Slow Release Phase Research Articles

Kitchen Waste Digestate and Digestate Biochar Fertilizer for Turfgrass Management and Nutrient Leaching

Slow-release fertilizer is generally used in turfgrass management to maintain quality turf without inducing excess vertical growth, to avoid frequent mowing. This study was designed to verify whether kitchen waste digestate and digestate biochar could serve as slow-release fertilizers to promote turf quality and reduce nutrient leaching risk in two turfgrass species over two years in controlled pot experiments. The results showed that the nutrient release of granular fertilizers made from kitchen waste digestate and digestate biochar was a two-phase process (an initial rapid phase, followed by a slow-release phase). The kitchen waste digestate showed higher nitrogen and phosphorus release ratios than the biochar and sheep manure. Compared to the reference sheep manure, fertilization with kitchen waste digestate and biochar increased the leaf chlorophyll content by 48.6% and 27.9%, and reduced senescent leaves by 15.6% and 11.1%, respectively, at 23 d after fertilization, leading to higher turf quality. Fertilization with kitchen waste digestate biochar significantly reduced the nutrient leaching risk compared to fertilization with kitchen waste digestate and sheep manure. Our results demonstrated the potential of reusing kitchen waste digestate and digestate biochar as slow-release fertilizers for promoting turf quality in turfgrass management.

Biofilm Formation is Durably Prevented on Pre-Fabricated Antibiotic Cement Spacers Compared to Cobalt Chrome and Polyethylene

BackgroundA 2-stage revision remains the standard for managing chronic periprosthetic joint infection. Despite multiple spacer options, whether a particular one better resists biofilm formation remains unclear. Prefabricated polymethylmethacrylate (PMMA) articulating spacers containing antibiotics and a proprietary pore structure were developed to increase antibiotic elution characterized by a rapid burst phase for the initial one to two days and an extended slow-release phase for > 28 days. This in vitro study determined whether biofilm formation is prevented during the initial rapid burst phase and/or the slow-release phase. MethodsS. aureus-Xen36 was incubated in 1.5 mL of Luria-Bertani broth with PMMA discs with the proprietary pore structure either with or without gentamycin and vancomycin or with ‘Hoffman style’ positive-control discs (ultra-high molecular weight polyethylene or cobalt-chrome). Nonadherent bacteria were removed by three phosphate buffered saline rinses every 20 to 24 hours. Planktonic bacterial growth in the culture broth and biofilm formation on the discs were measured by colony forming unit (CFU) counting and resazurin reduction assays. Experiments were repeated > four times. ResultsNo detectable planktonic bacterial growth or biofilm formation occurred in cultures containing PMMA with antibiotics (≤ 15 CFUs/disc), whereas biofilms formed on PMMA without antibiotics, ultra-high molecular weight polyethylene, and cobalt-chrome (1 × 107 to 4 × 108 CFUs/disc, P < 0.0001). Biofilm formation was confirmed by a 100-fold decrease in sensitivity to vancomycin. To determine whether the antibiotic slow-release phase is sufficient to block biofilm formation, PMMA discs with antibiotics were preeluted for 14 days with multiple saline changes prior to bacterial inoculation. After antibiotic elution, still no detectable biofilms formed on PMMA discs with antibiotics (≤ 15 CFUs/disc, P < 0.0001). ConclusionsAntibiotic release during both the initial and slow-release phases prevented biofilm formation on PMMA with the proprietary pore structure. This may translate into improved infection eradication rates clinically.

Direct drug milling in organic PLGA solution facilitates the encapsulation of nanosized drug into PLGA microparticles

The objective of this study was to prepare poly(lactide-co-glycolide) (PLGA) microparticles loaded with nanosized drug by combining non-aqueous wet bead milling and microencapsulation. 200–300 nm dexamethasone, hydrocortisone and dexamethasone sodium phosphate nanosuspensions were successfully prepared by wet bead milling the drug in dichloromethane using PLGA as a stabilizer. PLGA microparticles loaded with nanosized drugs were then prepared by a solid-in-oil-in-water (S/O/W) solvent evaporation method or solid-in-oil-in-oil (S/O/O) organic phase separation method. The microparticles were characterized by laser diffraction (LD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD) and in vitro drug release. The nanosized drugs were homogeneously distributed within the microparticle matrix and remained crystalline, however, with a decrease in crystallinity. High drug encapsulation efficiencies >80 % were achieved at theoretical drug loadings between 5 and 30 %. Drug release profiles could be controlled by varying PLGA grades/blends, microparticle size and drug loadings. Quasi-linear release profiles without the PLGA-typical slow release phase were achieved with PLGA encapsulated nanosized drug.

β-tricalcium phosphate/gelatin composite scaffolds incorporated with gentamycin-loaded chitosan microspheres for infected bone defect treatment.

The repair of infected bone defects remains a clinical challenge. Staphylococcus aureus is a common pathogenic micro-organism associated with such infections. Gentamycin (GM) is a broad spectrum antibiotic that can kill S. aureus in a dose-dependent manner. However, the systemic administration of antibiotics may lead to drug resistance and gut dysbiosis. In this work, we constructed β-tricalcium phosphate/gelatin composite scaffolds incorporated with gentamycin-loaded chitosan microspheres (CMs(GM)-β-TCP/gelatin composite scaffolds), which helped optimize the local GM release in the infected defect areas and enhance bone regeneration. The cumulative release curves showed that both microspheres and composite scaffolds reached a sustained slow-release phase after the initial rapid release, and the latter further stabilized the initial drug release rate. The release curve of CMs(GM)-β-TCP/gelatin composite scaffolds reached a plateau after 24 h, and the cumulative release reached 41.86% during this period. Moreover, the combination of β-TCP and gelatin mimicked bone composition and were able to provide the requisite mechanical strength (0.82 ± 0.05 MPa) during the first phase of bone generation. The inner structure of the scaffold was arranged in the shape of interconnected pores, and presented a porosity level of 16%. The apertures were uniform in size, which was beneficial for cell proliferation and material transportation. Macroscopic observation and histological analysis showed that CMs(GM)-β-TCP/gelatin composite scaffolds fused with bone tissues, and new tissues were formed in defect areas without any infection. This new composite scaffold may be a promising repair material for treating infected bone defects.

The reciprocal interaction between fluoride release of glass ionomers and acid production of Streptococcus mutans biofilm

ABSTRACT Objectives The aim of this study was to demonstrate the mode of action of glass ionomers (G-Is) against cariogenic biofilms in the slow fluoride release phase by analyzing the reciprocal interaction between fluoride release from G-Is and acid production of Streptococcus mutans biofilm. Methods G-Is discs in the slow fluoride release phase were prepared and 51 h-old S. mutans biofilms were formed on these discs. The interrelationship between the acid production of the biofilm and the fluoride release of the G-Is discs was investigated by analyzing both factors simultaneously during the biofilm formation period. The composition of the 51 h-old biofilms was then examined using microbiological, biochemical, and confocal laser scanning microscopic methods. Results Acid production by the cariogenic biofilm, particularly at < pH 5, promotes G-Is fluoride release. Conversely, G-Is fluoride release inhibits the acid production of the cariogenic biofilm. This reciprocal interaction results in the reduction of virulence such as extracellular polysaccharides formation and cariogenic biofilm bio-mass, which may reduce the potential of secondary caries development around G-Is. Conclusions These results suggest that G-Is may play a role in preventing the development of secondary caries during the slow fluoride release phase.

The Effect of Governmental Health Measures on Public Behaviour During the COVID-19 Pandemic Outbreak.

The coronavirus disease 2019 (COVID-19) pandemic resulted in radical changes in many aspects of life. To deal with this, each country has implemented continuous health measures from the beginning of the outbreak. Discovering how governmental actions impacted public behaviour during the outbreak stage is the purpose of this study. This study uses a hybrid large-scale data visualisation method to analyse public behaviour (epidemic concerns, self-protection, and mobility trends), using the data provided by multiple authorities. Meanwhile, a content analysis method is used to qualitatively code the health measures of three countries with severe early epidemic outbreaks from different continents, namely China, Italy, and the United States. Eight dimensions are coded to rate the mobility restrictions implemented in the above countries. (1) Governmental measures did not immediately persuade the public to change their behaviours during the COVID-19 epidemic. Instead, the public behaviour proceeded in a three-phase rule, which is typically witnessed in an epidemic outbreak, namely the wait-and-see phase, the surge phase and the slow-release phase. (2) The strictness of the mobility restrictions of the three countries can be ranked as follows: Hubei Province in China (with an average score of 8.5 out of 10), Lombardy in Italy (7.125), and New York State in the United States (5.375). Strict mobility restrictions are more likely to cause a surge of population outflow from the epidemic area in the short term, whereas the effect of mobility restrictions is positively related to the stringency of policies in the long term. The public showed generally lawful behaviour during regional epidemic outbreaks and blockades. Meanwhile public behaviour was deeply affected by the actions of local governments, rather than the global pandemic situation. The contextual differences between the various countries are important factors that influence the effects of the different governments' health measures.

Effects of repetitive submergence on the accumulation and release of nutrient elements in Pinus elliottii seedlings

Pinus elliottii is an evergreen coniferous tree. It is considered a potential species for ecological restoration in the Three Gorges Reservoir Area (TGRA). To classify the effects of different degrees of flooding stress in winter on nutrient accumulation in Pinus elliottii after experiencing early drought stress in summer, simulated water treatments of deep submergence (DS) and moderate submergence (MS) were imposed after the summer drought period. The results indicated that the survival rate of seedlings was 95.3%, and the accumulation trend of the flooded plants was rapid at an average rate of 1.99 ± 0.33% in the early stage of flooding (stage I: 0-7 days), a rapid release rate in the second stage (stage II: 7-60 days), and an average rate of only 0.07 ± 0.04% in the later stage (stage III: 60-150 days). After 150 days of flooding, the leaves of Pinus elliottii released an average of 7.156 ± 0.4 g kg-1 of organic carbon, 8.839 ± 0.6 g kg-1 of nitrogen, 0.781 ± 0.1 g kg-1 of phosphorus, and 2.985 ± 0.3 g kg-1 of potassium of macroelement content, and an average of 0.201 ± 0.03 g kg-1 manganese, 0.147 ± 0.04 g kg-1 iron, 0.002 g kg-1 copper, and 0.023 g kg-1 of zinc of microelement contents. Our results also demonstrated that after 150 days of flooding, the C/N, N/P, and C/P ratios of the nutrient element content of Pinus elliottii in the water-level fluctuation zone of the TGRA were 0.810%, 11.32%, and 9.16%, respectively. The absorption and release of nutrients under water flooding are generally divided into three stages: first, the early storage stage (the first stage: 0 to 7 days, optional), then the rapid release (the second stage: 7 to 60 days), and the later stage slow release phase (third stage: 60 to 150 days). Water flooding reduced the contents of C, N, P, and K and affected the absorption of nutrient elements in the plant. At the same time, soluble Mn2 + and Fe2 + over absorbed during flooding could cause toxicity to leaf tissues. At the same time, Pinus elliottii selected to reduce Cu in leaves to ensure that the root has a strong redox capacity and improve nitrogen utilization, thereby preventing the long-term flooding of toxic cations and acid substances. Taken together, our results conclude that increased drought stress can reduce the ability of Pinus elliottii seedlings to withstand flooding stress; the seedlings of Pinus elliottii can maintain their growth by accumulating certain nutrient elements under submerged conditions, which implies that this species would be a suitable candidate for reforestation in the TGRA because of its tolerance to submergence.

Erodible coatings based on HPMC and cellulase for oral time-controlled release of drugs.

Oral drug delivery systems for time-controlled release, intended for chronotherapy or colon targeting, are often in the form of coated dosage forms provided with swellable/soluble hydrophilic polymer coatings. These are responsible for programmable lag phases prior to release, due to their progressive hydration in the biological fluids. When based on high-viscosity polymers and/or manufactured by press-coating, the performance of functional hydroxypropyl methylcellulose (HPMC) layers was not fully satisfactory. Particularly, it encompassed an initial phase of slow release because of outward diffusion of the drug through a persistent gel barrier surrounding the core. To promote erosion of such a barrier, the use of a cellulolytic product (Sternzym® C13030) was here explored. For this purpose, the mass loss behavior of tableted matrices based on various HPMC grades, containing increasing percentages of Sternzym® C13030, was preliminarily studied, highlighting a clear and concentration-dependent effect of the enzyme especially with high-viscosity polymers. Subsequently, Sternzym® C13030-containing systems, wherein the cellulolytic product was either incorporated into a high-viscosity HPMC coating or formed a separate underlying layer, were manufactured. Evaluated for release, such systems gave rise to more reproducible profiles, with shortened lag phases and reduced diffusional release, as compared to the reference formulation devoid of enzyme.

Oil release behavior and kinetics of oil-impregnated kapok fiber powder

In this study, kapok fiber powder (KFP) was evaluated as a wicking material for the application of mechanical lubricants. KFP had lengths ranging from several microns to 2 mm, with part of the hollow lumen being compressed. Experiments showed that the oil sorption capacity of KFP for mineral oil and PAO4 was 21.9 g/g, and 19.9 g/g, respectively. The oil release behavior of oil-impregnated KFP was quantitatively evaluated by a device proposed in the present study to simulate the usage of lubricant in bearings. The results indicated a two-step oil release process including a rapid release phase and a slow release phase. The cumulative oil release increased with an increasing oil/fiber ratio and temperature. The release mechanism of oil-impregnated KFP was further investigated by release kinetics models which demonstrated that the oil release followed Fickian diffusion and could be described by the Rigter–Peppas model. These results are proposed to provide a reference for the evaluation of the oil release performance of oil-impregnated wicking materials when they are applied in mechanical bearing field.

Letrozole-loaded nonionic surfactant vesicles prepared via a slurry-based proniosome technology: Formulation development and characterization

Slurry-based Letrozole (LTZ)-loaded proniosomes were designed using sucrose or sorbitol as carriers and various ratios of cholesterol (CH) and Tween 80 (T80) as lipid composition. Proniosomes were hydrated and probe-sonicated to generate nano-vesicles. The proniosome powders were characterized in terms of morphology using scanning electron microscopy, and drug crystallinity using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The niosomes generated from proniosomes were characterized and compared to conventional niosomes, in terms of size, zeta potential, drug entrapment, storage stability, and drug release. All formulations had size measurements in the range of 100–194 nm, polydispersity index (PDI) values below 0.3, and zeta potential values below – 23 mV. Drug entrapment was the highest for niosomes generated from sucrose-based proniosomes (CH:T80; 1:1), reaching 74% compared to less than 50% for conventional niosomes. Storage for 3 months at 4 °C resulted in minor drug leakage whilst most drug was leaked from vesicles stored at room temperature. DSC and XRD studies showed that LTZ was converted into its amorphous form upon incorporation into proniosomes. Drug release exhibited a biphasic pattern, being fast at the first 24 h (up to 65% released) followed by a very slow release phase for a duration of one month, releasing at least 95%. The release profile of niosomes fits best with the Higuchi model. Overall, in this study, a facile approach to generating niosomes incorporating LTZ using a slurry-based proniosome technology was demonstrated. The niosomes provided high drug entrapment and controlled biphasic release over one month.

A novel drug delivery system of mixed micelles based on poly(ethylene glycol)-poly(lactide) and poly(ethylene glycol)-poly(ɛ-caprolactone) for gambogenic acid.

In this study, a novel mixed polymeric micelles formed from biocompatible polymers, poly(ethylene glycol)-poly(lactide) (mPEG-PLA) and poly(ethylene glycol)-poly(ɛ-caprolactone) (mPEG-PCL), used as a novel nanocarrier to encapsulate gambogenic acid (GNA). GNA-loaded mixed polymeric micelles (GNA-MMs) was prepared by cosolvent evaporation method. The mean average size of GNA-MMs was (83.23 ± 1.06) nm (n = 3) and entrapment efficiency (EE%) of GNA-MMs was (90.18 ± 2.59) % (n = 3) as well as (12.36 ± 0.64) % (n = 3) for drug loading (DL%). Transmission electron microscopy revealed that the GNA-MMs were spherical with "core-shell" structures. Compared with free GNA solution, in vitro release of GNA from GNA-MMs showed a two-phase sustained release profile: an initial relatively fast phase and followed by a slower release phase. Pharmacokinetic results also indicated that the GNA-MMs have longer systemic circulation time and slower plasma elimination rate than free GNA solution. Moreover, the in vitro cytotoxicity assay showed that the IC50 values on HepG2 cells for GNA-MMs and free GNA were (5.67 ± 0.02) μM and (9.02 ± 0.03) μM, respectively. In addition, GNA-MMs significantly increased the HepG2 cellular apoptosis in a concentration-dependent manner. In conclusion, the results showed that mPEG-PLA/mPEG-PCL mixed micelles may serve as an ideal drug delivery system for GNA to prolong drug circulation time in body, enhance bioavailability and retained its potent antitumor effect.

Release characteristics of enoxaparin sodium polymethyl methacrylate bone cement

Objective Different concentrations of enoxaparin sodium polymethyl methacrylate (ES-PMMA) bone cement release system were prepared to study the release of a certain amount of ES after adding polymethyl methacrylate (PMMA) bone cement. Methods According to the standard of ISO5833: 2002 Surgical Implants-Acrylic Resin Bone Cement , the enoxaparin sodium cement cylinder test specimen was prepared. The dosage of ES in the experimental groups was 4 000, 8 000, 12 000, 16 000, 20 000 and 24 000 AXaIU for 40 g Palacos®R PMMA bone cement, respectively. The control group was not given enoxaparin sodium. The surface microstructures of bone cements in control and experimental groups were observed by scanning electron microscopy. In the experimental groups, the leach liquor was extracted continuously for 10 days with pH7.4 Tris-HCL buffer, and the anti-Xa factor titer was measured daily. The experimental design and statistical calculation were carried out by the parallel determination method. The leached bone cement was again observed with a scanning electron microscope and compared with that before leaching. Results Scanning electron microscopy showed that enoxaparin sodium was filled into the pores of the PMMA bone cement polymer structure, released from the pores after leaching, and released with a burst effect. The release of the first day in the experimental groups with an amount of ES of 4 000, 8 000, 12 000, 16 000, 20 000 and 24 000 AXaIU was 0.415, 0.858, 1.110, 1.564, 1.952, and 2.513 IU/ml respectively, which was the peak of release. The release amount decreased rapidly on the second day, and entered the low-volume slow release phase on the fourth day. The total release of ES in 10 days was about 1.8% of the total ES loading. Conclusion PMMA bone cement can be used as a carrier for the release of enoxaparin sodium, which can effectively release enoxaparin sodium in a short period of time. Key words: Enoxaparin sodium; Polymethyl methacrylate; Bone cement; Release characteristics

Phomopsidione nanoparticles coated contact lenses reduce microbial keratitis causing pathogens

Microbial keratitis is the infection caused by pathogenic microorganisms that commonly occurs among the contact lens users. Various antimicrobial compounds were coated on contact lenses to kill keratitis causing microorganisms, however these compounds caused several adverse side effects. Hence, the aim of this study is to develop a silicone hydrogel contact lens coated with phomopsidione nanoparticle that inhibit keratitis causing clinical isolates. Phomopsidione nanoparticles were synthesized using polyvinyl alcohol as encapsulant. The nanoparticles showed an average size of 77.45 nm, with neutral surface charge. Two drug release patterns were observed in the drug release profile, which are the initial slow release phase with extended drug release (release rate 46.65 μg/h), and the burst release phase observed on Day 2 (release rate 2224.49 μg/h). This well-regulated drug delivery system enables the control of drug release to meet the therapeutic requirements. On agar diffusion assay, 3 out of 5 test microorganisms were inhibited by phomopsidione nanoparticle coated contact lenses, including two Gram negative bacteria. Besides, all test microorganisms showed at least 99% of growth reduction, with the treatment of the contact lens model. The drug loaded onto the nanoparticles is sufficient to prevent the bacterial growth. In conclusion, this study provides an effective alternative to combat keratitis-causing microorganisms among contact wearers.

Modelling drug release from polymer-free coronary stents with microporous surfaces

Traditional coronary drug-eluting stents (DES) are made from metal and are coated with a permanent polymer film containing an anti-proliferative drug. Subsequent to stent deployment in a diseased coronary artery, the drug releases into the artery wall and helps prevent restenosis by inhibiting the proliferation of smooth muscle cells. Although this technology has proven to be remarkably successful, there are ongoing concerns that the presence of a polymer in the artery can lead to deleterious medical complications, such as late stent thrombosis. Polymer-free DES may help overcome such shortcomings. However, the absence of a rate-controlling polymer layer makes optimisation of the drug release profile a particular challenge. The use of microporous stent surfaces to modulate the drug release rate is an approach that has recently shown particularly promising clinical results. In this study, we develop a mathematical model to describe drug release from such stents. In particular, we develop a mathematical model to describe drug release from microporous surfaces. The model predicts a two-stage release profile, with a relatively rapid initial release of most of the drug, followed by a slower release of the remaining drug. In the model, the slow release phase is accounted for by an adsorption/desorption mechanism close to the stent surface. The theoretical predictions are compared with experimental release data obtained in our laboratory, and good agreement is found. The valuable insights provided by our model will serve as a useful guide for designing the enhanced polymer-free stents of the future.

The influence of pH and enzyme cross-linking on protein delivery properties of WPI-beet pectin complexes

The incorporation of bioactive proteins and peptides into food is associated with the loss of bioactivity due to deactivation in complex food matrices and in digestion systems. In this study, two different types of protein carriers, i.e. biopolymer complexation and complex coacervation were fabricated using whey protein isolation (WPI, 6wt%) and beet pectin (BP, 1.25 and 1.00wt%) at pH5.5 and 3.5, respectively. The release of the encapsulated FITC-BSA, a model bioactive protein, in both carriers in the absence and presence of laccase was investigated at both pH7.0 and 4.0. Release of FITC-BSA from both lyophilized WPI-beet pectin biopolymer complexation and complex coacervation were biphasic with an initial burst release followed by a slower release phase. The addition of laccase in biopolymer complexation increased the loading efficiency from 44.95% to 52.15% and slowed down the burst release of FITC-BSA but did change the biphasic release pattern. Laccase-cross linked WPI (6wt%)-BP (1wt%) complex coacervation had highest FITC-BSA loading efficiency (96.90%). The release of the embedded FITC-BSA in this carrier at both pH4 and 7 was in a gradual manner and the profile can be fit to zero order kinetics over the 72h study period suggesting enzymatically reinforced complex coacervation between the protein and the negatively charged beet pectin can restrain the burst release of FITC-BSA. These results indicate that laccase cross-linked WPI-beet pectin complex coacervation can be a good carrier system for delivering hydrophilic bioactive proteins or peptides successfully with enhanced loading parameters and sustained release profiles.

Release Kinetics of Si, Al, Fe, and Mn from Acid Soils in the Presence of EGCG

ABSTRACTPlant polyphenols can affect soil processes. In the present study, batch experiments were conducted to study the effects of epigallocatechin gallate on the release kinetics of silicon (Si), aluminum (Al), iron (Fe), and manganese (Mn) from acid Anthrosol and Luvisol. The results indicated that the optimal model describing the release kinetics of these elements was a double constant, simple Elovich, or parabolic diffusion equation, and a first-order equation was not suitable. These elements went through an initial rapid-release phase, followed by a slower-release phase. The order of release amounts and rates for Anthrosol was Si > Al > Fe > Mn, but they were different at different phases. However, the order for Luvisol was always Al > Mn > Si > Fe. Meanwhile, the release amount and rate of every element was in the order Luvisol > Anthrosol. The results of this study could help to resolve Al and Mn toxicity in acid soils.

Cancer Targeting Potential of 99mTc-Finasteride in Experimental Model of Prostate Carcinogenesis.

This study aimed to radiolabel finasteride, a novel 5α-reductase inhibitor, to evaluate its cancer targeting potential in experimental model of prostate carcinogenesis. Finasteride was effectively radiolabeled with 99mTc and showed >90% labeling efficiency. The radiopharmaceutical was found to be stable up to 6 hours in rat serum at 37°C. The blood kinetics of the 99mTc-finasteride followed a biphasic release pattern, whereby fast-release phase was observed at 15 seconds and a slow-release phase was observed after 30 minutes of administration. The plasma protein binding of the radio complex observed was 83.89%. For biodistribution studies, the rats were divided into two groups. Group I served as normal controls, while group II was subjected to carcinogen N-methyl-N-nitrosourea (MNU) and hormone testosterone propionate (T) for induction of prostate carcinogenesis, which was confirmed histopathologically. The biodistribution studies on control and carcinogen-treated rats revealed a significant percent-specific uptake in prostate, which was found to be increased significantly as a function of time. The most significant finding of the study was an increase in the percent-specific uptake in prostate of carcinogen-treated animals when compared to the percent-specific uptake in prostate of normal rats after 2 and 4 hours postinjection. The study concludes that 99mTc-finasteride possesses selectively toward prostate cancer tissue and can be explored further for its role in detection of prostate cancer.

Release behavior and kinetic evaluation of formaldehyde from cotton clothing fabrics finished with DMDHEU-based durable press agents in water and synthetic sweat solution

The durable press-finished cotton fabrics were prepared with dimethylol dihydroxy ethylene urea (DMDHEU) and methylated DMDHEU, and tested for formaldehyde release in distilled water or synthetic sweat at pH 5 or 8 to simulate the extraction of formaldehyde by sweat under similar wearing conditions. The release mechanism of formaldehyde was studied and compared using three diffusion kinetic models. The effect of release conditions and finishing process on the formaldehyde release was also investigated. The results indicated that the release process of formaldehyde from the finished fabric includes a burst release phase and a slow release phase, which is explained by five different sources. The formaldehyde release mechanism followed the Fickian mode, and could be described by Higuchi, Double phases and Korsmeyer–Peppas kinetic equations, respectively. Higher formaldehyde release was found at pH 8 than that at pH 5. Formaldehyde showed a lower release rate in synthetic sweat solution than that in water under the same conditions. Increasing water volume or temperature enhanced the formaldehyde release, suggesting that a high sweat rate and skin temperature may accelerate the formaldehyde release. When finishing the fabrics, a higher concentration of finishing agent and the addition of softener accelerated the formaldehyde release. However, increasing catalyst concentration and curing temperature could reduce the formaldehyde release. It is concluded that formaldehyde release can be effectively reduced by optimizing the durable press finishing process of cotton fabrics, thus possibly decreasing risk of allergic contact dermatitis from formaldehyde in textiles.

Chitosan-Alginate Nanoparticle System Efficiently Delivers Doxorubicin to MCF-7 Cells

A chitosan-alginate nanoparticle system encapsulating doxorubicin (DOX) was prepared by a novel ionic gelation method using alginate as the crosslinker. These nanoparticles were around 100 nm in size and more stable with higher positive zeta potential and had higher % encapsulation efficiency (95%) than DOX loaded chitosan nanoparticles (DOX Csn NP) crosslinked with sodium tripolyphosphate (STPP). FTIR spectroscopy and thermogravimetric analysis revealed successful loading of DOX.In vitrodrug release showed an initial release phase followed by slow release phase with higher cumulative release obtained with DOX loaded chitosan-alginate nanoparticles (DOX Csn-Alg NP). Thein vitrocytotoxicity of DOX released from the two nanoparticle systems showed a notable difference on comparison with that of free DOX on the MCF-7 cell line. The SRB assay, AO/EB staining, and fluorescence uptake study indicated that free DOX only showed dose dependent cytotoxicity, whereas both dose and time dependency were exhibited by the two sets of NPs. While both systems show sustained release of DOX, from the cell viability plots, DOX Csn-Alg NPs showed their superiority over DOX Csn NPs. The results obtained are useful for developing DOX Csn-Alg NPs as a sustained release carrier system for DOX.

Synaptotagmin-1 and -7 Are Redundantly Essential for Maintaining the Capacity of the Readily-Releasable Pool of Synaptic Vesicles.

In forebrain neurons, Ca2+ triggers exocytosis of readily releasable vesicles by binding to synaptotagmin-1 and -7, thereby inducing fast and slow vesicle exocytosis, respectively. Loss-of-function of synaptotagmin-1 or -7 selectively impairs the fast and slow phase of release, respectively, but does not change the size of the readily-releasable pool (RRP) of vesicles as measured by stimulation of release with hypertonic sucrose, or alter the rate of vesicle priming into the RRP. Here we show, however, that simultaneous loss-of-function of both synaptotagmin-1 and -7 dramatically decreased the capacity of the RRP, again without altering the rate of vesicle priming into the RRP. Either synaptotagmin-1 or -7 was sufficient to rescue the RRP size in neurons lacking both synaptotagmin-1 and -7. Although maintenance of RRP size was Ca2+-independent, mutations in Ca2+-binding sequences of synaptotagmin-1 or synaptotagmin-7—which are contained in flexible top-loop sequences of their C2 domains—blocked the ability of these synaptotagmins to maintain the RRP size. Both synaptotagmins bound to SNARE complexes; SNARE complex binding was reduced by the top-loop mutations that impaired RRP maintenance. Thus, synaptotagmin-1 and -7 perform redundant functions in maintaining the capacity of the RRP in addition to nonredundant functions in the Ca2+ triggering of different phases of release.