Biomedical subjects

Luis Velasco

Publications and source records attributed to Luis Velasco.

4 recordsLinked to original sources

PubMed2005

Electron ionization mass spectra of indolenines obtained using sector and ion trap mass spectrometers.

The electron impact (EI)-induced fragmentations of 18 indolenines were studied using both double-focusing and ion trap mass spectrometers. The compounds used in this study were synthesized to provide correlations of characteristic fragment ions with specific structural differences. In 2-hydroxyindolenines the hydroxy group was involved in a major fragmentation process by interacting with the ester side chain to generate an alpha,beta-unsaturated gamma-lactone structure, with concomitant loss of the corresponding alcohol. In contrast, loss of an alkyl radical, derived solely from the 2-alkoxy group, is a major primary decomposition process for 2-alkoxyindolenines. EI-MS analyses using sector and ion trap spectrometers resulted in similar fragmentation patterns.

Journal Article↗

PubMed2005

Chemical composition and anti-inflammatory activity of the volatile fractions from the bark of eight Mexican Bursera species.

The volatile fractions from the bark of eight species of Mexican Bursera were obtained using steam distillation and were subjected to tandem GC-MS analysis for identification of the main constituents. The most abundant components of steam volatiles were monoterpenoids from which alpha-terpineol, terpinen-4-ol, alpha-thujene, linalool and limonene were most frequently isolated. A series of sesquiterpenes and long-chain hydrocarbons were isolated and identified from the barks of some of the studied species . Some volatiles were assayed for anti-inflammatory activity using the TPA-induced ear edema bioassay in mice. The volatile fraction from Bursera lancifolia was about half as active as indomethacin.

Animals↗

PubMed2003

Mass spectrometric studies of cyclopentanol derivatives in the reductive coupling of alpha,beta-unsaturated ketones assisted by samarium diiodide.

The mass spectrometric fragmentations of a series of cyclopentanol derivatives in positive fast-atom bombardment (FAB(+)) mode were investigated. The corresponding pathways proposed were confirmed by MS/MS data obtained using linked scans at constant B/E, high-resolution accurate mass data, and comparisons with corresponding information for a specifically deuterated molecule.

Cyclopentanes↗

PubMedDate not supplied

[ULCERATIVE COLITIS: A 52 YEARS RETROSPECTIVE STUDY]

We present a retrospective study on 74 patients with inespecific chronic ulcerative colitis according to diagnostic criteria. The higher incidence was present in patients between 30 and 40 years old. The most frequent symptom was diarrhea (95%), abdominal pain (79%), rectal bleeding (87%), rectal tenesmus (50%), weight loss (36%), and fever (18%). In relation to the degree of severity, we found that 33,7% suffered mild symptoms, 46,6% had moderate symptoms, while 17,7% suffered severe symptoms. The endoscopic findings were: 93,2% friability, 90,5% hyperemia, and 84,4% granulatio. Mortality was of 6,7%. We concluded that this disease is rare in Peru. The related mortailty is low, symptoms are mostly moderate, and no association with cancer of colon was evidenced.

Journal Article↗