Physicomechanical properties of sintered scaffolds formed from porous and protein-loaded poly(DL-lactic-co-glycolic acid) microspheres for potential use in bone tissue engineering

An injectable poly(DL-lactic-co-glycolic acid) (PLGA) system comprising both porous and protein-loaded microspheres capable of forming porous scaffolds at body temperature was developed for tissue regeneration purposes. Porous and non-porous (lysozyme loaded) PLGA microspheres were formulated to represent ‘low molecular weight’ 22–34 kDa, ‘intermediate molecular weight’ (IMW) 53 kDa and ‘high molecular weight’ 84–109 kDa PLGA microspheres. The respective average size of the microspheres was directly related to the polymer molecular weight. An initial burst release of lysozyme was observed from both microspheres and scaffolds on day 1. In the case of the lysozyme-loaded microspheres, this burst release was inversely related to the polymer molecular weight. Similarly, scaffolds loaded with 1 mg lysozyme/g of scaffold exhibited an inverse release relationship with polymer molecular weight. The burst release was highest amongst IMW scaffolds loaded with 2 and 3 mg/g. Sustained lysozyme release was observed after day 1 over 50 days (microspheres) and 30 days (scaffolds). The compressive strengths of the scaffolds were found to be inversely proportional to PLGA molecular weight at each lysozyme loading. Surface analysis indicated that some of the loaded lysozyme was distributed on the surfaces of the microspheres and thus responsible for the burst release observed. Overall the data demonstrates the potential of the scaffolds for use in tissue regeneration.     

Poly(ethylene glycol)-co-methacrylamide-co-acrylic acid based nanogels for delivery of doxorubicin

Polymeric nanogels have been widely explored for their potential application as delivery carriers for cancer therapeutics. The ability of nanogels to encapsulate therapeutics by simple diffusion mechanism and the ease of their fabrication to impart target specificity in addition to their ability to get internalized into target cells make them good candidates for drug delivery. The present study aims to investigate the applicability of poly(ethylene glycol)-co-methacrylamide-co-acrylic acid (PMA)-based nanogels as a viable option for the delivery of doxorubicin (DOX). The nanogels were synthesized by free radical polymerization in an inverse mini-emulsion and characterized by nuclear magnetic resonance spectroscopy (¹H NMR), Fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy (TEM), X-ray diffraction and differential scanning calorimetry. DOX was physically incorporated into the nanogels (PMA-DOX) and the mechanism of its in vitro release was studied. TEM experiment revealed spherical morphology of nanogels and the hydrodynamic diameter of the neat nanogels was in the range of 160 ± 46.95 nm. The size of the nanogels increased from 235.1 ± 28.46 to 403.7 ± 89.89 nm with the increase in drug loading capacity from 4.68 ± 0.03 to 13.71 ± 0.01%. The sustained release of DOX was observed upto 80 h and the release rate decreased with increased loading capacity following anomalous release mechanism as indicated by the value of diffusion exponent (n = 0.64–0.75) obtained from Korsmeyer–Peppas equation. Further, cytotoxicity evaluation of PMA-DOX nanogels on HeLa cells resulted in relatively higher efficacy (IC₅₀~5.88 μg/mL) as compared to free DOX (IC₅₀~7.24 μg/mL) thus demonstrating that the preparation is potentially a promising drug delivery carrier.     

PLGA microspheres by Supercritical Emulsion Extraction: a study on insulin release in myoblast culture

Supercritical Emulsion Extraction in a Continuous operation layout is proposed for the production of poly-lactic-co-glycolic acid (PLGA) microspheres loaded with insulin, selected as a model of bioactive signal. Microspheres with different mean sizes of 2?μm (±0.9?μm) and 3?μm (±2.2?μm) and insulin loadings of 3 and 6?mg/g were obtained by processing different water–oil–water emulsions; an encapsulation efficiency of about 60% w/w was measured in all cases. Insulin release profiles from PLGA microspheres were also characterized in two different media (Phosphate-Buffered Saline and Dulbecco’s Modified Eagle Medium) and kinetic constants were estimated by using a model proposed in literature. The produced microspheres were, then, used for the cultivation of rat embryonic ventricular myoblasts in a serum-free medium to monitor the biological effect of the released insulin. The best cell viability and proliferation, supported by released insulin, was monitored when microspheres with mean size of 3?μm loaded with 3?mg/g of insulin were added.     

A dual-application poly (dl-lactic-co-glycolic) acid (PLGA)-chitosan composite scaffold for potential use in bone tissue engineering

The development of patient-friendly alternatives to bone-graft procedures is the driving force for new frontiers in bone tissue engineering. Poly (dl-lactic-co-glycolic acid) (PLGA) and chitosan are well-studied and easy-to-process polymers from which scaffolds can be fabricated. In this study, a novel dual-application scaffold system was formulated from porous PLGA and protein-loaded PLGA/chitosan microspheres. Physicochemical and in vitro protein release attributes were established. The therapeutic relevance, cytocompatibility with primary human mesenchymal stem cells (hMSCs) and osteogenic properties were tested. There was a significant reduction in burst release from the composite PLGA/chitosan microspheres compared with PLGA alone. Scaffolds sintered from porous microspheres at 37 °C were significantly stronger than the PLGA control, with compressive strengths of 0.846 ± 0.272 MPa and 0.406 ± 0.265 MPa, respectively (p < 0.05). The formulation also sintered at 37 °C following injection through a needle, demonstrating its injectable potential. The scaffolds demonstrated cytocompatibility, with increased cell numbers observed over an 8-day study period. Von Kossa and immunostaining of the hMSC-scaffolds confirmed their osteogenic potential with the ability to sinter at 37 °C in situ.     

PEGylated TNF-related apoptosis-inducing ligand (TRAIL) for effective tumor combination therapy

Although PEGylated TNF-related apoptosis-inducing ligand (PEG-TRAIL) has good tumor cell specificity and stability, its therapeutic potential is restricted by the development of tumor cell resistance. The purpose of this study was to develop an effective combination therapy with sustained biological activity based on microspheres. Doxorubicin (DOX), PEG-TRAIL, and DOX plus PEG-TRAIL (dual agent) were microencapsulated into poly (lactic-co-glycolic acid) (PLGA) microspheres using a double-emulsion solvent extraction method. Prepared dual agent microspheres showed the encapsulation efficiency 69.4 ± 2.3 for DOX and 87.7 ± 2.9% for PEG-TRAIL. Potential anti-tumor efficacy of this system was investigated in vitro and in vivo in a human colon cancer (HCT116) and in a human prostate cancer (PC-3). DOX and PEG-TRAIL release from dual agent microspheres were biologically active and significantly inhibited the TRAIL-sensitive HCT116 and resistant PC-3 cells in vitro. Dual agent microspheres simultaneous delivery of DOX and PEG-TRAIL was superior to all other DOX or PEG-TRAIL microspheres in vivo. A single local injection of PLGA microspheres loaded with low amounts of DOX, PEG-TRAIL, or dual agent resulted in 14.8, 30.2, and 63.6% reductions in HCT116 tumor volume and 20.4, 14.2, and 67.7% reductions in PC-3 tumor volume at 35 days. Our findings show that dual agent microspheres offer a promising means of delivering DOX and PEG-TRAIL to tumor sites.     

Inhibitory effect of doxycycline against dengue virus replication in vitro

Doxycycline is an antibiotic derived from tetracycline that possesses antimicrobial and anti-inflammatory activities. Antiviral activity of doxycycline against dengue virus has been reported previously; however, its anti-dengue properties need further investigation. This study was conducted to determine the potential activity of doxycycline against dengue virus replication in vitro. Doxycycline inhibited the dengue virus serine protease (DENV2 NS2B-NS3pro) with an IC₅₀ value of 52.3 ± 6.2 μM at 37 °C (normal human temperature) and 26.7 ± 5.3 μM at 40 °C (high fever temperature). The antiviral activity of doxycycline was first tested at different concentrations against DENV2 using a plaque-formation assay. The virus titter decreased significantly after applying doxycycline at levels lower than its 50 % cytotoxic concentration (CC₅₀, 100 μM), showing concentration-dependent inhibition with a 50 % effective concentration (EC₅₀) of approximately 50 μM. Doxycycline significantly inhibited viral entry and post-infection replication of the four dengue serotypes, with serotype-specific inhibition (high activity against DENV2 and DENV4 compared to DENV1 and DENV3). Collectively, these findings underline the need for further experimental and clinical studies on doxycycline, utilizing its anti-dengue and anti-inflammatory activities to attenuate the clinical symptoms of dengue virus infection.     

PLGA microsphere/calcium phosphate cement composites for tissue engineering: in vitro release and degradation characteristics

Bone cements with biodegradable poly(lactic-co-glycolic acid) (PLGA) microspheres have already been proven to provide a macroporous calcium phosphate cement (CPC) during in situ microsphere degradation. Furthermore, in vitro/in vivo release studies with these PLGA microsphere/CPC composites (PLGA/CPCs) showed a sustained release of osteo-inductive growth factor when drug was distributed inside/onto the microspheres. The goal of this study was to elucidate the mechanism behind drug release from PLGA/CPC. For this, in vitro release and degradation characteristics of a low-molecular-weight PLGA/CPC (M(w) = 5 kg/mol) were determined using bovine serum albumin (BSA) as a model protein. Two loading mechanisms were applied; BSA was either adsorbed onto the microspheres or incorporated inside the microspheres during double-emulsion. BSA release from PLGA microspheres and CPC was also measured and used as reference. Results show fast degrading polymer microspheres which produced a macroporous scaffold within 4 weeks, but also showed a concomitant release of acidic degradation products. BSA release from the PLGA/CPC was similar to the CPC samples and showed a pattern consisting of a small initial release, followed by a period of almost no sustained release. Separate PLGA microspheres exhibited a high burst release and release efficiency that was higher with the adsorbed samples. Combining degradation and release data we can conclude that for the PLGA/CPC samples BSA re-adsorbed to the cement surface after being released from the microspheres, which was mediated by the pH decrease during microsphere degradation.     

RhBMP-2-loaded Poly(lactic-co-glycolic acid) microspheres fabricated by coaxial electrospraying for protein delivery

In this study, we fabricated recombinant human bone morphogenetic protein-2 (rhBMP-2) loaded Poly(lactic-co-glycolic acid) (PLGA) microspheres with core–shell structures and particle sizes ranging from 2.5 to 8 μm by coaxial electrospraying. The manufacturing process of core–shell microspheres by coaxial electrospraying is simpler than that with other methods, and a smaller diameter can be obtained. The microspheres were analyzed by environmental scanning electron microscopy, transmission electron microscopy (TEM), and laser scanning confocal microscopy (LSCM). Moreover, the drug release profiles and degradation of rhBMP-2-loaded PLGA microspheres in vitro were investigated for 21 days and for 7 weeks, respectively. The rhBMP-2 was stabilized by using bovine serum albumin (BSA) to ensure protein activity in the electrospraying process. Fluorescently labeled protein that was loaded into the core–shell PLGA microspheres was verified by LSCM. The distinct layered structure that existed in the manufactured core–shell microspheres can be observed by TEM. Cell Counting Kit-8 (CCK-8) indicated that the core–shell PLGA microspheres loaded with rhBMP-2 have great potential for the treatment of bone defects, for bone regeneration, and in bone tissue engineering.     

Development and validation of an immunochromatographic test strip for rapid detection of doxycycline residues in swine muscle and liver

A one-step lateral flow immunochromatographic technique using colloidal gold-labelled monoclonal antibody (Mab) was developed for the rapid detection of doxycycline (DOX) residues in swine tissues. For this purpose, a Mab against DOX named as 2.3/3A6 with low cross-reactivity (CR) to other tetracyclines (TCs) was produced. The sensitivity of the test strip was as low as 7 ng/mL for DOX and the half maximal inhibitory concentration (IC₅₀) was calculated to be 22±2 ng/mL by relative optical density. The test can be completed within 10 min and the detection limit was 20 ng/mL in unaided visual assessment. Recoveries in samples spiked with DOX at concentrations of 20, 40 and 80 ng/g, were demonstrated to be from 81% to 95% for muscle samples and from 81% to 92% for liver samples. The intra-assay and inter-assay coefficients of variation (CVs) ranged from 3% to 6% and from 4% to 8%, respectively. Comparing with high performance liquid chromatography (HPLC) method in sensitivity and accuracy for the detection of DOX in swine tissues, the test strip showed good agreement. Therefore, the test strip is suitable for rapid and reliable determination of DOX residues in swine tissues semi-quantitatively or qualitatively.     

Porous silicon oxide–PLGA composite microspheres for sustained ocular delivery of daunorubicin

A water-soluble anthracycline antibiotic drug (daunorubicin, DNR) was loaded into oxidized porous silicon (pSiO₂) microparticles and then encapsulated with a layer of polymer (poly lactide-co-glycolide, PLGA) to investigate their synergistic effects in control of DNR release. Similarly fabricated PLGA–DNR microspheres without pSiO₂, and pSiO₂ microparticles without PLGA were used as control particles. The composite microparticles synthesized by a solid-in-oil-in-water emulsion method have mean diameters of 52.33 ± 16.37 μm for PLGA–pSiO₂_21/40–DNR and the mean diameter of 49.31 ± 8.87 μm for PLGA–pSiO₂_6/20–DNR. The mean size, 26.00 ± 8 μm, of PLGA–DNR was significantly smaller, compared with the other two (P < 0.0001). Optical microscopy revealed that PLGA–pSiO₂–DNR microspheres contained multiple pSiO₂ particles. In vitro release experiments determined that control PLGA–DNR microspheres completely released DNR within 38 days and control pSiO₂–DNR microparticles (with no PLGA coating) released DNR within 14 days, while the PLGA–pSiO₂–DNR microspheres released DNR for 74 days. Temporal release profiles of DNR from PLGA–pSiO₂ composite particles indicated that both PLGA and pSiO₂ contribute to the sustained release of the payload. The PLGA–pSiO₂ composite displayed a more constant rate of DNR release than the pSiO₂ control formulation, and displayed a significantly slower release of DNR than either the PLGA or pSiO₂ formulations. We conclude that this system may be useful in managing unwanted ocular proliferation when formulated with antiproliferation compounds such as DNR.     

Inflammatory mediators of systemic inflammation in neonatal sepsis

Objective and design

Sepsis refers to severe systemic inflammation in response to invading pathogens. To understand the molecular events that initiate the systemic inflammatory response, various inflammatory mediators were analyzed in neonatal sepsis samples and compared with normal samples.

Materials and methods

We initially measured the levels of the various classical inflammatory mediators such as acute phase proteins [C-reactive protein (CRP) and procalcitonin (PCT)], granule-associated mediators (NE, MPO and NO), proinflammatory cytokines [tumour necrosis factor-α (TNFα), IL-1β and IL-6), antiinflammatory cytokines (IL-10 and IL-13) and chemokines [IL-8 and monocyte chemotactic protein (MCP-1)] and novel cytokines (IL-12/IL-23p40, IL-21 and IL-23) using ELISA. We also used the human inflammation antibody array membrane to profile the inflammatory proteins that are involved in neonatal sepsis.

Results

There were significantly higher levels of CRP (5.4 ± 0.70 mg/L), PCT (1.500 ± 0.2400 μg/L); NE (499.2 ± 22.01 μg/L), NO (54.22 ± 3.131 μM/L); TNFα (396.6 ± 37.40 pg/mL), IL-1β (445.3 ± 34.25 pg/mL), IL-6 (320.9 ± 43.38 pg/mL); IL-8 (429.5 ± 64.08 pg/mL) MCP-1 (626.25 ± 88.91 pg/mL), IL-10 (81.80 ± 9.45 pg/mL), IL-12/IL-23p40 (30.25 ± 0.6 pg/mL), IL-21 (8,263.3 ± 526.8 pg/mL) and IL-23 (6,083 ± 781.3 pg/mL) in neonates with sepsis compared to normal. The levels of MPO (21.20 ± 3.099 ng/mL) were downregulated, whereas there was no change in IL-13 (188.7 ± 10.63 pg/mL) levels in septic neonates when compared with normal. Using the human inflammation antibody array membrane, we detected the presence of 17 inflammatory proteins such as IL-3, IL6R, IL12p40, IL-16, TNFα, TNFβ, TNF R1, chemokines I-309, IP-10 (IFN-γ inducible protein 10), MCP-1, MCP-2, MIP 1β (macrophage inflammatory protein), MIP-1δ, eotaxin-2, growth factors TGFβ1 (transforming growth factor beta), PDGF (platelet derived growth factor), and cell adhesion molecule ICAM-1 (intracellular adhesion molecule) that were upregulated whereas RANTES which was downregulated in neonatal sepsis.

Conclusion

The simultaneous secretion and release of multiple mediators such as proinflammatory cytokines and chemokines, cell adhesion molecules, and growth factors were found to be involved in the initiation of systemic inflammation in neonatal sepsis. Therefore, measuring the concentration of multiple mediators may help in the early detection of neonatal sepsis and help to avoid unnecessary antibiotic treatment.     

Improved antifilarial activity of ivermectin in chitosan–alginate nanoparticles against human lymphatic filarial parasite, Brugia malayi

The current antifilarial treatments are not up to the mark partly due to deep location of filarial parasites in the human lymphatic system. We report here on the improvement in the antifilarial activity of ivermectin (IVM) using chitosan–alginate nanoparticles prepared by modified complex coacervation method. The nanoparticles were spherical having 155 nm size and 4.56 and 75.67 % loading and entrapment efficiency respectively for IVM. The delivery system maintained the sustained release and significantly augmented the microfilaricidal (MIF) activity at a single low dose (200 μg/kg body weight, subcutaneously) in contrast to much higher dose of free ivermectin (400 μg/kg body weight, subcutaneously) against human lymphatic filariid, Brugia malayi in rodent host, Mastomys coucha. To substantiate increase in MIF activity, pharmacokinetics study was designed on Wistar rats which revealed a greater peak plasma concentration (45.3?±?1.79 ng/ml), area under the concentration curve (298?±?38.7 ng d/ml) and extended mean residence time (23.4?±?8.56 days)of IVM in chitosan–alginate nanoparticles. Administration of 25 mg/kg of diethylcarbamazine following nanoparticle therapy significantly improved the MIF and macrofilaricidal action of encapsulated drug and was considered superior in this study.     

Curcumin loaded NIPAAM/VP/PEG-A nanoparticles: physicochemical and chemopreventive properties

This study aims at modifying the synthesis method of preparing N-isopropylacrylamide (NIPAAM)/N-vinyl-2-pyrrolidone (VP)/Polyethylene glycol monoacrylate (PEG-A) polymeric nanoparticles encapsulating curcumin as a model drug. The optimal concentration of nanoparticle reagents was determined using Fourier Transform Infrared Spectroscopy. Curcumin nanoparticles mean hydrodynamic size was found to be 104?nm with zeta potential of 3?±?13?mV. The release kinetic study of curcumin nanoparticles indicates that a maximum release of curcumin at 24?h positively correlates with increase in temperature; however, change in pH did not produce any substantial drug release. In vitro cell viability assay performed on cancer cells exposed to various concentrations of model compound displayed the IC50 ranging between 100 and 200?μg/mL for human prostate cancer cells (PC3 cells) and 50 and 200?μg/mL for epidermoid carcinoma (A431 cell line). The Hoechst staining and phase contrast micrographs for 48?h exposure of curcumin nanoparticles at a concentration of 400?μg/mL resulted in almost 92% of cells death in both cell lines. This study concludes that the physiochemical characteristics of NIPAAM/VP/PEG-A polymer with key features of water solubility, sustained drug release, small particle size make these nanoparticles a prominent drug delivery device.     

Biodegradable and complexed microspheres used for sustained delivery and activity protection of SOD

To develop a new protein delivery system for superoxide dismutase (SOD), biodegradable materials like poly(DL-lactide-co-glycolide) (PLGA), alginate, and chitosan were used for preparing PLGA microspheres and alginate-chitosan microspheres, which were used for encapsulating protein. Alginate-chitosan microspheres showed much higher entrapment efficiency (91.08% +/- 1.28%) than that of PLGA microspheres (36.42% +/- 1.81%). In vitro release study showed that SOD presented a sustained release character in the preparation of these biodegradable materials. After 15 days, 43.72% +/- 0.43% of protein was released from alginate-chitosan microspheres, while there was 62.96% +/- 3.95% of protein release from PLGA microspheres. However, alginate-chitosan demonstrated that it was a better material to control the burst release of protein from microspheres. Furthermore, SOD activity in microspheres was evaluated, and the results showed that microspheres protected the activity of protein to some extent. Finally, PLGA-alginate-chitosan complex microspheres were constructed and the release character in vitro demonstrated that this preparation could not only prolong the release of drug but also decrease the burst release.     

Poly(l-glutamic acid)/chitosan polyelectrolyte complex porous microspheres as cell microcarriers for cartilage regeneration

In this study a novel kind of porous poly(l-glutamic acid) (PLGA)/chitosan polyelectrolyte complex (PEC) microsphere was developed through electrostatic interaction between PLGA and chitosan. By adjusting the formula parameters chitosan microspheres with an average pore size of 47.5 ± 5.4 μm were first developed at a concentration of 2 wt.% and freeze temperature of −20 °C. For self-assembly of the PEC microspheres porous chitosan microspheres were then incubated in PLGA solution at 37 °C. Due to electrostatic interaction a large amount of PLGA (110.3 μg mg⁻¹) was homogeneously absorbed within the chitosan microspheres. The developed PEC microspheres retained their original size, pore diameters and interconnected porous structure. Fourier transform infrared spectroscopy, thermal gravimetric analysis and zeta potential analysis revealed that the PEC microspheres were successfully prepared through electrostatic interaction. Compared with microspheres fabricated from chitosan, the porous PEC microspheres were shown to efficiently promote chondrocyte attachment and proliferation. After injection subcutaneously for 8 weeks PEC microspheres loaded with chondrocytes were found to produce significant more cartilaginous matrix than chitosan microspheres. These results indicate that these novel fabricated porous PLGA/chitosan PEC microspheres could be used as injectable cell carriers for cartilage tissue engineering.     

Chemical composition,antioxidant activity and antifungal effects of five Iranian essential oils against Candida strains isolated from urine samples

Systemic candidiasis has become an emerging fungal infection in recent years. Anti-Candida resistance to conventional antifungal agents has subsequently increased. This study reported the chemical composition, antioxidant and anti-Candida activity of Origanum majorana, Artemisia dracunculus, Cymbopogon citrate, Cinnamomum verum and Caryophyllus aromaticus essential oils. Different Candida species, from urine tracts of hospitalized patients, were included to be challenged with understudied essential oils. Chemical compositions were determined using gas chromatography/mass spectroscopy (GC/MS) analysis and antioxidant activity was measured using DDPH assay. MIC of these essential oils was evaluated using broth micro-dilution test. Caryophyllus aromaticus had the highest antioxidant activity while the lowest antioxidant activity was for Artemisia dracunculus. MICs of Cinnamomum verum, Caryophillium aromaticus, Artemisia dracunculus, Origanum vulgare and Cymbopogon citratus essential oils ranged from 125 to 175 μg/mL (mean value: 147.7 ± 25.5 μg/mL), 700 to 1000 μg/mL (mean value: 740.9 ± 105.4 μg/mL), 1000 to 2000 μg/mL (mean value: 1454.5 ± 509.6 μg/mL), 173 to 350 μg/mL (mean value: 208 ± 55.8 μg/mL) and 125 to 175 μg/mL (mean value: 156.8 ± 24.6 μg/mL) for different Candida species, respectively. In general, natural compounds are suitable to be used as anti-Candida and antioxidant agents. However in this stage, these compounds could be applied as supplementary agents along with conventional antifungal drugs.     

Synthetic polymannose as a drug carrier: synthesis,toxicity and anti-fungal activity of polymannose-amphotericin B conjugates

Polymannose (PM) having a weight-average molar mass (M_w) of 30–53 kDa was synthesized by the polycondensation of mannose using phosphorous acid as the catalyst and characterized by various techniques such as NMR, IR, GPC and polarimetry. 2D NMR results confirmed the presence of (1 → 6)-linked α-D-mannose residues as backbone with O-3 and O-2 substituted linear or branched chains in PM. Amphotericin B (AmB) was conjugated to periodate-oxidized PM through Schiff’s linkages at 20 wt% concentration. The AmB-PM conjugates were highly soluble in phosphate buffered saline (180–250 mg/mL), exhibited negligible hemolytic potential to human erythrocytes even at a concentration of 200 μg/mL (equivalent to ~40 μg/mL AmB) and were non-toxic to human embryonic kidney (HEK293T) cells even at a concentration of 250 μg/mL (equivalent to ~50 μg/mL AmB). The minimum inhibitory concentration of the AmB-PM conjugates against C. albicans, C. parapsilosis and C. neoformans was in the range of 0.5–1.0 μg/mL. Mannose receptors are widely expressed on myeloid cells such as macrophages, neutrophils, and dendritic cells. Therefore, apart from treating fungal infections, AmB-PM conjugates also may have therapeutic potential for the treatment of macrophage-associated diseases such as leishmaniasis where mannose receptors are overexpressed.     

Preparation of biodegradable microspheres of testosterone with poly(D,L-lactide-co-glycolide) and test of drug release in vitro

Biodegradable microspheres formulation of testosterone (T) can be used as a new physiological approach for androgen replacement in hypogonadal men. In this study, poly(D,L-lactide-co-glycolide) (PLGA) microspheres containing T were prepared by a solvent-evaporation/solvent-diffusion process and the drug release tests of the microspheres were carried out in vitro. T/PLGA microspheres with good yield, desired size and satisfied drug loading were obtained. A significant testosterone sustained release was shown in the drug release tests in vitro. Since PLGA microspheres preparations are normally sterilized by colbat-60 irradiation, the effects of 25 kGy colbat-60 irradiation on physicochemical properties and in vitro drug release profile of T/PLGA microsphere were investigated. The results showed that the irradiation didn't have any effects on the physicochemical properties of T. Though about one-third decrease in molecular weight of PLGA was caused by the irradiation, no significant changes were observed on the drug release profile in vitro.     

Larvicidal activity of lipophilic extract of Hypericum carinatum (Clusiaceae) against Aedes aegypti (Diptera: Culicidae) and benzophenones determination

In this study, the larvicidal activity of an enriched fraction of the major lipophilic phenolic compounds from Hypericum carinatum Griseb. (Clusiaceae) was investigated against larvae of Aedes aegypti (Diptera: Culicidae), the main vector of dengue virus in Brazil. The larval mortality rate ranged 37.33 to 72.00 % at concentrations of 66–200 μg/mL. The effect demonstrated to be dose-dependent. The lethal concentration 50 % and confidence interval were 100 and 88–111 μg/mL, respectively. The results could be attributed to the presence of cariphenone A and cariphenone B in concentrations of 1.24?±?0.04 and 0.56?±?0.01 %, respectively, determined by high-performance liquid chromatography. Besides, the results reinforce the potential of genus Hypericum as source of alternative insecticides.     

Sustained release of PTH(1-34) from PLGA microspheres suppresses osteoarthritis progression in rats

We previously reported that PTH(1-34) inhibits the terminal differentiation of articular chondrocytes and, in turn, suppresses the progression of osteoarthritis (OA). However, this treatment requires an injection of PTH(1-34) once every 3 days over the treatment period. In this study, we studied the effect of sustained administration of PTH(1-34) in a papain-induced OA rat model. We developed an effective controlled-release system for prolonging the treatment duration of an intra-articular injection for OA treatment in rats. The effects of released PTH(1-34) from PLGA(65:35)-encapsulated PTH(1-34) microspheres (PTH/PLGA) on papain-induced OA in rat knees were studied. Microsphere morphology was observed in vitro by scanning electron microscopy, and microsphere size was determined with a particle size analyzer. The PTH(1-34) encapsulation efficiency and release profile, as well as the toxicity of PTH/PLGA, were examined. The bioactivity of released PTH(1-34) was tested by examining cAMP levels in MC3T3E1 cells. In vivo, we evaluated the changes of localized GAG, Col II, and Col X in the articular cartilage of rat knees. Our results demonstrated that the surface of the PLGA microspheres was smooth, and the size of the microspheres was in the range of 51-127 μm. PTH/PLGA microspheres sustainably released PTH(1-34) for 19 days with a concentration range of 0.01-100 nM that covered the expected concentration of 10nM at 37°C. The cAMP levels of MC3T3E1 cells were elevated in the response to released PTH(1-34) from PTH/PLGA microspheres, indicating that the released PTH(1-34) is bioactive. Most importantly, intra-articular treatment with either PTH(1-34) (0.1-100 nM) 3 days/injection or PTH/PLGA microspheres (15 days/injection) for 5 weeks revealed the similar effect on suppressing papain-induced OA changes (decreasing GAG and Col II and increasing Col X) in rat knee cartilage. The effect of PTH/PLGA microspheres on suppressing OA progression was similar to that of a once-every-three-day injection of PTH(1-34), indicating that both the sustained and intermittent action of PTH(1-34) effectively suppress OA progression. The developed PLGA microspheres with sustained release and long-term effect may be potent carriers for PTH(1-34) used to treat early OA.