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Biomedical subjects

A Bermejo

Publications and source records attributed to A Bermejo.

29 records · Page 2Linked to original sources
PubMed1992

Tetrandrine and isotetrandrine, two bisbenzyltetrahydroisoquinoline alkaloids from Menispermaceae, with rat uterine smooth muscle relaxant activity.

The effects of two bisbenzyltetrahydroisoquinoline alkaloids, 1S,1'S tetrandrine and its isomer 1R,1'S isotetrandrine, were investigated in rat isolated uterus in order to identify the mechanism of relaxant action and to study the influence of the absolute configuration on the activity of these alkaloids. Both inhibited the uterine contraction induced by high K+, acetylcholine and oxytocin. In Ca(2+)-free medium, isotetrandrine relaxed the sustained contraction induced by oxytocin but tetrandrine did not. The relaxant effects of the alkaloids may be due to blockade of calcium influx through specific channels. Tetrandrine and isotetrandrine modify the calcium channel in a nonreversible manner whilst only isotetrandrine acts intracellularly. Tetrandrine shows a more specific relaxant activity as a calcium entry blocker.

Acetylcholine↗
PubMed1992

Insecticide-impregnated bed nets for malaria control: a review of the field trials.

Insecticide-impregnated bed nets act as a physical barrier to repel and kill mosquitos. Community intervention trials suggest that these nets are effective in preventing malaria-related mortality and morbidity--but not malaria infection--in areas of low and moderate transmission; the results from areas of high transmission are not so encouraging. Comparison of the results from these trials and their interpretation are difficult because of variations in the epidemiology of malaria and several methodological flaws. Problems such as defining appropriate health indicators, monitoring bed-net usage, introducing bed nets randomly, selecting adequate controls, performing statistical analysis, and comparing bed nets with other available interventions are considered. Further community intervention trials are needed, paying attention to the methods and to assessment of their impact on malaria.

Animals↗
PubMed1990

Lichen planus with simultaneous involvement of the oral cavity and genitalia.

Five women with reticular and/or erosive lichen planus of the oral cavity associated with mucous involvement of the genitalia are reported. The presence of a typical lesion in one of these sites requires search for other common sites of involvement as well as manifestations of systemic diseases. Early management and careful follow-up of patients with chronic erosive and atrophic lesions of the vulva should be instituted to prevent dyspareunia. The use of the term plurimucosal lichen planus instead of vulvo-vagino-gingival syndrome is proposed.

Adult↗
PubMed1985

Treatment of lichen planus with griseofulvin. Report of seven cases.

Seven patients with lichen planus of the oral mucosa (four with erosive and three with reticular types of the disease) were studied; they were treated with 500 mg of griseofulvin twice daily for 2 1/2 months. In no case was improvement observed; on the contrary, in four patients (two with erosive and two with reticular forms) the condition worsened.

Adult↗
PubMedDate not supplied

Application of derivative spectroscopy to the determination of plasma theophylline in the presence of phenobarbital.

A rapid, simple, and sensitive procedure for the determination of theophylline in plasma using second derivative spectroscopy is described. Second derivative spectra of plasma extracts containing theophylline in concentrations ranging from 2 to 20 micrograms/mL were studied. The method is suitable for the measurement of plasma theophylline in patients treated for cardiorespiratory disorders. Interference from other compounds such as phenobarbital can be avoided.

Chemical Phenomena↗
PubMedDate not supplied

Speciation of zinc in low molecular weight proteins of breast milk and infant formulas by size exclusion chromatography/flame atomic absorption spectroscopy.

Size exclusion chromatography (SEC) and flame atomic absorption spectroscopy (FAAS) were used for the separation of metal-containing species in milk whey. After milk ultracentrifugation, the sample was injected into a TSK-Gel G2000 glass column and eluted with 0.2M NH4NO3-NH3, pH 6.7. Low molecular weight proteins were fractionated, and the fractions were characterized by molecular weight. Zinc distributions were obtained by FAAS using a high performance nebulizer. The method was very sensitive (limit of detection = 2.6 x 10(-3) microg/mL; limit of quantitation = 8.9 x 10(-3) microg/mL) and precise (RSDs < or =10%). This method was applied to the determination of Zn in binding compounds in breast milk whey and in commercial cow's milk-based formulas. Distribution patterns were different. The presence of Zn in most fractions in breast milk was most significant, whereas in infant formulas Zn was detected only in fractions of molecular weight <5 kDa and in the highest molecular weight peak.

Calibration↗
PubMedDate not supplied

Cytotoxic compounds from Annonaceus species as DNA topoisomerase I poisons.

BACKGROUND: In the search for cytotoxic natural products as DNA topoisomerase poisons, we have assessed six annonaceus compounds (the acetogenins annonacin and rolliniastatin-1, the styryl-lactones etharversin and altholactone and the alkaloids thaligrisine and cepharanone-B) for cytotoxic activity against three human cancer cell lines and then we evaluated these compounds as DNA topoisomerase poisons. MATERIALS AND METHODS: The cytotoxicity parameters were determined following protocols established by the National Cancer Institute (NCI) using the SRB assay. In the topoisomerase assay, the supercoiled DNA produces open circle forms that are stabilised in the presence of DNA topoisomerase poisons and can be detected after a denaturation step by proteinase K-SDS. RESULTS: The six compounds showed cytotoxic activity, with cepharanone B being the most cytotoxic one, even more than the antineoplastic agent etoposide on two cancer cell lines, although it is the only one that does not act as a DNA topoisomerase poison. CONCLUSION: These results could justify the traditional use of the studied annonaceus species and topoisomerase-mediated DNA damage might be a possible mechanism by which five of these compounds exert their cytotoxicity.

Annonaceae↗