Search

The growth and physiology of soil microorganisms, which play vital roles in biogeochemical cycling, are shaped by both current and historical soil environmental conditions. Here, we developed and applied a genome-resolved metagenomic implementation of quantitative stable isotope probing (qSIP) with an H 2 18 O labeling experiment to identify actively growing soil microorganisms and their genomic capacities. qSIP enabled measurement of taxon-specific growth because isotopic incorporation into microbial DNA requires production of new genome copies. We studied three Mediterranean grassland soils across a rainfall gradient to evaluate the hypothesis that historic precipitation levels are an important factor controlling trait selection. We used qSIP-informed genome-resolved metagenomics to resolve the active subset of soil community members and identify their characteristic ecophysiological traits. Higher year-round precipitation levels correlated with higher activity and growth rates of flagellar motile microorganisms. In addition to heavily isotopically labeled bacteria, we identified abundant isotope-labeled phages, suggesting phage-induced cell lysis likely contributed to necromass production at all three sites. Further, there was a positive correlation between phage activity and the activity of putative phage hosts. Contrary to our expectations, the capacity to decompose the diverse complex carbohydrates common in soil organic matter or oxidize methanol and carbon monoxide were broadly distributed across active and inactive bacteria in all three soils, implying that these traits are not highly selected for by historical precipitation. IMPORTANCE Soil moisture is a critical factor that strongly shapes the lifestyle of soil organisms by changing access to nutrients, controlling oxygen diffusion, and regulating the potential for mobility. We identified active microorganisms in three grassland soils with similar mineral contexts, yet different historic rainfall inputs, by adding water labeled with a stable isotope and tracking that isotope in DNA of growing microbes. By examining the genomes of active and inactive microorganisms, we identified functions that are enriched in growing organisms, and showed that different functions were selected for in different soils. Wetter soil had higher activity of motile organisms, but activity of pathways for degradation of soil organic carbon compounds, including simple carbon substrates, were comparable for all three soils. We identified many labeled, and thus active bacteriophages (viruses that infect bacteria), implying that the cells they killed contributed to soil organic matter. The activity of these bacteriophages was significantly correlated with activity of their hosts.

Predation structures food webs, influences energy flow, and alters rates and pathways of nutrient cycling through ecosystems, effects that are well documented for macroscopic predators. In the microbial world, predatory bacteria are common, yet little is known about their rates of growth and roles in energy flows through microbial food webs, in part because these are difficult to quantify. Here, we show that growth and carbon uptake were higher in predatory bacteria compared to nonpredatory bacteria, a finding across 15 sites, synthesizing 82 experiments and over 100,000 taxon-specific measurements of element flow into newly synthesized bacterial DNA. Obligate predatory bacteria grew 36% faster and assimilated carbon at rates 211% higher than nonpredatory bacteria. These differences were less pronounced for facultative predators (6% higher growth rates, 17% higher carbon assimilation rates), though high growth and carbon assimilation rates were observed for some facultative predators, such as members of the genera Lysobacter and Cytophaga , both capable of gliding motility and wolf-pack hunting behavior. Added carbon substrates disproportionately stimulated growth of obligate predators, with responses 63% higher than those of nonpredators for the Bdellovibrionales and 81% higher for the Vampirovibrionales , whereas responses of facultative predators to substrate addition were no different from those of nonpredators. This finding supports the ecological theory that higher productivity increases predator control of lower trophic levels. These findings also indicate that the functional significance of bacterial predators increases with energy flow and that predatory bacteria influence element flow through microbial food webs. IMPORTANCE The word "predator" may conjure images of leopards killing and eating impala on the African savannah or of great white sharks attacking elephant seals off the coast of California. But microorganisms are also predators, including bacteria that kill and eat other bacteria. While predatory bacteria have been found in many environments, it has been challenging to document their importance in nature. This study quantified the growth of predatory and nonpredatory bacteria in soils (and one stream) by tracking isotopically labeled substrates into newly synthesized DNA. Predatory bacteria were more active than nonpredators, and obligate predators, such as Bdellovibrionales and Vampirovibrionales , increased in growth rate in response to added substrates at the base of the food chain, strong evidence of trophic control. This work provides quantitative measures of predator activity and suggests that predatory bacteria-along with protists, nematodes, and phages-are active and important in microbial food webs., (Copyright © 2021 Hungate et al.)

Thanks to multi-compartment systems it is possible to modify drug release. Two types of mini tablets containing 12.5 mg of ketoprofen were made: mini tablets of immediate (IR) and sustained (SR) release. Some of the tablets of immediate release were coated with an enteric coating, thereby obtaining a delayed release effect (IRc). For each tablet type, release profiles were tested in three media: 0.1 M HCl, phosphate buffer pH 4.5 and phosphate buffer pH 6.8. Based on the obtained results, three appropriate multi-compartment models have been constructed and tested. The factor limiting the amount of available ketoprofen at the absorption place is pH of the environment. It was observed that the increase in pH caused the increase of ketoprofen solubility. Constructed multi-compartment systems allowed to change the composition and the dose of medicinal substances easily. Thanks to this it is possible to adjust the release profile of the active substance to the individual patient, which meets the expectations of personalized medicine.

In the recent years a significant development of investigations with regard to bioavailability of ocular drugs has been noticed. The corneal epithelial barrier is the main pathway for ocular penetration of topically applied ophthalmic drugs into the anterior chamber. To work out an in vitro model of bovine corneal epithelial primary cultures and exercise it for permeability research with lipophilic and hydrophilic markers, permeability coefficients estimation of the 6-carboxyfluorescein and rhodamin B was made. The corneal epithelial cultures of the 3th or 4th passage were chosen for layered culture with inserts based on the liquid-liquid interface (for the first week) and the air-liquid interface (for the two following weeks). On the 7th, 12th, 18th, 21st experiment day TER values, and on the 21st day drug permeability coefficients, were determined. The mean TER values of the 7th, 12th, 18th, 21st day of corneal epithelial culture were: 122.14, 155.14, 198.43 and; 247.43 Wcm2, respectively. The mean values of permeability coefficients on the 21st day of culture for 6-carboxyfluorescein and rhodamin B were 3.87 +/-0.10 x 10(-6)cm/s and 3.65 +/- 0.06 x 10(-6)cm/s, respectively. We state that the in vitro bovine corneal epithelial primary culture model is useful for ocular studies.

Objective: The aim of the presented comparative study was to evaluate the bioavailability of clopidogrel (CAS 113665-84-2) formulations containing clopidogrel bisulfate (CAS 135046-48-9, CBS) 75 mg based on the parent compound (CBS) and its metabolite SR 26334 - clopidogrel carboxylic acid (CAS 144457-28-3, CCA) determination., Methods: This paper presents the results of a comparative, randomized, two-way cross-over study on 48 healthy male volunteers assessing the bioequivalence of two products of clopidogrel 75 mg in form of film-coated tablets. In each of the two periods, separated by a 7-day washout period, a single dose of 150 mg (2 x 75 mg) of test and reference preparations was administered under fasting condition. Nineteen blood samples for determination of CBS and CCA were collected up to 48 h post dose. The CBS and CCA concentrations were quantified by a selective ultra performance liquid chromatographic-tandem mass spectrometric (UPLC-MS/MS) method. Pharmacokinetic parameters such as AUCinf, AUCt, Cmax, tmax, t1/2 were estimated using a non-compartmental model. Bioequivalence evaluation and calculation of CI were performed for clopidogrel and its metabolite by two one-sided t-test procedures by Schuirmann., Results: In case of CCA the values of pharmacokinetic parameters were similar for the two products (test vs reference): AUCinf: 15773 vs. 15691 ng x h/mL, AUCt: 15,462 vs. 15,315 ng x h/mL, Cmax: 4919 vs. 4699 ng/mL, tmax: 0.84 vs. 0.93 h, t1/2: 7.92 vs. 8.41 h. Points of estimation of the ratios test/reference were near to 100% and CI in ranges 80-125% were fulfilled for all tested parameters. Pharmacokinetic parameters values of CBS were: AUCinf: 1.96 vs. 1.84 ng x h/mL (test vs reference), AUCt: 1.91 vs. 1.81 ng x h/mL, Cmax, 1.44 vs. 1.52 ng/mL, tmax: 0.90 vs. 0.99 h, t1/2: 0.74 vs. 0.57 h. The parametric 90%-confidence interval (CI) was in the range of 80-125% for AUCt ratio and AUCinf ratio. The CI range of Cmax fulfilled the widened range of 75-133% (according to the study protocol). Unfortunately, the very high variability of pharmacokinetic parameters (over 50%) contributed to low power of the test., Conclusions: Measurement of CBS concentrations should not be a reliable one for the bioequivalence assessment, due to very low concentrations, very small and variable values of AUC and high intra-subject variability. Thus, bioequivalence evaluation should be based on CCA determination. In the presented study evaluation based on CCA unequivocally and with the proper power confirmed the bioequivalence between the investigated clopidogrel products.

Purpose: Evaluation of antioxidants: selenium and vitamin E efficacy in the treatment of experimental corneal lesion., Material and Methods: Solution of selenium in 0.9% NaCl, concentration 0.01 g/L, to which vitamin E was added to obtain suspension of 2.5 g/L was used in 9 rabbits. The cornea was damaged by removing the epithelium from the central area of 7 mm diameter. To the right eye selenium solution with vitamin E was instilled., Results: In two eyes in which antioxidants were used evident prompt healing of corneal ulceration was noticed. Mean lesion diameter in eyes treated with antioxidants was: on 1st day 5.44 mm, in 2nd day 1.61 mm and on the 3rd day 0.33 mm. In control eyes diameters were: 6.67 mm, 2.28 mm and 0.56 mm, respectively., Conclusions: Solution used in our study was tolerated very well. Faster healing process was noticed in eyes where antioxidants were used.

Investigations were performed in rabbits which were given gentamycin intramuscularly and subconjunctivally. After subconjunctival application gentamycin passes quickly into the eye and its therapeutical level persists up to 1 hour. After intramuscular injection gentamycin is passing slower into the aqueous but persists there longer (the therapeutical level--up to 5.5 hours).

There are following forms of the most frequently used ocular therapeutics: eye drops, ointments and inserts. In dependence on the physico-chemical properties of the therapeutical substance and the kind of disease one has to formulate the form of the drug in the manner to obtain its maximal bioavailability. By increasing their viscosity one can keep the watery solutions in the conjunctival sac for around 60 min. The time of the contact of the drug given in the form of suspension is limited mainly by the viscosity of the solution and the size of the molecules suspended in it. The ointments stay on the surface of the eye up to 2 hours. The ocular inserts secure a steady flow of the therapeutical substance up to 7 days. The compounds penetrate to the anterior chamber aqueous mainly through the cornea. Therefore the physiological factors of the lacrimal fluid, the properties of the cornea are influencing the penetration of the corneo-chamber barrier by the therapeutical substance.

The purpose of this study was to investigate the pharmacokinetics of carbamazepine at steady state, after multiple doses in patients with elevated serum cholesterol levels. Twelve patients participated in the investigation; patients were divided into two groups according to their total serum cholesterol levels. Each patient received multiple doses of carbamazepine 600 mg po once per day. Blood samples were collected and analyzed for carbamazepine by gas-liquid chromatography. The clearance concept was used to describe the pharmacokinetic behavior of carbamazepine in high and low cholesterol patients. The area under the plasma concentration-time curve was determined by the trapezoidal rule method. This value was used to determine the oral dose clearance. In this study, the authors found that the elevated serum cholesterol and elevated total lipids cause a decrease in drug concentration. The significantly higher values of the total body clearance of carbamazepine, obtained in patients with elevated serum cholesterol levels, may have significance in clinical practice.