Dvopulsni sustav za isporuku amoksicilina: Pokušaj sprečavanja bakterijske rezistencije na antibiotike

Bearing in mind the present scenario of the increasing biological tolerance of bacteria against antibiotics, a time controlled two pulse dosage form of amoxicillin was developed. The compression coating inlay tablet approach was used to deliver the drug in two pulses to different parts of the GIT after a well defined lag time between the two releases. This was made possible by formulating a core containing one of the two drug fractions (intended to be delivered as the second pulse), which was spray coated with a suspension of ethyl cellulose and a hydrophilic but water insoluble agent as a pore former (microcrystalline cellulose). Coating of 1 up to 5 % (m/m) was applied over the core tablet, giving a corresponding lag of 3, 5, 7 and 12 h. Increasing the level of coating led to retardation of the water uptake capacity of the core, leading to prolongation of the lag time. Microcrystalline cellulose was used as a hydrophilic but water insoluble porosity modifier in the barrier layer, varying the concentration of which had a significant effect on shortening or prolongation of the lag time. This coated system was further partially compression coated with the remaining drug fraction (to be released as the first immediate release pulse) with a disintegrant, giving a final tablet. The core tablet and the final two pulse inlay tablet were further investigated for the in vitro performance.Zbog sve učestalije pojave rezistencije bakterija na antibiotike, razvijen je dvopulsni sustav s vremenskom kontrolom za isporuku amoksicilina. Sustav čine slojevite tablete s obloženim slojem dobivenim metodom kompresije, koji omogućavaju isporuku lijeka u dva pulsa u različite dijelove gastrointestinalnog trakta, s utvrđenom odgodom između dva oslobađanja. Ovakav način oslobađanja postignut je s pripravkom koji u jezgri tablete sadrži jednu frakciju lijeka (koja se oslobađa kao drugi puls), a u oblozi drugu. Obloženi dio dobiven je sprejanjem sa suspenzijom etilceluloze i hidrofilnog, ali vodonetopljivog sredstva koji tvori pore (mikrokristalinična celuloza). Oblaganje sa slojem koji čini 1 do 5 % (m/m) mase jezgre postignut je vremenski odmak drugog pulsa od 3, 5, 7 i 12 h. Povećanjem mase obložnog sloja smanjuje se kapacitet prodiranja vode u jezgru tablete, što produljuje vrijeme drugog pulsa. Mikrokristalinična celuloza uporijebljena je kao hidrofilno, vodonetopljivo sredstvo za kotrolu poroznosti u barijernom sloju. Promjena koncentracije celuloze značajno je utjecala na skraćenje ili produljenje vremenskog odmaka. Obloženi sustav je potom djelomično obložen s preostalom frakcijom lijeka (koja se oslobađa odmah u prvom pulsu) pomiješanom s dezintegratorom. Tableta s jezgrom i dvopulsna slojevita tableta ispitivane su in vitro

Boron Stress Responsive MicroRNAs and Their Targets in Barley

Boron stress is an environmental factor affecting plant development and production. Recently, microRNAs (miRNAs) have been found to be involved in several plant processes such as growth regulation and stress responses. In this study, miRNAs associated with boron stress were identified and characterized in barley. miRNA profiles were also comparatively analyzed between root and leave samples. A total of 31 known and 3 new miRNAs were identified in barley; 25 of them were found to respond to boron treatment. Several miRNAs were expressed in a tissue specific manner; for example, miR156d, miR171a, miR397, and miR444a were only detected in leaves. Additionally, a total of 934 barley transcripts were found to be specifically targeted and degraded by miRNAs. In silico analysis of miRNA target genes demonstrated that many miRNA targets are conserved transcription factors such as Squamosa promoter-binding protein, Auxin response factor (ARF), and the MYB transcription factor family. A majority of these targets were responsible for plant growth and response to environmental changes. We also propose that some of the miRNAs in barley such as miRNA408 might play critical roles against boron exposure. In conclusion, barley may use several pathways and cellular processes targeted by miRNAs to cope with boron stress

Ion homeostasis in the Chloroplast

peer reviewedThe chloroplast is an organelle of high demand for macro- and micro-nutrient ions, which are required for the maintenance of the photosynthetic process. To avoid deficiency while preventing excess, homeostasis mechanisms must be tightly regulated. Here, we describe the needs for nutrient ions in the chloroplast and briefly highlight their functions in the chloroplastidial metabolism. We further discuss the impact of nutrient deficiency on chloroplasts and the acclimation mechanisms that evolved to preserve the photosynthetic apparatus. We finally present what is known about import and export mechanisms for these ions. Whenever possible, a comparison between cyanobacteria, algae and plants is provided to add an evolutionary perspective to the description of ion homeostasis mechanisms in photosynthesis