RESUMO
In the past, silencing of granule-bound starch synthase (GBSSI) in potato was achieved by antisense technology, where it was observed that inclusion of the 3' end of the GBSSI coding region increased silencing efficiency. Since higher silencing efficiencies were desired, GBSSI inverted repeat constructs were designed and tested in potato. First, large inverted repeats comprising the 5' and the 3' half of the GBSSI cDNA were tested. The 5' IR construct gave a significantly higher silencing efficiency than the 3' IR construct. Since it was not known whether the observed difference was due to the sequence or the orientation of the inverted repeat, the GBSSI cDNA was divided into three regions, after which each region was tested in small inverted repeats in two orientations. To this end large numbers of independent transformants were produced for each construct. The results suggested that there was no effect of inverted repeat orientation on silencing efficiency. The percentage of transformants showing strong inhibition varied from 48% for a 3'-derived construct to 87% for a 5' as well as a middle region-derived construct. Similar to the large inverted repeats, the 3' sequences induced the least efficient silencing implying that the observed differences in silencing efficiency are caused by sequence differences. The small inverted repeat constructs with a repeat size of 500-600 bp and a spacer of about 150 bp were more efficient silencing inducers than the large inverted repeat constructs where the size of the repeat was 1.1 or 1.3 kb whilst the size of spacer was 1.3 or 1.1 kb. The results presented here show that size and sequence of the inverted repeat influenced silencing efficiency.
Assuntos
Interferência de RNA , Sequências Repetitivas de Ácido Nucleico/genética , Solanum tuberosum/enzimologia , Sintase do Amido/genética , Northern Blotting , DNA Antissenso/genética , DNA Bacteriano/genética , DNA Complementar/genética , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas , RNA de Plantas/genética , RNA de Plantas/metabolismo , Solanum tuberosum/genética , Solanum tuberosum/metabolismo , Amido/metabolismo , Sintase do Amido/metabolismoRESUMO
Combination therapy could be of benefit for the treatment of invasive yeast infections. However, in vitro interaction studies are relatively scarce and the interpretation of the fractional inhibitory concentration (FIC) index can be contradictory due to various definitions used; not all information on the interaction study is used in the index, and different MIC end points exist for different classes of drugs. Fitting an interaction model to the whole response surface and estimation of an interaction coefficient alpha (IC(alpha)) would overcome these objections and has the additional advantage that confidence intervals of the interaction are obtained. The efficacy of flucytosine (5FC) in combination with amphotericin B (AB) and fluconazole (FCZ) was studied against 35 yeast isolates in triplicate (Candida albicans [n = 9], Candida glabrata [n = 9], Candida krusei [n = 9], and Cryptococcus neoformans [n = 8]) using a broth microdilution checkerboard method and measuring growth after 48 h by a spectrophotometer. The FIC index and IC(alpha) were determined, the latter by estimation from the response surface approach described by Greco et al. (W. R. Greco, G. Bravo, and J. C. Parsons, Pharmacol. Rev. 47:331-385, 1995) by using a computer program developed for that purpose. For the 5FC-FCZ combination, the interactions determined by the IC(alpha) generally were in concordance with the interactions determined by the FIC index, but large discrepancies were found between both methods for the 5FC-AB combination. These could mainly be explained by shortcomings in the FIC approach. The in vitro interaction of 5FC-AB demonstrated variable results depending on the tested Candida isolate. In general, the 5FC-FCZ combination was antagonistic against Candida species, but for some Candida isolates synergism was found. For C. neoformans the interaction for both combinations was highly dependent on the tested isolate and the method used. Response surface approach is an alternative method for determining the interaction between antifungal agents. By using this approach, some of the problems encountered with the FIC were overcome.
Assuntos
Anfotericina B/farmacologia , Antifúngicos/farmacologia , Candida/efeitos dos fármacos , Fluconazol/farmacologia , Flucitosina/farmacologia , Algoritmos , Interações Medicamentosas , Testes de Sensibilidade Microbiana , Modelos BiológicosRESUMO
OBJECTIVE: To determine in preterm infants with a patent ductus arteriosus (PDA) the effect of indomethacin treatment on spontaneous motor activity. STUDY DESIGN: Motor activity was assessed from repeated videotape recordings in 32 preterm infants (=33 weeks gestation). Sixteen infants required indomethacin therapy for treatment of PDA, 16 were control infants, matched for gestational age. Indomethacin (0.2 mg/kg i.v. in 5 min) was given thrice, with an interval of 12 h. One-hour recordings were made immediately before and immediately after the first dose of indomethacin and 24 h later before and after the third dose. The same recording schedule was used for the control infants. The effects of indomethacin on quantity and quality of spontaneous motor activity were examined. RESULTS: A significant reduction in the quantity of several spontaneous movement patterns and an increase in the occurrence of rest periods were found following the first indomethacin administration (p < 0.01). Concerning the quality of general movements, a reduction in the speed was found (p < 0.05). Both effects were not found after the third indomethacin administration. CONCLUSION: In preterm infants with a PDA, treatment with indomethacin leads to a transient reduction in the quantity of spontaneous movement patterns and to a decrease in the speed of general movements. We recommend a cautious use of bolus indomethacin for the treatment of PDA.
Assuntos
Fármacos Cardiovasculares/uso terapêutico , Permeabilidade do Canal Arterial/tratamento farmacológico , Permeabilidade do Canal Arterial/fisiopatologia , Indometacina/uso terapêutico , Recém-Nascido Prematuro/fisiologia , Movimento/efeitos dos fármacos , Feminino , Humanos , Recém-Nascido , Masculino , Estudos Prospectivos , Valores de ReferênciaRESUMO
An 11 kb Eco RI genomic fragment containing the alcohol dehydrogenase (Adh1) gene was cloned. Cross-hybridization with three Adh2 cDNA clones suggested that the entire coding region of the Adh1 gene was contained on a 6.2 kb Xba I/Hind III subfragment. Using RFLP linkage analysis, the genomic clone was mapped on chromosome 4 between the markers TG 182 and TG 65 in a position corresponding to the Adh1 locus. To further confirm the Adh1 origin of the genomic clone, tobacco plants were transformed with the 6.2 kb Xba I/Hind III genomic subfragment. Isozyme analysis demonstrated that in transgenic tobacco plants functional tomato specific ADH-1 homodimers were synthesized as well as heterodimers composed of tobacco and tomato subunits.