Based on the 440 micrograms/10(10) erythrocyte cutoff, the incidence of low blood glutathione content in the older subjects increased significantly, particularly in the 60- to 79-year-old group. Their glutathione levels were 452 +/- 86.8 micrograms/10(10) erythrocytes, 17% lower than the reference group (p < 0.001). These findings demonstrate an increased incidence of low glutathione levels in apparently healthy elderly subjects, who thus may be at risk because of a decreased capacity to maintain many metabolic and detoxification reactions mediated by glutathione.

[1] We have successfully reproduced the Ozone ENSO Index (OEI) in the Goddard Earth Observing System (GEOS) chemistry-climate model (CCM) forced by observed sea surface temperatures over a 25-year period. The vertical ozone response to ENSO is consistent with changes in the Walker circulation. We derive the sensitivity of simulated ozone to ENSO variations using linear regression analysis. The western Pacific and Indian Ocean region shows similar positive ozone sensitivities from the surface to the upper troposphere, in response to positive anomalies in the Niño 3.4 Index. The eastern and central Pacific region shows negative sensitivities with the largest sensitivity in the upper troposphere. This vertical response compares well with that derived from SHADOZ ozonesondes in each region. The OEI reveals a response of tropospheric ozone to circulation change that is nearly independent of changes in emissions and thus it is potentially useful in chemistry-climate model evaluation.