Biodegradable Injectable In Situ Implants and Microparticles for Sustained Release of Montelukast: In Vitro Release,Pharmacokinetics, and Stability

The objective of this study was to investigate the sustained release of a hydrophilic drug, montelukast (MK), from two biodegradable polymeric drug delivery systems, in situ implant (ISI) and in situ microparticles (ISM). N-Methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO), triacetin, and ethyl acetate were selected as solvents. The release of 10% (w/v) MK from both systems containing poly-lactic-co-glycolic acid (PLGA) as the biodegradable polymer was compared. Upon contact with the aqueous medium, the PLGA in ISI and ISM systems solidified resulting in implants and microparticles, respectively. The in vitro drug release from the ISI system showed marked difference from miscible solvents (NMP and DMSO) than the partially miscible ones (triacetin and ethyl acetate), and the drug release decreased with increased PLGA concentration. In the ISM system, the initial in vitro drug release decreased with decreased ratio of polymer phase to external oil phase. In vivo studies in rats showed that ISM had slower drug release than the drug release from ISI. Also, the ISM system when compared to ISI system had significantly reduced initial burst effect. In vitro as well as the in vivo studies for both ISI and ISM systems showed sustained release of MK. The ISM system is suitable for sustained release of MK over 4-week period with a lower initial burst compared to the ISI system. Stability studies of the ISI and ISM formulations showed that MK is stable in the formulations stored at 4°C for more than 2 years.     

Intrastriatal Administration of Methylmercury Increases In Vivo Dopamine Release

Mercury is a neurotoxin that exists in a number of physical and chemical forms, producing different effects in the brain. In the present work, we have studied the effects of intrastriatal administration of different doses (40 M, 400 M, and 4 mM) of organic mercury (methylmercury, MeHg) on the dopaminergic system of rat striatum, in conscious and freely-moving animals, using microdialysis coupled to Liquid Chromatography. In previous works, we have discussed the effects of chronic and acute administration of MeHg on striatal dopaminergic system assessing changes in both release and metabolism of striatal dopamine (DA). In the present study we report that the intrastriatal administration of different doses of MeHg (40 M, 400 M, and 4 mM) produced significant increases (907 ± 31%, 2324 ± 156%, and 9032 ± 70% of basal levels, respectively for the different doses) in DA release from rat striatal tissue associated with significant decreases in extracellular levels of its main metabolites dihydroxyphenylacetic acid (DOPAC) and homovallinic acid (HVA) using the dose of 4 mM MeHg (35 ± 3% and 48 ± 1%, respectively), whereas non-significant changes in metabolite levels were observed with the doses of 40 M and 400 M MeHg. We explain these effects as a result of stimulated DA release and/or decreased DA intraneuronal degradation.     

Comparison of In Situ and In Vitro Rates of Methane Release in Freshwater Sediments

Anaerobic lake sediment incubated in vitro was investigated for its ability to mimic natural in situ sediment activities, using rate of methane production for the comparison. Two lakes with different rates and seasonal patterns of methanogenic activity were compared. There was good agreement (at the 97.5% confidence level) between rates of in situ methane release and initial (lasting an average of 120 h) rates of production measured in vitro in surface (0- to 3-cm) sediment. Evidence from this study, and others, indicated that it is the in situ surface sediment methane production which is primarily responsible for maintaining in situ methane release, and thus the above agreement was what was expected if surface in situ activity was maintained in vitro. When deeper sediment was investigated, however, the sum of in vitro rates from 0 to 20 cm (measured in 1.5- to 3-cm intervals) was much higher than in situ release rates and would have resulted in an impossibly high volume of gas. The extra gas could not have been stored within the sediments. We conclude that the in situ methanogenic activity of the 0- to 3-cm anaerobic surface sediments could be preserved during removal and laboratory incubation. However, similar treatment of deeper sediment appeared to stimulate methanogenic activity.     

Design of Methylprednisolone Biodegradable Microspheres Intended for Intra-articular Administration

This study aimed to design methyprednisolone (MP)-loaded poly(d,l lactide-co-glycolide) (PLGA) microspheres (MS) intended for intra-articular administration. MP was encapsulated in four different types of PLGA by using an S/O/W technique. The effects of β-irradiation at the dose of 25 kGy were evaluated on the chemical and physicochemical properties of MS and the drug release profiles. The S/O/W technique with hydroxypropylmethylcellulose (HPMC) as surfactant allowed obtaining MS in the tolerability size (7–50 μm) for intra-articular administration. The MP encapsulation efficiency ranged 56–60%. HPMC traces were evidenced in the loaded and placebo MS by attenuated total reflectance Fourier transform infrared spectroscopy. MS made of the capped PLGA DL5050 2M (MS 2M) and uncapped PLGA DL5050 3A (MS 3A) prolonged the release of MP over a 2- to 3-month period with a triphasic (burst release–dormant period–second release pulse) and biphasic release pattern, respectively. The β-irradiation did not significantly alter the morphology, chemical, and physicochemical properties of MS. The only variation was evidenced in the drug release for MS 2M in term of shorting of the dormant period. The minimal variations in the properties of irradiated PLGA MS, which are in disagreement with literature data, may be attributed to a radioprotecting effect exerted by HPMC.     

A Long-Term Field Study of In Situ Bioremediation in a Fractured Conglomerate Trichloroethene Source Zone

ABSTRACT An 8-year bioremediation field study was conducted in a trichloroethene (TCE)-contaminated, highly indurated (i.e., hard), recharge-limited (i.e., contains little water) conglomerate where common remediation strategies, such as groundwater recirculation and direct push installation of a large well network, could not be used. A tracer test using isotopically distinct water from the Hetch Hetchy Reservoir indicated that remediation fluids mainly flowed through fractures and sand lenses in the conglomerate. This was confirmed during in situ bioremediation of the site, in which Dehalococcoides (from a bioaugmentation culture) and volatile fatty acids (from injection of lactate) were the most accurate indicators of transport between wells. Some contaminants were also displaced out of the area due to injection of tracer water. Despite these difficulties, dissolved contaminant mass decreased by an estimated 80% by the end of the test, reaching the lowest values ever recorded at this site. Furthermore, the persistence of ethene 4 years after bioaugmentation suggests that the dechlorinating capacity of the remaining microbial community is comparable to the matrix diffusion of TCE into the dissolved phase.     

Studies on Mefenamic Acid Microparticles: Formulation, In Vitro Release, and In Situ Studies in Rats

In this study, we investigated the in vitro characteristics of mefenamic acid (MA) microparticles as well as their effects on DNA damage. MA-loaded chitosan and alginate beads were prepared by the ionotropic gelation process. Microsponges containing MA and Eudragit RS 100 were prepared by quasi-emulsion solvent diffusion method. The microparticles were characterized in terms of particle size, surface morphology, encapsulation efficiency, and in vitro release profiles. Most of the formulation variables manifested an influence on the physical characteristics of the microparticles at varying degrees. We also studied the effects of MA, MA-loaded microparticles, and three different polymers on rat brain cortex DNA damage. Our results showed that DNA damage was higher in MA-loaded Eudragit microsponges than MA-loaded biodegradable chitosan or alginate microparticles.     

In Situ Biodosimetric Experiment for Space Applications

This paper presents the principles and application of DNA based biological UV dosimeters, as developed by Research Group for Biophysics (RGB). These dosimeters are used for assessing the biological hazard of living systems on the Earth's surface and in different waters (rivers, lakes, seas, etc.). The UV dosimetry system has also been used in the space. In dosimeters a bacterial virus, bacteriophage T7 and polycrystalline uracil thin layers have been used as biological detectors. On the Earth's surface the UV radiation induces dimer formation in phage T7 and in the uracil detector, which was evaluated by loss of viability of the phage particles and by the decrease of the characteristic optical density (OD) of uracil thin layers. Recently the development of human space activities has also increased the need to measure the biological effect of extraterrestrial solar radiation, too. The evaluation of the space samples occurred on ground, thus only the starting and the final state were taken into account. A new improved, automated method is presented below which makes data collection more efficient and also makes the dynamics of the process observable.     

Long-Term Preservation of Fungus Cultures with Liquid Nitrogen Refrigeration

A preservation technique was tested on 162 strains of culturally fastidious fungi sensitive to lyophilization, representing five classes. The results indicated that liquid nitrogen storage of frozen specimens may be used as an alternative to lyophilization for long-term preservation of stock cultures of fungi. The fungus was frozen in 10% (v/v) glycerol-water menstruum in heat-sealed ampoules. The cooling from ambient temperatures to -35 C was controlled at a rate of approximately 1 C per minute. Further cooling to the storage temperature of -165 to -196 C was uncontrolled and took place at an accelerated rate. Frozen ampoules were thawed in a water bath at 38 to 40 C. Viable and unmutated cultures were developed from reactivated specimens after storage for as long as 5 years.     

Liquid Crystalline Systems for Transdermal Delivery of Celecoxib: In Vitro Drug Release and Skin Permeation Studies

Liquid crystalline systems of monoolein/water could be a promising approach for the delivery of celecoxib (CXB) to the skin because these systems can sustain drug release, improve drug penetration into the skin layers and minimize side effects. This study evaluated the potential of these systems for the delivery of CXB into the skin based on in vitro drug release and skin permeation studies. The amount of CXB that permeated into and/or was retained in the skin was assayed using an HPLC method. Polarizing light microscopy studies showed that liquid crystalline systems of monoolein/water were formed in the presence of CXB, without any changes in the mesophases. The liquid crystalline systems decreased drug release when compared to control solution. Drug release was independent of the initial water content of the systems and CXB was released from cubic phase systems, irrespective of the initial water content. The systems released the CXB following zero-order release kinetics. In vitro drug permeation studies showed that cubic phase systems allowed drug permeation and retention in the skin layers. Cubic phase systems of monoolein/water may be promising vehicles for the delivery of CXB in/through the skin because it improved CXB skin permeation compared with the control solution.KEY WORDS: celecoxib, drug delivery systems, liquid crystalline system, monoolein, skin permeation     

Effect of Long-Term Treatment with Selective Monoamine Oxidase A and B Inhibitors on Dopamine Release from Rat Striatum In Vivo

Abstract: Acute inhibition of monoamine oxidase B (MAO-B) in the rat does not affect striatal dopamine (DA) metabolism, but chronic MAO-B inhibition with deprenyl has been reported to increase the release of striatal DA, as shown using in vitro techniques. To see whether chronic MAO-B inhibition also causes an increase in DA release in vivo, rats were treated for 21 days with either deprenyl (0.25 mg/kg), TVP-1012 [R(+)-N-propargyl-1-aminoindan mesylate; 0.05 mg/kg), an irreversible inhibitor of MAO-B that is not metabolized to amphetamines, clorgyline (0.2 mg/kg), or saline (all doses once daily by subcutaneous injection). Concentric 4-mm-long microdialysis probes were implanted in the left striatum under pentobarbital/chloral hydrate anesthesia on day 21, and microdialysate DA, 3,4-dihydroxyacetic acid (DOPAC), and 4-hydroxy-3-methoxyphenyl acetic acid (HVA) were determined in the conscious animals on day 22. Baseline levels of DA were as follows: control, 0.34 ± 0.04 (n = 13); deprenyl, 0.88 ± 0.10 (n = 8, p < 0.01); TVP-1012, 0.94 ± 0.20 (n = 7, p < 0.01); clorgyline, 0.90 ± 0.12 (n = 7, p < 0.01) pmol/20 min. Levels of DOPAC and HVA were reduced only in the clorgyline-treated group. The incremental release of DA induced by depolarizing concentration of K⁺ (100 mM bolus of KCl in perfusate) was significantly greater in clorgyline- and deprenyl-treated rats and elevated (nonsignificantly) in TVP-1012-treated rats. Chronic treatment with the MAO-B inhibitors reduced striatal MAO-B activity by 90%, with 15% (TVP-1012) or 40% (deprenyl) inhibition of MAO-A. Clorgyline inhibited MAO-A by 95%, with 30% inhibition of MAO-B. A single dose of deprenyl (0.25 mg/kg, 24 h before microdialysis) had no significant effect on striatal efflux of DA. The results show that DA metabolism was reduced only by clorgyline, whereas neuronal release of DA was enhanced by both MAO-A and MAO-B inhibitors on chronic administration. The enhanced DA release by chronic MAO-B inhibition does not appear to be dependent on production of amphetamine-like metabolites of the inhibitor. Possible mechanisms for the release-enhancing effect of the MAO-B inhibitors include elevation in levels of endogenous β-phenylethylamine, or an inhibition of DA reuptake, which develops only on chronic administration, because both deprenyl and TVP-1012 have only very weak effects on amine uptake in acute experiments.     

Comparison of the Long-Term Risks of Removal and In Situ Management of Contaminated Sediments in the Fox River

The long-term potential risks of environmental dredging vs. in situ contaminated sediment management practices are discussed and compared for the Lower Fox River, Wisconsin. The risks are identified as being largely associated with the residual sediment contamination associated with either approach. The integral of the surface area-weighted average contaminant concentration in surface sediment is proposed as a metric to compare these risks. Capping is shown to exhibit significantly reduced exposure and risk relative to the dredging scenarios, even if potential undetected erosion of 5% of the cap is considered. Even with the improbable event of undetected failure of 25% of the cap, the exposure and risk associated with capping is approximately equal to or below all dredging scenarios. A preference for dredging due to the perception that it eliminates the long-term risk of in situ capping is not supported by this analysis. Although strictly applicable only to the Lower Fox River, the results suggest sitespecific analyses must be conducted to determine which sediment management approaches minimize the potential for long-term exposure and risk.     

Active Sensing System with In Situ Adjustable Sensor Morphology

Background

Despite the widespread use of sensors in engineering systems like robots and automation systems, the common paradigm is to have fixed sensor morphology tailored to fulfill a specific application. On the other hand, robotic systems are expected to operate in ever more uncertain environments. In order to cope with the challenge, it is worthy of note that biological systems show the importance of suitable sensor morphology and active sensing capability to handle different kinds of sensing tasks with particular requirements.

Methodology

This paper presents a robotics active sensing system which is able to adjust its sensor morphology in situ in order to sense different physical quantities with desirable sensing characteristics. The approach taken is to use thermoplastic adhesive material, i.e. Hot Melt Adhesive (HMA). It will be shown that the thermoplastic and thermoadhesive nature of HMA enables the system to repeatedly fabricate, attach and detach mechanical structures with a variety of shape and size to the robot end effector for sensing purposes. Via active sensing capability, the robotic system utilizes the structure to physically probe an unknown target object with suitable motion and transduce the arising physical stimuli into information usable by a camera as its only built-in sensor.

Conclusions/Significance

The efficacy of the proposed system is verified based on two results. Firstly, it is confirmed that suitable sensor morphology and active sensing capability enables the system to sense different physical quantities, i.e. softness and temperature, with desirable sensing characteristics. Secondly, given tasks of discriminating two visually indistinguishable objects with respect to softness and temperature, it is confirmed that the proposed robotic system is able to autonomously accomplish them. The way the results motivate new research directions which focus on in situ adjustment of sensor morphology will also be discussed.     

Improved In Situ Hybridization Efficiency with Locked-Nucleic-Acid-Incorporated DNA Probes

Low signal intensity due to poor probe hybridization efficiency is one of the major drawbacks of rRNA-targeted in situ hybridization. There are two major factors affecting the hybridization efficiency: probe accessibility and affinity to the targeted rRNA molecules. In this study, we demonstrate remarkable improvement in in situ hybridization efficiency by applying locked-nucleic-acid (LNA)-incorporated oligodeoxynucleotide probes (LNA/DNA probes) without compromising specificity. Fluorescently labeled LNA/DNA probes with two to four LNA substitutions exhibited strong fluorescence intensities equal to or greater than that of probe Eub338, although these probes did not show bright signals when they were synthesized as DNA probes; for example, the fluorescence intensity of probe Eco468 increased by 22-fold after three LNA bases were substituted for DNA bases. Dissociation profiles of the probes revealed that the dissociation temperature was directly related to the number of LNA substitutions and the fluorescence intensity. These results suggest that the introduction of LNA residues in DNA probes will be a useful approach for effectively enhancing probe hybridization efficiency.