The biocontrol agent Lactiplantibacillus plantarum AMBP214 is dispersible to plants via bumblebees

IMPORTANCE

Plant protection products are essential for ensuring food production, but their use poses a threat to human and environmental health, and their efficacy is decreasing due to the acquisition of resistance by pathogens. Stricter regulations and consumer demand for cleaner produce are driving the search for safer and more sustainable alternatives. Microbial biocontrol agents, such as microorganisms with antifungal activity, have emerged as a promising alternative management strategy, but their commercial use has been limited by poor establishment and spread on crops. This study presents a novel system to overcome these challenges. The biocontrol agent Lactiplantibacillus plantarum AMBP214 was spray-dried and successfully dispersed to strawberry flowers via bumblebees. This is the first report of combining spray-dried, non-spore-forming bacteria with pollinator-dispersal, which scored better than the state-of-the-art in terms of dispersal to the plant (CFU/flower), and resuscitation of the biocontrol agent. Therefore, this new entomovectoring system holds great promise for the use of biocontrol agents for disease management in agriculture.

The influence on the oral bioavailability of solubilized and suspended drug in a lipid nanoparticle formulation: in vitro and in vivo evaluation

The present study investigated the oral bioavailability of celecoxib when incorporated into solid lipid nanoparticles either dissolved or suspended. In vitro drug release in different media, in vivo performance, and in vitro-in vivo correlation were conducted. The results revealed that the compound was successfully encapsulated into the nanocarriers with good physicochemical properties for oral administration. The in vitro release profiles followed the Weibull model, with significant differences between the formulations containing the solubilized and the suspended compound. Furthermore, in vitro release data could be used to rank the observed in vivo bioavailability. The relative bioavailability of celecoxib from the solid lipid nanoparticles was 2.5- and 1.8-fold higher for the drug solubilized and suspended solid lipid nanoparticle formulation, respectively, when compared to the celecoxib reference. A significant difference was observed between the plasma concentration-time profiles and pharmacokinetic parameters for the three investigated formulations. Finally, this investigation displayed promising outcomes that both solubilized and suspended celecoxib in the lipid core of the solid lipid nanoparticles offers the potential to improve the compound's oral bioavailability and thereby reduce the dosing frequency.

Semisynthetic triterpenes led to the generation of selective antitrypanosomal lead compounds

Triterpenes α,β-amyrin are naturally occurring molecules that can serve as building blocks for synthesizing new chemical entities. This study synthesized acyl, carboxyesther, NSAID, and nitrogenous derivatives and evaluated their antimicrobial activity. A cyclodextrin complexation method was developed to improve the solubility of the derivatives. Of the 17 derivatives tested, five exhibited activity against Trypanosoma cruzi, T. brucei, Leishmania infantum, Candida albicans, Staphylococcus aureus, and Escherichia coli. The 9a/9b mixture showed weak activity against the parasites (IC₅₀ 24.45-40.32 μM). However, it showed no activity for the other microorganisms. Derivatives 14a/14b exhibited potent activity against T. cruzi (IC₅₀ 2.0 nM) in this tested concentration did not show activity to the other microorganisms and were not cytotoxic. Derivatives 15a/15b and 16a/16b demonstrated relevant activity against the parasites (IC₅₀ 2.24-5.44 μM), but were also cytotoxic. Derivatives 17a/17b showed low activity against the tested parasites (IC₅₀ 21.70-22.79 μM), but they were selective since they did not show activity against other microorganisms. In docking studies, in general, all derivatives showed complementarity with the CYP51 binding site of the trypanosomatid mainly by hydrophobic interactions; thus, it is not conclusive that the molecules act by inhibiting this enzyme. Our results showed that triterpenes derivatives with antitrypanosomal activity could be synthesized by an inexpensive and rapid method.

Targeting of sialoadhesin-expressing macrophages through antibody-conjugated (polyethylene glycol) poly(lactic-co-glycolic acid) nanoparticles

This research aims to evaluate different-sized nanoparticles consisting of (polyethylene glycol) (PEG) poly(lactic-co-glycolic acid) (PLGA), loaded with fluorescein isothiocyanate for nanoparticle uptake and intracellular fate in sialoadhesin-expressing macrophages, while being functionalized with anti-sialoadhesin antibody. Sialoadhesin is a macrophage-restricted receptor, expressed on certain populations of resident tissue macrophages, yet is also upregulated in some inflammatory conditions. The nanocarriers were characterized for nanoparticle size (84-319 nm), zeta potential, encapsulation efficiency, and in vitro dye release. Small (86 nm) antibody-functionalized PEG PLGA nanoparticles showed persisting benefit from sialoadhesin-targeting after 24 h compared to the control groups. For small (105 nm) PLGA nanoparticles, uptake rate was higher for antibody-conjugated nanoparticles, though the total amount of uptake was not enhanced after 24 h. For both plain and functionalized small-sized (PEG) PLGA nanoparticles, no co-localization between nanoparticles and (early/late) endosomes nor lysosomes could be observed after 1-, 4-, or 24-h incubation time. In conclusion, decorating (PEG) PLGA nanocarriers with anti-sialoadhesin antibodies positively impacts macrophage targeting, though it was found to be formulation-specific.

Selective targeting of skin pathobionts and inflammation with topically applied lactobacilli

Tailored skin microbiome modulation approaches with probiotics are highly challenging. Here, we show that lactobacilli are underestimated members of the skin microbiota. We select specific strains of nomadic lactobacilli for their functional applicability on the skin and capacity to inhibit growth and inflammation by skin pathobionts. The strains are formulated as microcapsules for topical formulations and tested in patients with mild-to-moderate acne. The selected lactobacilli are able to reduce inflammatory lesions in a pilot and placebo-controlled study. Daily application for 8 weeks is associated with an in vivo temporary modulation of the microbiome, including a reduction in relative abundance of staphylococci and Cutibacterium acnes, and an increase in lactobacilli. The reduction in inflammatory lesions is still apparent 4 weeks after the topical application of the lactobacilli ended, indicating a possible additional immunomodulatory effect. This study shows that carefully selected and formulated lactobacilli are a viable therapeutic option for common acne lesions.

A dynamically controlled anaerobic/aerobic granular sludge reactor efficiently treats brewery/bottling wastewater

This study investigated the application of a dynamic control strategy in an aerobic granular sludge (AGS) reactor treating real variable brewery/bottling wastewater. For 482 days, the anaerobic and aerobic reaction steps in a lab-scale AGS system were controlled dynamically. A pH-based control was used for the anaerobic step, and an oxygen uptake rate (OUR) based control for the aerobic step. Additionally, the effect of an elongated aerobic step, and the effect of the removal of the suspended solids from the influent, on AGS formation were also investigated. In comparison to a static operation, the dynamic operation resulted in similar reactor performance, related to effluent quality and the anaerobic dissolved organic carbon (DOC) uptake efficiency, while the organic loading rate was significantly higher. The removal of suspended solids from the influent by chemical coagulation with FeCl₃ turned hybrid floccular-granular sludge into fully granular sludge. The granulation coincided with a significant increase in the abundance of the glycogen-accumulating Candidatus Competibacter and an increase in the content of gel-forming EPS to respectively around 14% and 30%. In conclusion, this study showed the successful application of a dynamic control strategy based on common and low-cost sensors for AGS treatment of industrial wastewater.

Lactobacilli Have a Niche in the Human Nose

Although an increasing number of beneficial microbiome members are characterized for the human gut and vagina, beneficial microbes are underexplored for the human upper respiratory tract (URT). In this study, we demonstrate that taxa from the beneficial Lactobacillus genus complex are more prevalent in the healthy URT than in patients with chronic rhinosinusitis (CRS). Several URT-specific isolates are cultured, characterized, and further explored for their genetic and functional properties related to adaptation to the URT. Catalase genes are found in the identified lactobacilli, which is a unique feature within this mostly facultative anaerobic genus. Moreover, one of our isolated strains, Lactobacillus casei AMBR2, contains fimbriae that enable strong adherence to URT epithelium, inhibit the growth and virulence of several URT pathogens, and successfully colonize nasal epithelium of healthy volunteers. This study thus demonstrates that specific lactobacilli are adapted to the URT and could have a beneficial keystone function in this habitat.

Application of solid lipid nanoparticles as a long-term drug delivery platform for intramuscular and subcutaneous administration: In vitro and in vivo evaluation

The purpose of this work was to evaluate solid lipid nanoparticles (SLNs) as a long acting injectable drug delivery platform for intramuscular and subcutaneous administration. SLNs were developed with a low (unsaturated) and high (supersaturated) drug concentration at equivalent lipid doses. The impact of the drug loading as well as the administration route for the SLNs using two model compounds with different physicochemical properties were explored for their in vitro and in vivo performance. Results revealed that drug concentration had an influence on the particle size and entrapment efficiency of the SLNs and, therefore, indirectly an influence on the C_max/dose and AUC/dose after administration to rats. Furthermore, the in vitro drug release was compound specific, and linked to the affinity of the drug compounds towards the lipid matrix and release medium. The pharmacokinetic parameters resulted in an increased t_max, t_1/2 and mean residence time (MRT) for all formulations after intramuscular and subcutaneous dosing, when compared to intravenous administration. Whereas, the subcutaneous injections performed better for those parameters than the intramuscular injections, because of the higher blood perfusion in the muscles compared with the subcutaneous tissues. In conclusion, SLNs extend drug release, need to be optimized for each drug, and are appropriate carriers for the delivery of drugs that require a short-term sustained release in a timely manner.

Lacticaseibacillus casei AMBR2 Restores Airway Epithelial Integrity in Chronic Rhinosinusitis With Nasal Polyps

Purpose

A defective epithelial barrier has been demonstrated in chronic rhinosinusitis with nasal polyps (CRSwNP). Lactobacilli are shown to restore epithelial barrier defects in gastrointestinal disorders, but their effect on the airway epithelial barrier is unknown. In this study, hence, we evaluated whether the nasopharyngeal isolates Lacticaseibacillus casei AMBR2 and Latilactobacillus sakei AMBR8 could restore nasal epithelial barrier integrity in CRSwNP.

Methods

Ex vivo trans-epithelial tissue resistance and fluorescein isothiocyanate-dextran 4 kDa (FD4) permeability of nasal mucosal explants were measured. The relative abundance of lactobacilli in the maxillary sinus of CRSwNP patients was analyzed by amplicon sequencing of the V4 region of the 16S rRNA gene. The effect of spray-dried L. casei AMBR2 and L. sakei AMBR8 on epithelial integrity was investigated in vitro in primary nasal epithelial cells (pNECs) from healthy controls and patients with CRSwNP as well as in vivo in a murine model of interleukin (IL)-4 induced barrier dysfunction. The activation of Toll-like receptor 2 (TLR2) was explored in vitro by using polyclonal antibodies.

Results

Patients with CRSwNP had a defective epithelial barrier which positively correlated with the relative abundance of lactobacilli-specific amplicons in the maxillary sinus. L. casei AMBR2, but not L. sakei AMBR8, increased the trans-epithelial electrical resistance (TEER) of pNECs from CRSwNP patients in a time-dependent manner. Treatment of epithelial cells with L. casei AMBR2 promoted the tight junction proteins occludin and zonula occludens-1 reorganization. Furthermore, L. casei AMBR2 prevented IL-4-induced nasal permeability in vivo and in vitro. Finally, the beneficial effect of L. casei AMBR2 on nasal epithelial cells in vitro was TLR2-dependent as blocking TLR2 receptors prevented the increase in TEER.

Conclusions

A defective epithelial barrier in CRSwNP may be associated with a decrease in relative abundance of lactobacilli-specific amplicons. L. casei AMBR2 would restore nasal epithelial integrity and can be a novel therapeutic strategy for CRSwNP.

Cellular uptake of polymeric nanoparticles by bovine cumulus-oocyte complexes and their effect on in vitro developmental competence

Polymeric nanoparticles (NPs) are produced using bio-compatible and bio-degradable materials such as PLGA (Poly(lactic-co-glycolic acid)). This technology provides a valuable tool to deliver molecules to the subcellular level with a relatively low risk of cytotoxicity. However their use in the field of reproductive biotechnology is not yet scientifically substantiated. The aim of the present study was to test if PLGA NPs can be taken-up by cumulus-enclosed oocytes as a first step towards potential oocyte-targeted applications to enhance oocyte quality and fertility. We conducted a series of experiments using bovine in vitro oocyte maturation as a model to study FITC-conjugated PLGA internalization (using laser-scanning confocal microscopy) and the effect of some important physical (particle size) and chemical (conjugation with PEG) modifications. We show evidence that PLGA NPs can be taken-up by cumulus cells and to a less extent by the enclosed oocytes regardless of the NP size. The NP transfer to the oocyte appear to be transcellular (via cumulus cells and transzonal projections) and paracellular (via zona pellucida). The PLGA NPs were detected in the vicinity of the oocyte as quick as 2 h post-exposure in a protein-free medium and did not compromise cumulus cell viability nor subsequent early embryo development or embryo quality. These results suggest that PLGA NPs may have promising applications as carriers for drug or molecule delivery targeting cumulus cells and oocytes.

Probiotic nasal spray development by spray drying

The upper respiratory tract (URT) is the main entrance point for many viral and bacterial pathogens, and URT infections are among the most common infections in the world. Recent evidences by our own group and others imply the importance of lactobacilli as gatekeepers of a healthy URT. However, the benefits of putting health-promoting microbes or potential probiotics, such as these URT lactobacilli, in function of URT disease control and prevention is underestimated, among others because of the absence of adequate formulation modalities. Therefore, this study entails important aspects in probiotic nasal spray development with a novel URT-derived probiotic strain by spray drying. We report quantitative and qualitative analysis of several spray-dried formulations, i.e. powders for reconstitution, based on disaccharide or sugar alcohol combinations with a polymer, including their long-term stability. Four formulations with the highest survival of >10⁹ (Colony Forming Units) CFU/g after 28 weeks were further examined upon reconstitution which confirmed sufficiency of one bottle/dosage form during 7 days and rheological properties of shear-thinning. Tests also demonstrated maintained viability and cell morphology overall upon spraying through a nasal spray bottle in all 4 formulations. Lastly, application suitability in terms of high adherence to Calu-3 cells and antimicrobial activity against common URT pathogens was demonstrated and was not impacted neither by powder production process nor by spraying of reconstituted powder through a nasal spray device.

Improving cellular uptake and cytotoxicity of chitosan-coated poly(lactic-co-glycolic acid) nanoparticles in macrophages

Aim: This research aims to identify important formulation parameters for the enhancement of nanoparticle (NP) uptake and decreasing the cytotoxicity in macrophages. Materials & methods: Fluorescent poly(lactic-co-glycolic acid) (PLGA) nanocarriers were characterized for size distributions, zeta potential and encapsulation efficiency. Incubation time, size class, PLGA derivative and chitosan derivative were assessed for uptake kinetics and cell viability. Results: The major determining factor for enhancing cellular uptake were chitosan coatings, combined with acid-terminated PLGA and small NP size. Moreover, cytotoxicity was more favorable for small, chitosan glutamate-coated, acid-terminated PLGA NPs compared with its plain chitosan-coated counterparts. Conclusion: Chitosan glutamate has been shown to be a valuable alternative coating material for acid-terminated PLGA NPs to efficiently and safely target macrophages.

Correction to: Preparation and Characterization of Nanostructured Lipid Carriers for Improved Topical Drug Delivery: Evaluation in Cutaneous Leishmaniasis and Vaginal Candidiasis Animal Models

In the published manuscript, co-author Sarah Hendrickx name was misspelled and co-author Guy Caljon's last and first names were inadvertently switched.

Strain-specific differences in behaviour among Lacticaseibacillus rhamnosus cell wall mutants during direct compression

The human body harbours a large variety of microbial communities. It is already well-known that these communities play an important role in human health. Therefore, microbial imbalances can be responsible for several health disorders by different mechanisms. In recent years, probiotic bacteria have been increasingly applied to restore imbalances and stimulate microbiome functions such as immune modulation. Tablets are the dosage form of choice for oral probiotics. Nevertheless, a probiotic tablet with a sufficient amount of viable cells remains a challenge due to the stress of the compression process. Recent research demonstrated that the applied pressure and tableting properties play an important role in the survival of Lacticaseibacillus rhamnosus GG during direct compression. This study focused on the importance of the cell surface molecules in the protection of this prototype probiotic strain during direct compression. Spray-dried powders of L. rhamnosus GG and its exopolysaccharide-deficient mutant and lipoteichoic acid mutant were blended with two different filler-binders and compacted at various compression pressures. Under each tableting condition, the survival rate and tableting properties were analysed. The results demonstrated that the cell surface molecules play an important role in the behaviour of L. rhamnosus GG during direct compression. Specifically, the long, galactose-rich exopolysaccharides of L. rhamnosus served a protective shield during tablet production, promoting the survival rate of this probiotic strain. The D-alanylation of the lipoteichoic acids plays also an important role. When the D-alanyl ester content was completely absent, the survival rate was less affected by the tableting properties. Moreover, this research revealed that the sensitivity to the tableting properties is species and strain dependent.

Preparation and Characterization of Nanostructured Lipid Carriers for Improved Topical Drug Delivery: Evaluation in Cutaneous Leishmaniasis and Vaginal Candidiasis Animal Models

The present study aimed to develop, characterize and evaluate the amphotericin B-loaded nanostructured lipid carriers (AmB-NLCs) for topical treatment of cutaneous leishmaniasis (CL) and vulvovaginal candidiasis (VVC). AmB-NLCs were characterized for particle size, zeta potential, encapsulation efficiency and surface morphology. Prepared NLCs were also characterized for in vitro drug release, ex vivo skin permeation and deposition before evaluating their in vitro and in vivo efficacy. Cytotoxicity of NLCs was assessed on MRC-5 cells, whereas skin irritation potential was evaluated in vivo using rats. Significant accumulation of drug in to the skin supported the topical application potential of drug-loaded NLCs. Encapsulation of AmB in NLCs resulted in enhanced in vitro potency against promastigotes and intracellular amastigotes of L. major JISH 118 (IC₅₀ ± SEM = 0.02 ± 0.1 μM for both) compared with free drug (IC₅₀ ± SEM = 0.15 ± 0.2 & 0.14 ± 0.0, respectively). Similar improved potency of AmB-NLCs was also observed for other Leishmania and fungal strains compared with drug solution. Topical application of AmB-NLCs on L. major-infected BALB/c mice caused a significant reduction in parasite burden per mg of lesion (65 × 10⁸ ± 13) compared with the control group (> 167.8 × 10⁸ ± 11). Topical AmB-NLCs gel demonstrated superior efficacy in the vaginal C. albicans rat model for VVC as compared with plain AmB gel. Moreover, results of in vitro cytotoxicity assay and in vivo skin irritation test confirmed AmB-NLCs to be non-toxic and safe for topical use. In conclusion, NLCs may have promising potential as carrier for topical treatment of various conditions of skin and mucosa.

The use of 3 selected lactobacillary strains in vaginal probiotic gel for the treatment of acute Candida vaginitis: a proof-of-concept study

In vitro studies suggest that certain probiotic bacterial strains have potential activity against opportunistic infections such as Candida. There are few in vivo trials using probiotics as a single treatment for acute Candida vulvovaginitis (CV). In this open-label, proof-of-concept study, selected Lactobacillus strains were tested in women with acute Candida vaginitis. Twenty women diagnosed with proven, symptomatic CV were instructed to administer a vaginal probiotic gel with L. plantarum YUN-V2.0, L. pentosus YUN-V1.0 and L. rhamnosus YUN-S1.0 for 10 consecutive days. Vaginal rinsing fluid, vaginal culture swab and vaginal smear for fresh wet-mount microscopy were collected before and 7, 14 and 28 days after start of treatment. On average, participating women were 39 years old and had an history of 5 vaginal infections of which 95% was CV. Nine women (45%) completed the study without the need of rescue medication. Women who needed rescue treatment experienced twice as much Candida infections in the past. A negative correlation was found between the clinical composite score and the time to use rescue medication (R² = 0.127). Seventy-four per cent of participants found the study gel comfortable to use, and 42% of all women would use the tested gel again for this indication. Forty-five per cent of women were treated successfully for acute CV with a novel vaginal gel containing 3 selected Lactobacillus strains. Patients needing rescue treatment were suffering from more severe and long-standing disease. These results warrant for further testing of this new product, especially of its potential in cases with mild to moderate severity, as an adjuvant to antimycotics or as a preventive measure in women with recurrent vulvovaginal candidosis.

Importance of pressure plasticity during compression of probiotic tablet formulations

The usefulness, the high production rate and the cost effectiveness make tablets the dosage form of choice for oral probiotics. Nevertheless, probiotic bacteria undergo a lot of mechanical stress during tableting which causes damage to their cell wall and membrane and other bio-active components. This can lead to an inactivation of the probiotic bacteria and therefore in a failure of the probiotic therapy. To obtain a tablet with a sufficient amount of viable cells, research on the influence of formulation and process parameters on bacterial survival is essential. This study aimed to decipher tableting properties of the probiotic powder blends that have a major impact on survival rates. The powder blends consisted of the prototype probiotic strain Lactobacillus rhamnosus GG, a filler-binder and a suitable amount of lubricant. They were manufactured by direct compression at different compression pressures and tableting speeds. The tableting properties were analysed in detail by a 3-D modelling technique, which characterized normalized time, pressure and displacement simultaneously. The results of the 3-D modelling demonstrated the significant effect of the pressure plasticity (e) and the angle of rotation (ω) on the viability of L. rhamnosus GG during direct compression.

Impact of spray-drying on the pili of Lactobacillus rhamnosus GG

The preservation of the viability of microorganisms in probiotic formulations is the most important parameter ensuring the adequate concentration of live microorganisms at the time of administration. The formulation and processing techniques used to produce these probiotic formulations can influence the preservation of the microbial viability. However, it is also required that the bacteria maintain their key probiotic capacities during processing, formulation and shelf life. In this study, we investigated the impact of spray-drying on different cell wall properties of the model probiotic strain Lactobacillus rhamnosus GG, including its adherence to intestinal epithelial cells. The dltD gene knock-out mutant, L. rhamnosus GG CMPG5540, displaying modified cell wall lipoteichoic acids, showed significantly increased colony-forming units after spray-drying and subsequent storage under standard conditions compared to wild-type L. rhamnosus GG. In contrast, disruption of the biosynthesis of exopolysaccharides or pili expression did not impact survival. However, spray-drying did significantly affect the adherence capacity of L. rhamnosus GG. Scanning electron microscopy confirmed that the pili, key surface factors for adherence to intestinal cells and mucus, were sheared off during the spray-drying process. These data thus highlight that both the functionality and viability of probiotics should be assessed during the spray-drying process and subsequent storage.

Performance and stability of a dynamically controlled EBPR anaerobic/aerobic granular sludge reactor

Treatment of rapidly varying wastewaters in anaerobic/aerobic aerobic granular sludge (AGS) systems remains problematic. This study investigated AGS formation and the impact of varying COD and phosphorus concentrations on an enhanced biological phosphorus removal (EBPR) AGS SBR with a conductivity based anaerobic and OUR based aerobic dynamically controlled step. Phase 1 investigated the development of AGS. Phase 2 examined the flexibility of the dynamic control strategy and AGS efficiency while rapidly altering the influent composition. AGS was formed successfully in phase 1: the DV50 increased to 285 µm, and the SVI5 and SVI30 decreased to 51 and 40 ml/g respectively. In phase 2 the effluent COD and PO4-P concentration remained low at respectively 58 ± 27 mg/L and 0.53 ± 0.77 mg/L. With an anaerobic DOC uptake efficiency of 98.4 ± 0.9%.

Ultrasound-assisted extraction optimization and validation of an HPLC-DAD method for the quantification of polyphenols in leaf extracts of Cecropia species

Cecropia species are traditionally used in Latin American folk medicine and are available as food supplements with little information warranting their quality. The optimum conditions for the extraction of chlorogenic acid (CA), total flavonoids (TF) and flavonolignans (FL) from leaves of Cecropia species were determined using a fractional factorial design (FFD) and a central composite design (CCD). A reversed-phase high-performance liquid chromatographic method coupled to a diode array detector (HPLC-DAD) was validated for the quantification of CA, TF and FL, following the ICH guidelines. Quantitative and Principal Component Analysis (PCA) was also performed. The extraction-optimization methodology enabled us developing an appropriate extraction process with a time-efficient execution of experiments. The experimental values agreed with those predicted, thus indicating suitability of the proposed model. The validation parameters for all chemical markers of the quantification method were satisfactory. The results revealed that the method had excellent selectivity, linearity, precision (repeatability and intermediate precision were below than 2 and 5%, respectively) and accuracy (98–102%). The limits of detection and quantification were at nanogram per milliliter (ng/mL) level. In conclusion, the simultaneous quantification of chemical markers using the proposed method is an appropriate approach for species discrimination and quality evaluation of Cecropia sp.

Influence of mixed feeding rate in a conventional SBR on biological P-removal and granule stability while treating different industrial effluents

In this study, the influence of the anaerobic mixed feeding rate on granule stability and reactor performance in a conventional sequencing batch reactor (C-SBR) was investigated while treating various industrial wastewaters. A laboratory-scale SBR fed with malting wastewater rich in phosphorus was operated for approximately 250 days, which was divided into two periods: (I) mixed pulse feed and (II) prolonged mixed feed. Initially, no bio-P activity was observed. However, by lowering the feeding rate biological P-removal was rapidly established and no effect on the aerobic granular sludge (AGS) characteristics was observed. Additionally, to investigate the effect of the mixed feeding rate when treating an industrial effluent with low phosphorus content, i.e. brewery wastewater, a laboratory-scale reactor was operated for approximately 400 days applying different mixed feeding rates. Morphological and molecular analysis indicated that a low substrate concentration promoted the enrichment of anaerobic carbon storing filaments when fed with brewery wastewater. Findings suggest that a prolonged mixed feeding regime can be used as a tool to easily establish bio-P removal in a C-SBR system for the treatment of phosphorus-rich wastewaters. It should however be considered that under P-limiting conditions, enrichment of poly-P storing filaments may occur, possibly due to their higher substrate affinity under anaerobic conditions.

Elastic recovery of filler-binders to safeguard viability of Lactobacillus rhamnosus GG during direct compression

Tablets are increasingly explored as dosage form for oral probiotics, especially for applications such as pharyngitis and dental health. In such tablets, the dry form increases the stability and the shelf life of the product. In addition, the probiotic cells are entrapped in the tablet matrix, which protects them against the environmental factors in the human body. However, the development of a probiotic tablet with an adequate number of viable cells remains a challenge due to the stress of the compression process. The adverse conditions during production can damage the cells, which leads to a loss of viability and a failure of the therapy. This study aimed to investigate the effect of the compression behavior of filler-binders on the survival of Lactobacillus rhamnosus GG during tablet production. The probiotic tablets were manufactured by direct compression of a freeze-dried mixture of the model L. rhamnosus GG, a filler-binder and a suitable amount of lubricant. The compression behavior was determined by analyzing Heckel and force-displacement plots. The results demonstrated that the elastic recovery of the filler-binder during decompression played a protective role in bacterial survival, reducing the compression stress during manufacturing. Consequently, the bacterial cells were less damaged, which resulted in a higher survival rate and a better stability during long-term storage. In conclusion, the elastic recovery of a filler-binder showed to be an important key in safeguarding probiotic cells during direct compression and storage.

Formation of aerobic granular sludge and the influence of the pH on sludge characteristics in a SBR fed with brewery/bottling plant wastewater

A laboratory-scale sequencing batch reactor (SBR) was operated for 450 days to assess aerobic granule formation when treating brewery/bottling plant wastewater by consistent application of a feast/famine regime. The experiment was divided into three major periods according to the different operational conditions: (I) no pH control and strong fluctuations in organic loading rate (OLR) (1.18 ± 0.25 kgCOD·(m³·day)^-1), (II) pH control and aeration control strategy to reduce OLR fluctuations (1.45 ± 0.65 kgCOD·(m³·day)^-1) and (III) no pH control and stable OLR (1.42 ± 0.18 kgCOD·(m³·day)^-1). Aerobic granule formation was successful after 80 days and maintained during the subsequent 380 days. The aerobic granular sludge was characterized by SVI₅ and SVI₃₀ values below 60 mL.g^-1 and dominated by granular, dense structures. An oxygen uptake rate based aeration control strategy insured endogenous respiration at the end of the aerobic phase, resulting in stable SBR operation when the influent composition fluctuated. The quantitative polymerase chain reaction results show no significant enrichment of Accumulibacter or Competibacter during the granulation process. The 16S rRNA sequencing results indicate enrichment of other, possibly important species during aerobic granule formation while treating brewery wastewaters.

Interplay between Lactobacillus rhamnosus GG and Candida and the involvement of exopolysaccharides

A number of clinical studies have shown protective effects of lactobacilli against Candida species in the gastrointestinal tract, the urogenital tract and the oral cavity, while others did not show clear effects. Evidence on the mode of action of lactobacilli against Candida is also still lacking. In this study, the anti-Candida activity of the model probiotic strain Lactobacillus rhamnosus GG was explored in different assays to determine molecular interactions. We found that L. rhamnosus GG was able to interfere with Candida growth, morphogenesis and adhesion. These three aspects of Candida's physiology are all crucial to its opportunistic pathogenesis. In follow-up assays, we compared the activity of L. rhamnosus GG wild-type with its exopolysaccharide (EPS)-deficient mutant and purified EPS to evaluate the involvement of this outer carbohydrate layer. Our data demonstrate that purified EPS can both interfere with hyphal formation and adhesion to epithelial cells, which indicates that EPS is part of a combined molecular mechanism underlying the antihyphal and anti-adhesion mechanisms of L. rhamnosus GG.

Formation of aerobic granular sludge during the treatment of petrochemical wastewater

In this study, petrochemical wastewater from the port of Antwerp was used for the development of aerobic granular sludge. Two different reactor setups were used, (1) a completely aerated sequencing batch reactor (SBR_ae) with a feast/famine regime and (2) a sequencing batch reactor operated with an anaerobic feast/aerobic famine strategy (SBR_an). The seed sludge showed poor settling characteristics with a sludge volume index (SVI) of 285mL.gMLSS^-1 and a median particle size by volume of 86.0µm±1.9µm. In both reactors, granulation was reached after 30days with a SVI of 71mL.gMLSS^-1 and median granule size of 264.7µm in SBR_an and a SVI of 56mL.gMLSS^-1 and median granule size of 307.4µm in SBR_ae. The chemical oxygen demand (COD) and dissolved organic carbon (DOC) removal was similar in both reactors and above 95%. The anaerobic DOC uptake increased from 0.13% to 43.2% in 60days in SBR_an.

Optimisation of HPMC ophthalmic inserts with sustained release properties as a carrier for thermolabile therapeutics

A methodology was developed and optimised for the preparation of a new drug delivery system (DDS) with sustained release properties to allow ocular protein delivery and to limit destructive production steps during manufacturing. Elevated temperatures, shear forces and an oxidative environment should be avoided in order to prevent denaturation or oxidation of proteins. An aqueous HPMC solution was prepared using heat and casted into small semi-rod-shaped PVC blisters. The polymer solution was allowed to cool down and was partially dehydrated at room temperature. A drug solution containing glycerol, drug and water was subsequently added to rehydrate the partially dehydrated polymer matrix at a temperature of 2°C. Several parameters of the production process were varied to determine their influence on the release kinetics from HPMC inserts from three different molecules of different molecular weight. This production method was further optimised in order to shorten the rehydration time from weeks to days, while eliminating heat and shear forces on the selected drug molecules sodium fluorescein, lysozyme and albumin. Slow release kinetics were achieved for sodium fluorescein and lysozyme as model drug molecules. The higher molecular weight of albumin prevented a good penetration into the insert during the rehydration process resulting in predominantly burst release. The biocompatibility of a viscous HPMC solution was evaluated on SV40-human corneal epithelial cells with PrestoBlue^® and no cytotoxic effects were observed.

Comparative studies on osmosis based encapsulation of sodium diclofenac in porcine and outdated human erythrocyte ghosts

The objective of our study was to develop controlled drug delivery system based on erythrocyte ghosts for amphiphilic compound sodium diclofenac considering the differences between erythrocytes derived from two readily available materials - porcine slaughterhouse and outdated transfusion human blood. Starting erythrocytes, empty erythrocyte ghosts and diclofenac loaded ghosts were compared in terms of the encapsulation efficiency, drug releasing profiles, size distribution, surface charge, conductivity, surface roughness and morphology. The encapsulation of sodium diclofenac was performed by an osmosis based process - gradual hemolysis. During this process sodium diclofenac exerted mild and delayed antihemolytic effect and increased potassium efflux in porcine but not in outdated human erythrocytes. FTIR spectra revealed lack of any membrane lipid disorder and chemical reaction with sodium diclofenac in encapsulated ghosts. Outdated human erythrocyte ghosts with detected nanoscale damages and reduced ability to shrink had encapsulation efficiency of only 8%. On the other hand, porcine erythrocyte ghosts had encapsulation efficiency of 37% and relatively slow drug release rate. More preserved structure and functional properties of porcine erythrocytes related to their superior encapsulation and release performances, define them as more appropriate for the usage in sodium diclofenac encapsulation process.

Determination of five folate monoglutamates in rodent diets

A method for the quantitative determination of folates in rodent diets is very important for correct interpretation of folate intake during feeding trials, given the possible discrepancy between the actual folate concentration in the diet and that mentioned on the product sheet. Liquid chromatography tandem-mass spectrometry is the method of choice to differentiate and quantify the individual folate species present. This discrepancy may be accounted for by, e.g., inaccurate folic acid supplementation and/or the presence of endogenous reduced and substituted folates. We developed a method, validated based on FDA guidelines, that allows the measurement of added and endogenous folates by quantitative determination of 5 folate monoglutamates with linear ranges from 8 μg to 2 mg/kg feed. This information, combined with feed intake data, allows insight into the actual folate intake in animal feeding studies. The relevance of this method was illustrated by the analysis of several feed samples of varying composition, by the investigation of the effect of casein incorporation, and by evaluating the variability of the folate content between pellets and production batches.

Folate Profiling in Potato (Solanum tuberosum) Tubers by Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry

An ultrahigh-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the profiling of six folate species in potatoes. The calibration curves cover a wide, linear range (the lower and upper limits of quantitation range between 0.22-0.24 and 216.07-242.28 μg/100 g of fresh weight), allowing sensitive determination in small amounts of potato flesh. With a single exception, the acceptance criteria for intra- and interday precision and accuracy were met: for all quality controls, the percent relative standard deviation and the percent bias were lower than 15% (or 20% at the lower limit of quantitation). Application of the method on tubers at different stages of maturation demonstrated the large variability within a single variety: the folate content and polyglutamylation rate varied between 10.35 and 24.01 μg/100 g of fresh weight and between 4.96% and 60.49%, respectively. Additionally, the two-dimensional folate profiling of mature tubers demonstrated an increase in folate from center to peel, combined with a stable species distribution and polyglutamylation rate.

Use of ordered mesoporous silica to enhance the oral bioavailability of ezetimibe in dogs

The aim of this study was to investigate the bioavailability enhancement of the biopharmaceutics classification system class II compound ezetimibe loaded in ordered mesoporous silica (OMS) in dogs. The OMS was characterized as highly ordered mesoporous material with a narrow pore size distribution. Ezetimibe was loaded in OMS via incipient wetness impregnation to obtain a 20% (w/w) drug load, characterized by nitrogen adsorption and differential scanning calorimetry, and formulated in one capsule and two tablet formulations. Physicochemical characterization of loaded OMS indicated that ezetimibe molecules were molecularly deposited on the hydrophilic surface of the OMS. Two in vitro dissolution experiments were performed at 37°C in simulated gastric fluid with 0.1% sodium lauryl sulfate or Tween 80 to determine the drug release. All concepts were compared in vitro and in vivo with the commercially available tablet Ezetrol®. A dog study was designed to determine the oral bioavailability of ezetimibe capsules and tablets. The tablet preparations showed similar results to that of Ezetrol®. The capsule formulation demonstrated a faster absorption into the blood circulation, including a superior metabolization of ezetimibe into the active glucuronide conjugate. In vivo evaluation in dogs confirmed the improvement of ezetimibe absorption with the use of OMS as drug delivery technology.

Tablets Prepared by Single-Step Granulation/Tabletting: Interparticulate Binding Mechanism and Stability

The binding mechanism of tablets prepared by single-step granulation/tabletting (SSGT), a novel technique for the production of tablets, was evaluated. SSGT yielded hard tablets having a short disintegration time due to their porous, spongelike internal structure. Calculation of the interaction factor and electrical conductance tests confirmed the presence of solid bridges that provided a higher tensile strength to these compacts in comparison to tablets prepared by conventional tabletting techniques. At high relative humidity, moisture sorption and glass-to-rubber transition of the binder (polyvinylpyrrolidone), or condensation of moisture on the internal pore surface, reduced the tensile strength of the SSGT-manufactured tablets. Contrary to tablets prepared by granulation and compression, the SSGT tablets did not harden during storage under conditions of varying relative humidity (alternating the relative humidity every 24 hr between 33% and 75%).

Influence of the punch diameter and curvature on the yield pressure of MCC-compacts during Heckel analysis

The volume reduction behaviour of powders has been quantified by means of the 'in-die' yield pressure (YP) using Heckel analysis. However, because different YPs are reported for the same material, the experimental conditions influencing this material-constant were investigated. Silicified microcrystalline cellulose was compressed into flat-faced and convex tablets using a compaction simulator instrumented with load and displacement transducers. During compression, upper and lower punch force and displacement data were recorded and corrected for punch deformation. A symmetrical triangle wave compression profile was used and the instantaneous punch velocity was kept constant (5mm/s). Individual tablet height and weight were used for Heckel analysis. The influence of the 'effective compression pressure' (P(EFF)) (ranging from 10 to 350 MPa), punch diameter (PD) (4, 9.5 and 12 mm) and filling depth (FD) (4.5, 7.5 and 10.5mm) on YP was statistically evaluated using Response Surface Modelling software. A quadratic surface response equation, describing the relationship between P(EFF), PD, FD and YP, was proposed for concave (Adj R(2): 0.8424; S.D.: 14.60 MPa) and flat-faced (Adj R(2): 0.8409; S.D.: 4.49 MPa) punches. YP and tensile strength were mainly determined by P(EFF), irrespective of punch curvature. FD and PD had only a minor influence on the YP, although more pronounced for the concave punches. The method used resulted in reproducible P(EFF) and tensile strength values and the flat-faced tablets showed less weight variation. Flat-faced punches are preferred over punches with a concave surface when investigating the volume reduction behaviour of a powder by means of Heckel analysis and the experimental parameters should be reported.

Wax beads as cushioning agents during the compression of coated diltiazem pellets

Placebo particles were mixed with film-coated diltiazem pellets to evaluate them as cushioning agents during tabletting in order to protect the film coat from damage. The cushioning properties of alpha-lactose monohydrate granules, microcrystalline cellulose pellets and wax/starch beads were evaluated by comparing the dissolution profile of the coated pellets before and after compression (compression force 10 kN). Only the tablet formulations containing wax/starch beads provided protection to the film coat. However, the dissolution rate of tablets formulated with waxy maltodextrin/paraffinic wax placebo beads was too slow as the tablets did not disintegrate. Adding 50% (w/w) drum-dried corn starch/Explotab/paraffinic wax beads to the formulation was the optimal amount of cushioning beads to provide sufficient protection for the film coat and yield disintegrating tablets. Using a compression simulator, the effect of precompression force and compression time on the dissolution rate was found to be insignificant. The diametral crushing strength of tablets containing 50% (w/w) drum-dried corn starch/Explotab/paraffinic wax beads was about 25.0 N (+/-0.3 N), with a friability of 0.4% (+/-0.04%). This study demonstrates that adding deformable wax pellets minimizes the damage to film-coated pellets during compression.

Direct compression properties of melt-extruded isomalt

Isomalt, a sugar alcohol, was melt-extruded prior to compression in order to improve its tabletting properties. After fusion, crystalline isomalt was transformed into an amorphous form as shown by X-ray diffraction and differential scanning calorimetry (DSC). The tabletting properties of amorphous isomalt were dramatically improved. Mixtures formulated with paracetamol (50%) and extruded isomalt yielded hard tablets. However, extruded isomalt powder showed agglomeration problems due to recrystallization of the amorphous phase into a stable crystalline form in the presence of atmospheric moisture. The evolution of the moisture content correlated well with the compressibility data. The tablets made of extruded isomalt powder had a lower friability in comparison to the tablets formulated with non-extruded isomalt powder. Their disintegration was fast and a rapid dissolution rate was recorded. Extruded isomalt displayed excellent tabletting properties; however, further experiments should be conducted to delay or even prevent recrystallization of amorphous isomalt.

A validated HPLC method for the determination of thiazinamium methylsulphate in pharmaceutical preparations

The phenothiazine derivative thiazinamium methylsulphate is a drug with antihistaminic and anticholinergic properties, often used in some types of obstructive lung diseases. Because there is a lack of chromatographic data available for its determination, the objective of the present investigation was to develop a sensitive and rapid HPLC method for the quantitative estimation of thiazinamium methylsulphate in a pharmaceutical dosage form, applicable to routine analysis. The drug was chromatographed on a C18-reversed phase system applying a Licrocart column (LiChrospher 100 RP 18, 125 x 4 mm) with a mobile phase consisting of acetonitrile-water (3:7, v/v), employing as ion-pairing agent octanesulphonic acid sodium salt (20 mM) together with N,N-dimethyloctylamine (20 mM), adjusted to pH 3. Detection occurred at 254 nm. Propylparaben was used as an internal standard. The method was applied to solutions for intramuscular injection containing thiazinamium methylsulphate (65 mg/2 ml). Since little sample preparation is required, most analyses can be carried out within 15 min. The optimized method was validated and provided acceptable results with respect to linearity (r = 0.9999), precision and accuracy in the concentration range of 26-78 microg/ml. The proposed method is presently employed to investigate the stability of thiazinamium methylsulphate in solutions for intramuscular injection in the presence of anti-oxidizing agents.

Influence of drying temperature and granulation liquid viscosity on the inter- and intragranular drug migration in tray-dried granules and compacts

The influence of the drying temperature and granulation liquid viscosity on the inter- and intragranular migration of a poorly water-soluble compound in a granulation mass and in a compact was quantitatively assessed. The intergranular migration kinetics were investigated by evaluating the drug distribution at different drying-time intervals. The results were analyzed by use of two-factor, three-level, face-centered, central composite designs. Riboflavin was mixed with alpha-lactose monohydrate 90 M and granulated with distilled water, except for the viscosity experiments in which an aqueous polyvinylpyrrolidone (PVP) (Kollidon K90) solution was used. The wet granules were dried in a hot-air oven or compacted prior to drying. The drug concentration at different locations inside the granulated mass and the compacts after drying was determined spectrophotometrically and by use of diffuse light reflectance measurements. The riboflavin distribution in the granulation masses and in the compacts was characterized by drug-enriched outer layers and drug-depleted inner regions, indicating a strong migration phenomenon. It was clear that the drying temperature had no influence on the inter- and intragranular drug distribution. The intergranular migration was avoided using the PVP as a binder in the granulation liquid, whereas a minimal granulation liquid viscosity of 100 mPa.sec was necessary to avoid the intragranular migration. The diffuse light reflectance measurements can be used for the in-process control of granule samples containing low drug concentrations without the destruction of the samples.

Influence of chopper and mixer speeds and microwave power level during the high-shear granulation process on the final granule characteristics

Although microwave drying technology has been used extensively, detailed studies in the pharmaceutical field are necessary to model the different operational parameters involved in microwave drying in combination with the high-shear granulation processes. The implications of the chopper and the mixer speeds during the granulation step and the microwave power level during the drying step on the final granule characteristics were investigated. alpha-Lactose monohydrate and microcrystalline cellulose were granulated at three different mixer and chopper speeds in a laboratory-scale high-shear mixer (Mi-Mi-Pro) and dried at three microwave power levels. The dried granules were characterized by friability tests, particle size analysis, bulk and tapped density studies, and porosimetry. Neither the mixer speed nor the chopper speed had a significant influence on the granule friability, which was low for all batches produced. The selected materials and experimental conditions induced a very robust granulation process, but the granule size distribution was influenced by the microwave power level. The reciprocal relationship between the dust formation and the microwave power level was analyzed using a central composite factorial design. The amount of dust remained low in all batches, but it influenced some of the inherent density properties and the volume reduction behavior of the granulation mass. In almost all cases, the Carr index decreased slightly with increasing microwave power. The major granule characteristics were not changed when different mixer or chopper speeds were changed, although the mixer speed did alter the intragranular pore size distribution.

Characterization and evaluation of isomalt performance in direct compression

Isomalt is a sugar substitute with a wide range of potential pharmaceutical applications as a result of its physicochemical properties. Four grades of this material were evaluated for their physical characteristics. Only Palatinit(R) C and F exhibited potential characteristics for direct compression. As expected, the products required lubrification for tabletting. A level of 1% lubricant gave the best performance for Palatinit(R) C, the most compressible grade as shown by compaction profiles generated using a single-punch machine. However, its flow behaviour had to be improved by including 0.5% Aerosil(R) 200 as shown by tablet weight uniformity data. Further evaluation by Heckel analysis showed that isomalt exhibited plastic behaviour and underwent elastic recovery primary in the die. Its dilution potential was examined using powdered paracetamol. Acceptable tablets were produced up to 30% drug dilution, but the tensile strength values were reduced, disintegration time and friability increased as expected. Drug dissolution profiles showed a decreasing dissolution rate with the increase of compression force and drug concentration, but considerable improvement was noted when a disintegrant was included. The physical characteristics of the tablets were relatively stable after half a year storage at different humidities as a result of the low hygroscopicity of isomalt.

A comparison of the inter- and intragranular drug migration in tray- and freeze-dried granules and compacts

The influence of the drying process (tray- or freeze-drying), the granulation liquid viscosity, and the drying time during tray-drying on the inter- and intragranular migration of both a water-soluble and a poorly water-soluble compound in a granulation mass and in a compact were quantitatively assessed. Quinidine bisulfate (QBS) and riboflavin (RB) were mixed with a model excipient (glass microspheres) and granulated with an aqueous povidone solution. The drug concentration at different locations inside the granulated mass and in the compacts after drying was determined spectrophotometrically. The RB distribution in the compacts was more homogeneous than the QBS distribution. For both drugs it was clear that the intragranular migration decreased as the granulation liquid viscosity increased. The RB distribution in oven-dried granulation masses showed no migration problem, whereas the QBS samples were characterized by drug-enriched outer layers and drug-depleted inner regions, indicating a strong migration phenomenon. The drug distribution in all freeze-dried samples was homogeneous. A homogeneous distribution of a small-dosed water-soluble and a water-insoluble drug in granules and in compacts was obtained by the use of freeze-drying. The intragranular migration of QBS was prevented by the use of twice the amount of binder compared to that in RB compacts.