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Biomedical subjects

Walter C Taylor

Publications and source records attributed to Walter C Taylor.

13 recordsLinked to original sources

Update on exercise stress testing.

Exercise stress testing is an important diagnostic tool for the evaluation of suspected or known cardiac disease. In 2002, the American College of Cardiology (ACC) and the American Heart Association (AHA) revised their guidelines for exercise testing. Ten categories from the ACC/ AHA 1997 guidelines were modified: ST heart rate adjustment, unstable angina, older patients, acute coronary syndromes, chest pain centers, acute myocardial infarction, asymptomatic patients, valvular heart disease, rhythm disturbances, and hypertension. Adjustment of the ST heart rate can identify myocardial ischemia in asymptomatic patients with elevated cardiac risk. Intermediate- and low-risk patients with unstable angina, acute coronary syndromes, or chest pain should undergo exercise stress testing when clinically stable. Provided they are stable, patients who have had acute myocardial infarction can undergo a submaximal exercise test before discharge or a symptom-limited exercise stress test any time after two to three weeks have elapsed. In asymptomatic patients with cardiac risk factors, the exercise stress test may provide valuable prognostic information. Aortic regurgitation is the only valvular heart disorder in which there is significant evidence that exercise stress testing is useful in management decisions. The stress test also can be used in older patients to identify the presence of coronary artery disease. However, because of other comorbidities, a pharmacologic stress test may be necessary. Exercise stress testing can help physicians successfully evaluate arrhythmia in patients with syncope. The exercise stress test also can help identify patients at risk of developing hypertension if they show an abnormal hypertensive response to exercise.

Age Factors↗

Prenylated xanthones as potential antiplasmodial substances.

Mangostin, the major xanthone of Garcinia mangostana, and a series of synthetic derivatives were investigated for their in vitro antiplasmodial activity against Plasmodium falciparum. Mangostin itself showed moderate activity, but prenylated xanthones containing alkylamino functional groups exhibited quite potent antiplasmodial activity. Some structure-activity relationships are proposed.

Animals↗

Tetraoxygenated xanthones from the fruits of Garcinia cowa.

Tetraoxygenated xanthones, cowaxanthones A-E, together with 10 previously reported tetraoxygenated xanthones, were isolated from the crude hexane extract of the fruits of Garcinia cowa. Cowaxanthone B has previously been reported as a synthetic xanthone. Their structures were elucidated by analysis of spectroscopic data, especially by 1D and 2D NMR. The antibacterial activities of the isolated compounds were also evaluated.

Anti-Bacterial Agents↗

Antibacterial caged-tetraprenylated xanthones from the stem bark of Garcinia scortechinii.

Five new caged-tetraprenylated xanthones, scortechinones L - P (1-5), together with six known scortechinones (A, B, D, F, I and J) and one known xanthone, 4 '',5 ''-dihydro-1,5-dihydroxy-6 ',6 '-dimethylpyrano(2 ',3 ':6,7)-4 '',4 '',5 ''-trimethylfurano(2 '',3 '':3,4)- xanthone, were isolated from the crude methanol extract of the stem bark of Garcinia scortechinii. The structures were elucidated by analysis of spectroscopic data and comparison of the NMR data with those reported previously. The antibacterial activity of all caged-polyprenylated xanthones, isolated from the latex and stem bark of G. scortechinii, was evaluated. Scortechinone B (6) exhibited significant antibacterial activity against a methicillin-resistant Staphylococcus aureus strain with an MIC value of 2 microg/mL. From the MIC values, some structure-antibacterial activity relationships were established.

Anti-Bacterial Agents↗

NMR studies of darutoside, a rare ENT-pimarane glucoside.

NMR spectral data in various solvents (DMSO-d6, CD3OD, C5D5N) for the rare ent-pimar-8(14)-ene-15, 16-diol 3-O-beta-D-glucoside, darutoside, are reported. Complete assignments are made on the basis of 1D and 2D (COSY, HMQC, HMBC, NOESY) spectra.

Asteraceae↗

Xanthones from the stem bark of Garcinia nigrolineata.

Nine xanthones, nigrolineaxanthones A-I, together with nine known xanthones, were isolated from the crude methanol extract of the stem bark of Garcinia nigrolineata; two of which have previously been reported as synthetic xanthones. The structures were elucidated by analysis of spectroscopic data, especially using 1D and 2D NMR spectroscopic data.

Garcinia↗

Caged-triprenylated and -tetraprenylated xanthones from the latex of Garcinia scortechinii.

The latex of Garcinia scortechinii has yielded eight new caged-polyprenylated xanthones: two triprenylated (1 and 2) and five tetraprenylated xanthones (3-7) and one degraded caged-tetraprenylated xanthone (8), together with the known scortechinones A (9) and B (10). Their structures were elucidated by analysis of spectroscopic data and comparison of the NMR data with those reported previously.

Bridged-Ring Compounds↗

Antibacterial xanthones from the leaves of Garcinia nigrolineata.

Ten new 1,3,5-trioxygenated xanthones, nigrolineaxanthones J-S (1-10), one new quinone derivative, nigrolineaquinone A (11), and one new isoflavone-like compound, nigrolineaisoflavone A (12), were isolated from the leaves of Garcinia nigrolineata along with four known xanthones and friedelin. Among the xanthones, only nigrolineaxanthone N (5) showed significant antibacterial activity against methicillin-resistant Staphylococcus aureus.

Anti-Bacterial Agents↗

Anti-HIV-1 protostane triterpenes and digeranylbenzophenone from trunk bark and stems of Garcinia speciosa.

Three new protostanes, garciosaterpenes A ( 1), B ( 2) and C ( 3), together with a new digeranylbenzophenone, garciosaphenone A ( 4) were isolated from the ethyl acetate fractions obtained from the crude methanol extracts of the trunk bark and stems of Garcinia speciosa. The structures were elucidated by spectroscopic methods and chemical reactions. Compounds 1 and 3 showed significant inhibitory activities (IC (50) 15.5 and 12.2 microg/mL, respectively) against HIV-1 reverse transcriptase and in the syncytium assay (EC (50) 5.8 microg/mL with TI 3.4 and 37.0 microg/mL with TI 1.9, respectively). Compound 4 was active in HIV-1 RT assay (IC (50) 23.9 microg/mL), but toxic in the syncytium assay. This work represents the first report on the anti-HIV-1 activities of the protostane triterpenes.

Anti-HIV Agents↗

Anti-inflammatory cyclohexenyl chalcone derivatives in Boesenbergia pandurata.

The cyclohexenyl chalcone derivative [(-)-hydroxypanduratin A], together with the previously known panduratin A, sakuranetin, pinostrobin, pinocembrin, and dihydro-5,6-dehydrokawain were isolated from the chloroform extract of the red rhizome variety of Boesenbergia pandurata (Robx.) Schltr. [currently known as Boesenbergia rotunda (L.) Mansf., Kulturpfl.]. Their structures were assigned on the basis of their spectroscopic data. (-)-Hydroxypanduratin A and (-)-panduratin A showed significant topical anti-inflammatory activity in the assay of TPA-induced ear edema in rats.

Animals↗

Isoflavone glycosides from Derris scandens.

Five isoflavone glycosides, named derriscandenosides A-E (1-5), were isolated from the stems of Derris scandens, together with ten known compounds comprising one isoflavone, two benzoic acid derivatives, three glucosyl isoflavones and four rhamnosyl-(1-->6)-glucosyl isoflavones. The structures of the glycosides were assigned on the basis of spectroscopic data, especially of the acetate derivatives. Three known rhamnosyl-(1-->6)-glucosyl isoflavones isolated from a crude fraction were retested for hypotensive activity with varying results.

Carbohydrate Conformation↗