Physiological and pathological factors affecting absorption of drugs

Absorpce léčiv z gastrointestinálního traktu po perorálním podání je klíčovým farmakokinetickým procesem spoluurčujícím následnou farmakodynamickou odpověď organismu a terapeutickou účinnost. Tato dizertační práce je věnována studiu faktorů, které tento proces ovlivňují. Zvláštní důraz je kladen na studium lymfatické absorpce, tj. míry vstřebávání účinné látky cestou intestinálního lymfatického systému. Byla provedena řada in vivo studií na laboratorních potkanech. Farmakokinetické studie byly prováděny pomocí pravidelných odběrů krve z cévních katetrů po perorálním podání léčiva. Lymfatická absorpce byla zkoumána na modelu anestezovaného potkana se zakanylovaným mezenterickým lymfatickým duktem. Testovány byly moderní léky, které byly spolupracujícími chemicko-technologickými pracovišti upraveny do inovativních lékových forem. Abirateron acetát, lipofilní látka používaná v terapii karcinomu prostaty, se dobře vstřebával z trávicího traktu po podání ve formě olejových kuliček (oil marbles). Touto technologií se též podařilo snížit jinak velmi výrazný pozitivní vliv jídla. Abirateron acetát se nevstřebával ve významné míře cestou intestinálního lymfatického systému. Lymfatická absorpce cinakalcetu, látky používané k léčbě hyperparatyreózy, byla naopak výrazná. Relativní podíl lymfatické absorpce na...Absorption of drugs from the gastrointestinal tract after oral administration is a key pharmacokinetic process co-determining the subsequent pharmacodynamic response of the organism and therapeutic efficacy. This dissertation thesis is devoted to the study of factors that influence this parameter. Special emphasis is placed on the study of lymphatic absorption, i.e. the rate of absorption of the active substance via the intestinal lymphatic system. A number of in vivo studies have been carried out in laboratory rats. Pharmacokinetic studies have been performed by means of regular blood sampling from vascular catheters after oral administration of the drug. Lymphatic absorption was investigated in an anaesthetized mesenteric lymphatic duct cannulated rat model. Modern drugs were tested that were incorporated into innovative dosage forms by collaborating chemical and technological institutions. Abiraterone acetate, a lipophilic agent used in the therapy of prostate cancer, was well absorbed from the gastrointestinal tract after administration in the form of oil marbles. This technology also succeeded in reducing the otherwise very significant positive food-effect. Abiraterone acetate was not absorbed to any significant extent via the intestinal lymphatic system. In contrast, lymphatic absorption of...Farmakologický ústav 1. LF UK a VFNInstitute of Pharmacology First Faculty of Medicine Charles University and General University Hospital in Prague1. lékařská fakultaFirst Faculty of Medicin

Population genetic structure of Mycosphaerella graminicola and Quinone Outside Inhibitor (QoI) resistance in the Czech Republic

Damage caused by the wheat pathogen Mycosphaerella graminicola increased rapidly during the last two decades in the Czech Republic. We collected isolates from naturally infected fields in seven wheat-growing locations and analysed these using eight microsatellite markers. All markers were highly polymorphic. We found a high degree of genetic diversity and low clonality within all sampled Czech populations. We identified 158 unique multilocus haplotypes among 184 isolates. Field populations showed weak genetic structure but we detected more differentiation between climatic regions within the Czech Republic. We compared the Czech field populations to populations from the United Kingdom, Germany and Switzerland and found a marked differentiation between Czech populations and Western European populations. We hypothesize that decades of different agricultural practices, including the use of different wheat cultivars, may explain this genetic differentiation. We detected a rapid increase in QoI fungicide resistance during the sampling period from 2005 to 2011, coinciding with the widespread application of this class of fungicides in the Czech Republic. M. graminicola populations in the Czech Republic underwent a rapid adaptive evolution from sensitivity to resistance similar to what was described earlier in Western Europ

Apple mosaic virus

Apple mosaic, rose mosaic, plum and birch line pattern, horse chestnut yellow mosaic, and hazel mosaic are some of many diseases caused by one of the longest-known pome fruit viruses: Apple mosaic virus. The worldwide distribution of Apple mosaic virus and its negative impacts on fruit, nut and hop production are sufficient to cause international interest. This review endeavors to piece together all known information about the virus. We describe taxonomic position, virion structure, the host range and symptoms, modes of transmission and diagnostics for the virus, as well as distribution and control of the diseases it causes

Insights into the structure and phylogeny of the 28S rRNA expansion segments D2 and D3 of the plant-infecting nematodes from the genus Ditylenchus (Nematoda: Anguinidae)

Recently, it has been shown that the stem nematode, Ditylenchus dipsaci (Nematoda: Anguinidae), is genetically more related to the gall-forming nematodes from genera Anguina, Heteroanguina, and Mesoanguina than to other members of the genus Ditylenchus. This finding was provided by molecular data written in the evolutionary variable, non-coding internal transcribed spacers (ITS1 and ITS2) of the ribosomal DNA (rDNA). In the current paper, we analyze the nucleotide sequences and predict the secondary structures of two expansion segments (D2, D3) of the 28S ribosomal RNA (rRNA)-coding gene for the plant-parasitic nematodes from the genus Ditylenchus and their related anguinids. In general, the expansion segment D2 appeared to be more variable than the segment D3 illustrating their different evolutionary constraints. Comparative analysis of the aligned sequences and predicted secondary structures revealed similar trend showing the tight relationships between the stem nematodes (D. dipsaci, D. gigas, D. weischeri) and gall-forming nematodes from the subfamily Anguininae. Phylogeny reconstructions disjoined the family Anguinidae into two monophyletic clusters (Clade 1 and 2). Clade 1 constitutes the stem nematodes (D. dipsaci, D. gigas, etc) and gall-forming nematodes from the genera Anguina, Heteroanguina, Subanguina and Mesoanguina, while clade 2 includes other Ditylenchus species like D. destructor and D. halictus. Collectively, deciphering the exact phylogenetic relationships within the family Anguinidae (Nematoda: Tylenchida) with respect to our results should provide a framework for a taxonomic revision in order to reflect biological history of these nematodes. In addition, we provide novel molecular data, which may be exploited in diagnostic tools for phytosanitary control of these economically important plant parasites

Permeable membranes PUR/TETA and PUR/TEPA for CO2 capture prepared with one-step electrospinning technology

A simple one-step technology of wire electrospinning is presented for the manufacturing of air-permeable CO2-capturing membranes, easily transferable to industrial production lines. The design of the chemically-modified polyurethane nanofiber membranes for CO2 capture was based on a combination of molecular modeling and technological experiments using one-step electrospinning (i.e., a modifying agent dissolved directly in a spinning solution). Polyurethane (PUR Larithane), chemically modified by TETA/TEPA amines, was used in the present study for the membrane design. Special attention was paid to two key parameters significant for the design of the functional unit, i.e., the CO2 sorption capacity and air permeability which depended on the amine concentration. The optimal combination of these parameters was found for the PUR/TEPA membrane (5 wt.% of TEPA in spinning solution): the sorption capacity was 13.97 cm(3)/g with an air permeability of 0.020 m/s. Molecular modeling proved to be a valuable tool that helped to clarify, at the molecular level, the structure of chemically-modified nanofibrous membranes.Web of Science1011art. no. 10

Physiological and pathological factors affecting absorption of drugs

Absorption of drugs from the gastrointestinal tract after oral administration is a key pharmacokinetic process co-determining the subsequent pharmacodynamic response of the organism and therapeutic efficacy. This dissertation thesis is devoted to the study of factors that influence this parameter. Special emphasis is placed on the study of lymphatic absorption, i.e. the rate of absorption of the active substance via the intestinal lymphatic system. A number of in vivo studies have been carried out in laboratory rats. Pharmacokinetic studies have been performed by means of regular blood sampling from vascular catheters after oral administration of the drug. Lymphatic absorption was investigated in an anaesthetized mesenteric lymphatic duct cannulated rat model. Modern drugs were tested that were incorporated into innovative dosage forms by collaborating chemical and technological institutions. Abiraterone acetate, a lipophilic agent used in the therapy of prostate cancer, was well absorbed from the gastrointestinal tract after administration in the form of oil marbles. This technology also succeeded in reducing the otherwise very significant positive food-effect. Abiraterone acetate was not absorbed to any significant extent via the intestinal lymphatic system. In contrast, lymphatic absorption of..

Emergence of Fungicide Sensitivity in Leptosphaeria maculans Isolates Collected from the Czech Republic to DMI Fungicides

In the Czech Republic, demethylation inhibitors (DMIs) are used both as fungicides in controlling phoma stem canker and as growth regulators. This heavy use can result in the development of resistant isolates. A total of 45 and 286 Leptosphaeria maculans isolates were tested in vitro, using the mycelial growth and microtiter plate assays, respectively. The objective was to determine the sensitivity of L. maculans isolates collected in the Czech Republic to the fungicides tetraconazole, metconazole, and prochloraz. The mean EC50 values with the mycelial growth plate method were 1.33, 0.78, and 0.40 µg mL−1 for tetraconazole, metconazole, and prochloraz, respectively. The mean EC50 values for the microtiter plate assay were 3.01, 0.44, and 0.19 µg mL−1 for tetraconazole, metconazole, and prochloraz, respectively. All three fungicides also had high variation factors that may be due to inserts in the ERG11 promoter region. In addition, cross sensitivity among the three fungicides was observed. Overall, the high variation factors and the PCR (polymerase chain reaction) results observed in this study could signify the presence of resistant isolates in L. maculans Czech populations, especially in isolates tested for sensitivity to tetraconazole

Emergence of Fungicide Sensitivity in <i>Leptosphaeria maculans</i> Isolates Collected from the Czech Republic to DMI Fungicides

In the Czech Republic, demethylation inhibitors (DMIs) are used both as fungicides in controlling phoma stem canker and as growth regulators. This heavy use can result in the development of resistant isolates. A total of 45 and 286 Leptosphaeria maculans isolates were tested in vitro, using the mycelial growth and microtiter plate assays, respectively. The objective was to determine the sensitivity of L. maculans isolates collected in the Czech Republic to the fungicides tetraconazole, metconazole, and prochloraz. The mean EC50 values with the mycelial growth plate method were 1.33, 0.78, and 0.40 µg mL−1 for tetraconazole, metconazole, and prochloraz, respectively. The mean EC50 values for the microtiter plate assay were 3.01, 0.44, and 0.19 µg mL−1 for tetraconazole, metconazole, and prochloraz, respectively. All three fungicides also had high variation factors that may be due to inserts in the ERG11 promoter region. In addition, cross sensitivity among the three fungicides was observed. Overall, the high variation factors and the PCR (polymerase chain reaction) results observed in this study could signify the presence of resistant isolates in L. maculans Czech populations, especially in isolates tested for sensitivity to tetraconazole

Significance of Sexual Reproduction of Phytophthora infestans in the Czech Republic

A total of 187 naturally late blight‑diseased potato leaves were sampled from 31 sites and five regions of the Czech Republic during the growing season in 2012–2014 and 2016 and examined microscopically for the ability of Phytophthora infestans to produce oospores in infected leaves under field conditions. Although the occurrence of the A1 and A2 mating types required for sexual reproduction of P. infestans was previously confirmed in the Czech Republic, no oospores were detected in this study. To study the effect of temperature on the survival of oospores produced from crosses of three pairs of P. infestans isolates, oospores in leaf discs and agar were exposed to temperatures ranging from –24 to 10 °C and then evaluated for viability with the plasmolysis test. Oospore viability ranged from 13.02 to 63.90 % and from 7.77 to 63.37 % for oospores produced in agar and leaf discs, respectively, with the highest frequencies of viable oospores occurring at 4 and 10 °C. To determine whether oospores may survive under field conditions, agar plates with oospores were buried in soil in Prague‑Suchdol and Svitavy for seven months during the overwintering period (October–May) in 2011–2015. There were statistically significant differences in oospore viability examined by the plasmolysis test between the localities, and oospore viability ranged from 29 to 43 % and from 15 to 44 % in Prague‑Suchdol and Svitavy, respectively

Molecular evidence for the polyphyletic origin of low pH adaptation in the genus Klebsormidium (Klebsormidiophyceae, Streptophyta)

Background and aims – Algae living in low pH environments have been the subject of numerous studies, but their phylogenetic relationships with relatives found in non-acidic habitats are poorly known. In the present study we analyzed the morphology and phylogeny of acid-adapted strains of Klebsormidium, a genus of filamentous green algae frequently present in low pH environments. Methods – Eighteen strains of Klebsormidium were collected from from low pH habitats in Europe and U.S.A., mainly from terrestrial sites affected directly or indirectly by carbon mining activities. These algae were isolated in culture and their phylogenetic relationships were studied using rbc L and ITS rDNA sequence data in a concatenated dataset. Key results – In the molecular phylogeny the strains of Klebsormidium living in low pH habitats formed a polyphyletic assemblage. They were representative of sixteen lineages and corresponded morphologically to six species ( K. crenulatum, K. elegans, K. flaccidum, K. fluitans, K. nitens, K. scopulinum ), with the exception of four strains for which an unambiguous identification was not possible. Conclusions – The genus Klebsormidium is a group of morphologically and physiologically dynamic algae in which the capacity of adaptation to low pH conditions has been developed multiple times independently. Extreme acidophilic populations probably originate from populations of various species growing locally when strongly acidic habitats become available. For the acid-adapted lineages of Klebsormidium examined here the current known distribution is geographically restricted, with the exception of a lineage containing strains from Czech Republic, New Zealand and Ohio