The concentration
of human serum albumin (HSA) indicates the health
state of individuals and is routinely measured by UV spectroscopy
with bromocresol. However, this method tends to overestimate HSA,
and more critically, depends highly on the timing, in seconds, of
the measurements. Here, we report an analog of 2′,7′-dichlorofluorescein
that can be used as a fluorescent sensor to quantify HSA in human
sera. The accuracy of this new method proved superior to that of bromocresol
when an international standard serum sample was analyzed. This method
is more convenient than the bromocresol method because it allows for
fluorescence measurements during a >15 min period. Colorimetric
analysis
was also performed to further investigate the effects of the binding
of the sensor to HSA. These spectroscopic studies suggest that absorption
and emission changes upon HSA binding may be due to the dehydration
of the dye and/or stabilization of the tritylic cation species.
The heterocyclic alkaloids, ceratamines A and B, are isolates from a marine Pseudoceratina sp. sponge. They behave as antimitotic agents, with IC50 values in the low micromolar range. The mechanism of this activity involves the disruption of microtubule dynamics; therefore, the ceratamines are of great interest in cancer drug discovery. Studies of in vitro metabolism were performed using rat liver microsomes to begin to understand the pharmacokinetics of these unique natural products. A total of eight metabolites were identified using UV and LC-MS/MS techniques. The majority of metabolites were formed as a result of various demethylation reactions. The formation of two metabolites, M1 and M3, involved monooxygenation, most likely on the aromatic ring, however the exact structure has not been determined. UV absorbance revealed a hypsochromic shift as a result of monooxygenation, an observation that may suggest the loss of aromaticity; however, further investigation is required. The structures of two major metabolites of ceratamine B, M4 and M6, were confirmed by (1)H NMR spectroscopy. These metabolites formed as a result of demethylation at the methoxy and aminoimidazole, respectively.
When Shannon Castro was a child, the rocks and minerals around her were more than playthings. They were objects for her to discover and explore. Unlike many fads in her preteen years, the desire to collect and study rocks remained at the forefront of her passions. By the time she entered high school in Texas, she was itching to try her hand at the science that had fascinated her for so long.
The Society of Exploration Geophysicists Foundation embarked on its mission more than 25 years ago, committed to “Advancing Geophysics Today and Inspiring Geoscientists for Tomorrow.” Although much has changed since 1986, that mind-set has not. The SEG Foundation wants to recognize our Trustee Associates (TA) for demonstrating their commitment to that mind-set.
Donor funds have enabled the SEG Foundation to provide more than $2.2 million on average over the last five years to SEG programs that are available to more than 33,000 members. Thanks to these donors' commitments, thousands of members have access to 16 excellent education and professional development programs.
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