Liposome Suspensions Research Articles

Liposomal amikacin and Mycobacterium abscessus: intimate interactions inside eukaryotic cells.

Mycobacterium abscessus (Mabs), a rapidly growing Mycobacterium species, is considered an MDR organism. Among the standard antimicrobial multi-drug regimens against Mabs, amikacin is considered as one of the most effective. Parenteral amikacin, as a consequence of its inability to penetrate inside the cells, is only active against extracellular mycobacteria. The use of inhaled liposomal amikacin may yield improved intracellular efficacy by targeting Mabs inside the cells, while reducing its systemic toxicity. To evaluate the colocalization of an amikacin liposomal inhalation suspension (ALIS) with intracellular Mabs, and then to measure its intracellular anti-Mabs activity. We evaluated the colocalization of ALIS with Mabs in eukaryotic cells such as macrophages (THP-1 and J774.2) or pulmonary epithelial cells (BCi-NS1.1 and MucilAir), using a fluorescent ALIS and GFP-expressing Mabs, to test whether ALIS reaches intracellular Mabs. We then evaluated the intracellular anti-Mabs activity of ALIS inside macrophages using cfu and/or luminescence. Using confocal microscopy, we demonstrated fluorescent ALIS and GFP-Mabs colocalization in macrophages and epithelial cells. We also showed that ALIS was active against intracellular Mabs at a concentration of 32 to 64 mg/L, at 3 and 5 days post-infection. Finally, ALIS intracellular activity was confirmed when tested against 53 clinical Mabs isolates, showing intracellular growth reduction for nearly 80% of the isolates. Our experiments demonstrate the intracellular localization and intracellular contact between Mabs and ALIS, and antibacterial activity against intracellular Mabs, showing promise for its future use for Mabs pulmonary infections.

High skin permeation, deposition and whitening activity achieved by xanthan gum string vitamin c flexible liposomes for external application

For most external applied antioxidant whitening ingredients, effective stratum corneum breakthrough, epidermal penetration and dermal deposition are necessary premises for inhibition of melanin production and transfer occurring in stratum basale. Herein, xanthan gum was added into vitamin C-containing flexible liposome (Vc-L) suspension. The long polymer chain of xanthan gum string dispersed Vc-L together to gain a lotion (Vc-LX) for external application. In this study, the storage stability experiments demonstrated that the additional xanthan gum could improve the storage stability of Vc liposome suspension. The cumulative in vitro skin penetration and deposition of Vc-LX was found to significantly increase within 24 h in mouse skin, compared with those of the Vc aqueous solution and Vc conventional liposomes treated groups (***p < 0.001). Most importantly, in vivo skin whitening experiments gave that Vc-LX has better skin whitening activity (ΔL*) than marketed products (GARNIER® Vc377), Vc flexible liposomes, and Vc conventional liposomes. Moreover, in vitro cytotoxicity experiments and skin irritation experiments demonstrated that Vc-LX has good biosafety. Therefore, this study suggested that Vc-LX may be a promising local skin delivery system for water-soluble antioxidant ingredients.

Influence of impulse magnetic fields of extremely low frequencies on H2O2- and Fe2+-induced free radical lipid oxidation in liposomal suspensions

Background: For a long time, special attention in experimental biology and medicine is paid to free radical processes involving reactive oxygen species. In electromagnetic biology, the interest in free radical oxidation in biological membranes has increased significantly due to the discovery of spin mechanisms of magnetic fields on free radical processes. In the present day, these mechanisms are considered to be key in the processes of magnetoreception in living organisms. Liposomes, as the simplest models of biological membranes, are often used to study the primary mechanisms of action of different factors on the structural and functional properties of membranes. However, the influence of ecological significant extremely low-frequency magnetic fields on free radical oxidation in liposomal suspensions has not been studied enough. Objectives: The elucidation of the peculiarities of the influence of the extremely low frequency pulsed magnetic fields (ELF PMF) on H2O2- and Fe2+-induced peroxidation of natural phospholipids in liposomal suspensions. Materials and methods: The liposomal suspensions in phosphate buffer pH=7.4 were used. According to the literature and own results on light scattering the average diameter of liposomes was about 500Å. Ultra-weak chemiluminescence of liposomal suspensions was recorded using a device that operated in the mode of single photons counting. It consisted of a light-insulated cuvette unit where the test samples were placed, as well as a temperature sensor and a solenoid, which was used to create the PMF. Optical contact of the test samples with the photoelectron multiplier was carried out using a light guide. The recording system consisted of a broadband photomultiplier tube detector — FEU-130, which was at a temperature of –20°C. The pulse analyzer AI-256 was used to separate the useful signal that corresponded to the registration of single chemiluminescence light quanta. The voltage on the photomultiplier tube detector was applied in the range of current-voltage characteristics of this detector, in which a random voltage fluctuation had a minimal effect on the measurement of the useful signal. The number of light quanta that were recorded for defined time intervals characterized the overall intensity of the process of free radical oxidation of lipids in the experimental samples. The pulsed magnetic field was created using a solenoid coil located in the cuvette part. PMF was created using a serial generator G6-28. The magnetic field pulses were rectangular in shape with variable polarity for a period of oscillations. The induction of PMF was monitored using microteslameter G-79. The series of extremely low frequencies (5–80 Hz) and induction (5–500 μT) of PMF was chosen due to their environmental and physiological significance. Results: PMF of different frequencies with induction of 5 and 50 μT did not affect (p&gt;0.05) H2O2- and Fe2+-induced lipid oxidation in liposomal suspensions. Statistically significant changes (p&lt;0.05) were revealed only when liposomal suspensions were exposed to PMF with induction of 500 μT. It was found that the action of PMF with the frequency of 8 Hz 500 μT significantly inhibited H2O2-induced and enhanced Fe2+-induced chemiluminescence. This effect is associated with inhibition of the decomposition and with the accumulation of phospholipid hydroperoxides, which decompose and recombine in the presence of Fe2+ ions, which is accompanied by stronger chemiluminescence. The study of the dependence of the dynamics of the chemiluminescence intensity on the frequency of the PMF indicates the presence of a certain dependence of the effects in the range of up to 30 Hz. However, the inhibitory effect of PMF for the H2O2-induced oxidation phase is not always accompanied by a statistically significant increase in the amplitude of Fe2+-dependent light flash of chemiluminescence that indicates the general inhibitory effect of PMF at a certain frequency. Conclusions: PMF of extremely low frequencies statistically significantly affects the free radical oxidation in liposomal suspensions only at inductions exceeding several hundred microteslas. This indicates the effect of PMF on free radical processes for the conditions of the selected membrane model is realized mainly through spin interactions that determine the recombination of free radicals. The decrease of induction by one or two orders of magnitude, as well as increasing in frequency of the PMF above 50 Hz, leads to a decrease in the effectiveness of the influence of this physical factor on the intensity of lipid-free radical oxidation in liposomal suspensions. The most sensitive to the influence of ELF PMF is the phase of H2O2-induced free radical oxidation of lipids.

393 Young Scholar Award Talk: Investigation of Pain and Analgesic Strategies in Cattle Undergoing Painful Husbandry Procedures and Disease Conditions

Abstract Cattle are stoic by nature and have long been subject to evolutionary pressure to mask pain to avoid becoming prey. Quantifying pain via biomarkers allows researchers to capture changes that are not easily detected by the human eye. Negative public perception of routine husbandry practices such as dehorning and castration is growing, increasing the need for the development of practices to relieve pain and suffering in cattle. The objective was to quantify pain associated with induced bacterial pneumonia, scoop and hot-iron dehorning, surgical castration, and hot-iron branding, and to investigate analgesic effectiveness. Calves were experimentally inoculated with Mannheimia haemolytica, scoop or cautery dehorned, surgically castrated, or hot-iron branded. Outcome variables were collected at baseline and following husbandry procedures and included serum cortisol; infrared thermography (IRT); mechanical nociceptive threshold (MNT); substance P; kinematic gait analysis; a visual analog scale; chute defense and behavior scoring; clinical illness score; computerized lung score; average activity and rumination; prostaglandin E2 metabolite; plasma serum amyloid A and rectal temperature. Responses were analyzed using repeated measures with calf nested in treatment designated as a random effect, and treatment, time, and their interaction designated as fixed effects. A combination of reduced activity levels, decreased force on calves’ right front limb, and increased visual analog scale pain scores all support that bacterial pneumonia in cattle is painful (P ≤ 0.01). Differences in right front force were observed in calves challenged with M. haemolytica and treated with flunixin transdermal (96.5 kg) and those given a placebo (85.5 kg), indicating that flunixin transdermal may attenuate specific pain biomarkers in cattle with respiratory disease (P &amp;lt; 0.01). Administration of a bupivacaine liposome suspension block at the time of dehorning and castration was as effective at controlling pain as a multi-modal approach of lidocaine and meloxicam (as evidenced by treatment differences in MNT, cortisol and gait analysis (P ≤ 0.04)). Oral meloxicam administration at branding reduced IRT differences from the branding and control site and reduced lying bouts (P &amp;lt; 0.01). Breed and sex effects were observed across a wide range of biomarkers and should be investigated in future pain studies. The need for long-acting analgesic options for cattle that demonstrate pain alleviation across multiple biomarkers is apparent and would be beneficial to alleviating pain from routine husbandry procedures like dehorning, castration, and branding, as well as painful disease conditions such as bovine respiratory disease.

Application of the Ugi reaction for preparation of submicron capsules based on sugar beet pectin.

The Ugi four-component condensation in diluted liposomal suspensions was used to prepare pectin-based submicron capsules. A set of isocyanides and aldehydes was used to optimize the synthesis of capsule shells. Modified sugar beet pectin was selected as a natural polymer with pronounced surface activity to create a capsule shell. At first, liposomal composition was optimized in order to select suitable conditions for capsule formation. Then, the wide set of capsules constructed on modified sugar beet pectin scaffold has been synthesized. The choice was determined by level of substitution degree and possible chemical diversity of the modified surface. Detailed characterization of products has been performed for polysaccharide particles with liposomal core prepared with various processing parameters (concentration, cross-linking components, the density of linkage). The chemical structure, average size, polydispersity index, morphology, stability, and cytotoxicity of obtained particles have been investigated in dependence on the shell content. The obtained submicrometer cross-linked capsules (220-240nm) with controlled colloidal properties showed high stability and low toxicity. Thus, the proposed carriers have a great potential as sustained drug delivery systems for different administration routes.

Amikacin Liposomal Inhalation Suspension in the Treatment of Mycobacterium abscessus Lung Infection: A French Observational Experience.

Background Mycobacterium abscessus infections remain difficult to manage in both cystic fibrosis (CF) and non-CF patients and reported clinical outcomes are largely unsatisfactory. Clinical trial data are limited and no approved therapies are currently available for the management of M abscessus lung diseases. As an alternative, cohort studies may provide insightful information into the management of M abscessus pulmonary disease.MethodsBased on a retrospective observational cohort study, we investigated the safety and efficacy of amikacin liposome inhaled suspension (ALIS) as an adjunct to a standard antibiotic regimen for M abscessus lung infection in both CF and non-CF patients. We also assessed the association of patient drug compliance with culture conversion and clinical outcomes.ResultsTwenty-six patients had long-term follow-up data available. Culture conversion was achieved in 54% (14/26) of the patients with no difference between CF and non-CF patients after an average treatment duration of 10 months. Patient treatment compliance was significantly better in the converter group compared to nonconverters with an odds ratio of 44.78 associated with good compared to poor patient compliance. Overall, 9 patients (35%) experienced an adverse event that led to treatment discontinuation.ConclusionsALIS appears beneficial in both CF and non-CF populations with M abscessus lung disease.

Transverse abdominis plane injection of bupivacaine with dexmedetomidine or a bupivacaine liposomal suspension yielded lower pain scores and requirement for rescue analgesia in a controlled, randomized trial in dogs undergoing elective ovariohysterectomy.

To evaluate the duration and analgesic quality of bupivacaine mixed with dexmedetomidine (BUP-DEX) or bupivacaine liposome suspension (BLS) administered as a transverse abdominis plane (TAP) block, compared with a negative control (no TAP block; CTRL) in dogs. 26 mixed-breed shelter dogs undergoing elective ovariohysterectomy between January 28 and December 8, 2020. Each dog was randomly assigned to receive either an ultrasound-guided TAP block with either BUP-DEX or BLS or to receive no TAP block at time 0 after induction of general anesthesia. Superficial and abdominal wall pain scores were evaluated before time 0 and at 4, 6, 12, 24, 48, 72, and 96 hours later. Additionally, sedation scores and time to return of various behaviors, such as eating or drinking, were compared. The CTRL group had significantly greater pain scores than the BUP-DEX and BLS groups, but no differences were found between the BUP-DEX and BLS groups. Postoperatively, significantly more dogs needed rescue analgesia and the time to need it was shorter for the CTRL group, compared with the BUP-DEX or BLS groups. Additionally, the CTRL group had greater sedation scores than the other 2 groups. No significant differences were observed in any of the evaluated outcome variables such as eating or drinking. A TAP block appeared to provide adequate postoperative analgesia for abdominal surgery in the dogs of the present study undergoing elective ovariohysterectomy. The BLS TAP block did not appear to provide any extra benefit beyond what BUP-DEX TAP block added under these specific conditions.

Studies on the interactions of tiny amounts of common ionic surfactants with unsaturated phosphocholine lipid model membranes

In order to provide the fundamental information about the interactions of common anionic surfactants with the basic unsaturated phospholipids the influence of three cationic (dodecyltrimethylammonium bromide, DTAB; tetradecyltrimethylammonium bromide, TTAB and hexadecyltrimethylamonium bromide, CTAB) and one anionic (sodium dodecylsulfate, SDS) surfactants on the properties of the 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) layers was investigated. The studies proved that a tiny amount of the ionic surfactant added to the already synthesized liposome suspension is sufficient to change the zeta potential of the POPC and DOPC liposomes significantly. This impact increases with the surfactant concentration, the alkyl chain length of the surfactant and the degree of lipid saturation. Moreover, this effect is greater for the anionic surfactant than for the cationic one of the same alkyl chain length. The observed findings were confirmed in the course of the research carried out with the use of the corresponding Langmuir monolayers where the surface pressure – mean area isotherms, the compressibility modulus – surface pressure dependences, the monolayer penetration tests, the surface potential – mean molecular area isotherms and Brewster angle microscopy were discussed. It was found that the presence of the surfactants shifts the isotherms towards larger molecular area, to the higher extent for the SDS than DTAB. This effect increases with the increasing surfactant concentration in the subphase. Moreover, the investigated surfactants remain in the monolayer even at high surface pressure. Nevertheless, no effect on the morphology of the POPC and DOPC monolayers was detected from the BAM images. The surface potential and surface charge of the liposomes calculated on the basis of the zeta potential results reflected the interactions between the surfactant and the lipid layers.

Protection of hair color with pomegranate peel extract-loaded liposomal formulation: Preparation, characterization, and ex-vivo activity studies.

Pomegranate peel extract is known as a powerful antioxidant and due to preventing oxidation, it can reduce color change of dyed hair after washing. Liposomes are vesicular systems that include lipids and can form a film on hair fibers. Delivery system and active agent have a synergistic effect on protecting hair color and reducing dyeing frequency. This study aimed to prepare liposomes suspension as an innovative formulation of pomegranate peel extract to reduce hair color changing. Pomegranate peel extract-loaded liposomes were prepared with lipidic film hydration method. The characterizations of formulations (F1 and F2) were defined by several parameters. The pH, particle size, polydispersity index, zeta potential, microscopical image, loading capacity (LC), and encapsulation efficiency (EE) of formulations were determined. The antioxidant capacity of formulations and actives were tested. The effect of formulations on hair color change was shown with ex-vivo studies. The results showed that cholesterol influenced particle size, zeta potential, and antioxidant capacity. The particle sizes of formulations were 217.71 ± 6.74 nm and 577.5 ± 1.41 nm for F1 and F2, respectively. F2 formulation had better results for zeta potential (33.8mV) while F1 was neutral. Morphologic images confirmed vesicular structure or liposomes. The EE was found higher for F2 than F1 (F1: 57.14 and F2: 78.69). Antioxidant studies confirmed that active substance and the vesicular system had a synergistic effect on protection from oxidation. Selected formulation reduced hair color change as shown in ex-vivo tests. Pomegranate peel extract-loaded liposomes were designed for hair color protection. It was shown with this study that prepared formulations have a good color protection on hair fibers due to antioxidant properties of pomegranate peel extract and film forming effect of liposomal formulations. According to results, prepared liposomal formulations may serve as a good alternative for reducing dyeing frequency and protecting hair fibers.

Monitoring lipid phase transition temperatures using fluorescent probes and temperature-dependent fluorescence spectroscopy

The response of fluorescent dyes incorporated in multilamellar liposomes was evaluated for their applicability in monitoring thermal-induced changes in liposomes. Five fluorescent probes, diverse in polarity, lipophilicity, and consequently their position within the lipid multibilayers constituted from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), were used to record temperature-dependent fluorescence spectra of the liposomal suspensions. The responses of the dyes were analysed in a multivariate fashion to determine pre- and main phase transition temperatures of DPPC. Laurdan® and 1-chloro-9,10-bis(phenylethynyl)anthracene register both phase transitions, while 9,10-diphenylanthracene and 9,10-bis(phenylethynyl)anthracene report only pretransition. According to the differential scanning calorimetry (DSC) measurements, all suspensions display both phase transitions that resemble DSC curve of pure DPPC. The positions of the dyes within the bilayers were determined by molecular dynamics simulations.

Block duration is substantially longer with a liposomal suspension of bupivacaine than with 0.5% bupivacaine HCl potentiated with dexmedetomidine following an ultrasound-guided sciatic nerve block in Beagles

To compare the duration of bupivacaine liposome suspension in the dog with that of bupivacaine and dexmedetomidine following a perineural injection. 8 healthy Beagles. The left sciatic nerve of each dog was randomly assigned to an ultrasound-guided perineural injection with either bupivacaine liposome suspension (BLS) or with 0.5% bupivacaine with dexmedetomidine (1 µg/mL) (BUP-DEX). The contralateral nerve was assigned to the alternate agent. The sensory, motor, and proprioceptive functions were evaluated before the injection (baseline) and at 4, 10, 24, 48, 72, and 96 hours. The block in 1 limb in the BLS treatment appeared to have failed (data set excluded). The motor scores of 2 individuals could not be evaluated leaving 5 limbs to evaluate in the BLS treatment and 6 in the BUP-DEX. A total of 6 out of 7 limbs in the BLS achieved a complete sensory block. In 3 out of 5 treatments with BLS, motor block was only partial and in 2 not apparent at all. Proprioceptive block was partial in 5 out of 7 dogs in the BLS treatment. All functions were still completely obliterated at 10 hours in 6 cases in treatment BUP-DEX. All functions were restored in all cases by 96 and 24 hours after administration of BLS and BUP-DEX, respectively. The blockade characteristics of bupivacaine liposome suspension were effective and long lasting. Motor and proprioceptive deficits may be inconsistent over time.

A low-cost, flexible extruder for liposomes synthesis and application for Murrayafoline A delivery for cancer treatment.

Liposomal encapsulation is a drug delivery strategy with many advantages, such as improved bioavailability, ability to carry large drug loads, as well as controllability and specificity towards various targeted diseased tissues. Currently, most preparation techniques require an additional extrusion or filtering step to obtain monodisperse liposomes with the size of less than 100nm. In this study, a compact liposome extruder was designed at a cost of $4.00 and used to synthesize liposome suspensions with defined particle size and high homogeneity for Murrayafoline A (Mu-A) loading and release. The synthesized MuA-loaded liposomes displayed a biphasic drug release and remained stable under the storage condition of 4°C. They also significantly reduced the viability of HepG2 cells in the cancer spheroids by 25%. The low-cost, flexible liposome extruder would allow the researchers to study liposomes and their applications in a cost-effective manner.

1 Awardee Talk: Investigation of Pain and Analgesic Strategies in Cattle Undergoing Painful Husbandry Procedures and Disease Conditions

Abstract Negative public perception of routine husbandry practices such as dehorning and castration is growing, increasing the need for the development of practices to relieve pain and suffering in livestock. The objective was to quantify pain associated with induced bacterial pneumonia, hot-iron dehorning, surgical castration, and hot-iron branding, and to investigate analgesic effectiveness. Calves were experimentally inoculated with Mannheimia haemolytica, cautery dehorned, surgically castrated, or hot-iron branded. Outcome variables were collected at baseline and following husbandry procedures and included serum cortisol; infrared thermography (IRT); mechanical nociceptive threshold (MNT); substance P; kinematic gait analysis; a visual analog scale (VAS); chute defense and behavior scoring; clinical illness score; computerized lung score; average activity and rumination; prostaglandin E2 metabolite (PGEM); plasma serum amyloid A and rectal temperature. Reduced activity levels, decreased force on calves’ right front limb, and increased VAS scores all support that bacterial pneumonia in cattle is painful. Differences in right front force were observed in calves challenged with M. haemolytica and treated with flunixin transdermal and those given a placebo, indicating that flunixin transdermal may attenuate specific pain biomarkers in cattle with respiratory disease. Pain from cautery dehorning and surgical castration can last up to 120 h post-dehorning indicated by changes in IRT, MNT, PGEM and gait analysis. Administration of bupivacaine liposome suspension as a local anesthetic block at the time of dehorning and castration was as effective at controlling pain as a multi-modal approach of lidocaine and meloxicam. Changes in IRT, MNT, lying time, step count, visual analog scale score and wound scoring all support that hot-iron branding cattle is painful. Oral meloxicam administration reduced IRT differences from the branding and control site and reduced lying bouts. Breed and sex effects were observed across a wide range of biomarkers. The need for long-acting analgesic options for cattle that demonstrate pain alleviation across multiple biomarkers is apparent and would be beneficial to alleviating pain and suffering.

LARGE MULTILAMELLAR NEUTRAL LIPOSOMES FORM A STABLE LAYER ON ARTICULAR CARTILAGE SURFACE UNDER EX-VIVO PHYSIOLOGICAL COMPRESSION

Purpose: Surface active phospholipids (SAPLs) including dipalmitoylphosphatidylcholine (DPPC) play a vital role in the natural boundary lubricant of articular cartilage and are degraded during progression of osteoarthritis (OA). MM-II is a suspension of large multilamellar neutral liposomes composed of two phospholipids, dimyristoylphosphatidylcholine (DMPC) and DPPC which is administered via intra-articular (IA) administration and is currently in a phase 2b clinical study. In a series of ex-vivo cartilage-on-cartilage friction and wear tests, MM-II liposomes were shown to lubricate cartilage and reduce hence friction and wear.

Versatile Encapsulation and Synthesis of Potent Liposomes by Thermal Equilibration.

The wide-scale use of liposomal delivery systems is challenged by difficulties in obtaining potent liposomal suspensions. Passive and active loading strategies have been proposed to formulate drug encapsulated liposomes but are limited by low efficiencies (passive) or high drug specificities (active). Here, we present an efficient and universal loading strategy for synthesizing therapeutic liposomes. Integrating a thermal equilibration technique with our unique liposome synthesis approach, co-loaded targeting nanovesicles can be engineered in a scalable manner with potencies 200-fold higher than typical passive encapsulation techniques. We demonstrate this capability through simultaneous co-loading of hydrophilic and hydrophobic small molecules and targeted delivery of liposomal Doxorubicin to metastatic breast cancer cell line MDA-MB-231. Molecular dynamic simulations are used to explain interactions between Doxorubicin and liposome membrane during thermal equilibration. By addressing the existing challenges, we have developed an unparalleled approach that will facilitate the formulation of novel theranostic and pharmaceutical strategies.

Comparison of lidocaine alone or in combination with a local nerve block of ethanol, bupivacaine liposome suspension, or oral meloxicam to extend analgesia after scoop dehorning in Holstein calves

The American Veterinary Medical Association recommends the use of practices that reduce or eliminate pain and discomfort associated with dehorning. Identification of an effective, long-acting local anesthetic that is practical for producers to implement and reduces pain from dehorning would benefit animal welfare. Thirty-two Holstein bulls and heifers were enrolled. The objective of this study was to compare the efficacy and duration of activity of bupivacaine liposome suspension (BUP; n = 8), ethanol (ETH; n = 8), or meloxicam (LID + MEL; n = 8) co-administered with lidocaine compared with lidocaine only (LID; n = 8), and to quantify their effect on pain biomarkers and behaviors after scoop dehorning with cauterization in approximately 20-wk-old calves. Outcome variables collected included infrared thermography (IRT), mechanical nociceptive threshold (MNT), visual analog scale (VAS) scoring, and blood sampling for serum cortisol and prostaglandin E2 metabolites (PGEM). There was evidence of a sex effect for MNT, with bulls demonstrating a higher threshold (13.74 kgf) compared with heifers (12.12 kgf). There was a treatment by time interaction for cortisol concentrations (ng/mL). At 2 h, the BUP group had higher cortisol values (17.32 ng/mL) than the LID + MEL group (3.10 ng/mL). Heifers also had higher mean cortisol values (13.88 ng/mL) compared with bulls (6.96 ng/mL). There was a treatment by time interaction for PGEM concentration. Calves in the LID + MEL group had lower PGEM values at 4 and 8 h (10.23 and 9.12 pg/mL) than at −24, 0, and 0.5 h (20.38, 27.27, and 22.59 pg/mL, respectively). At 4 h, the LID + MEL group had lower PGEM concentrations (10.23 pg/mL) than the ETH group (27.08 pg/mL). At 8 h, the LID + MEL group had lower PGEM concentrations (9.12 pg/mL) than both the ETH and BUP groups (24.80 and 20.52 pg/mL). Thus, LID + MEL reduced cortisol and prostaglandin metabolite concentrations more effectively than ETH + LID or BUP + LID administered as a local infiltration and cornual block, respectively, before scoop dehorning followed by cauterization. The treatments administered in the present study did not seem to extend the duration of analgesia beyond the currently recommended multimodal approach, including local anesthesia and systemic analgesia such as lidocaine and meloxicam. Evidence from the current study suggests that sex influences pain biomarkers such as nociceptive threshold and cortisol concentration, with males having a higher nociceptive threshold and lower cortisol responses.

Phase transitions of liposomes: when light meets heat

Phase transitions of liposomes are normally studied by differential scanning calorimetry. A suspension of liposomes is subjected to an increase (decrease) of temperature and when heat is absorbed (released), the liposomes transit from a gel (liquid) to a liquid (gel) phase. This endothermic (exothermic) process takes place at a temperature called the melting temperature T m, which is distinctive of the type of lipids forming the vesicles. The vesicles, though, also modify their size in the transition. Indeed, the thickness of the membranes decreases (increases) because carbon tails misalign (align). Concomitant with the modifications in the membrane thickness, the diameter (D) of the liposomes changes too. Therefore, when they are inspected by light, the scattered signal carries information from such dilatation (contraction) process. We performed careful experiments using dynamic light scattering as a function of temperature to detect the size changes of different liposomes. Gaussian fits of the derivatives of the D vs T curves coincide within 1% with thermograms, which hints to the possibility of performing thermodynamic studies of lipid systems employing light.

Anti-inflammatory effects of free and liposome-encapsulated Algerian thermal waters in RAW 264.7 macrophages

The main objectives of this work were to formulate liposomes encapsulating highly mineralized thermal waters (TWs) and to study anti-inflammatory effect of free and encapsulated thermal waters on RAW 264.7 macrophage cells stimulated with lipopolysaccharide (LPS). TWs-loaded conventional and deformable liposomes (TWs-Lip and TWs-DLip) were prepared by sonication and extrusion, respectively. They were considered for their vesicle size, zeta potential, entrapment efficiency, physical stability and in vitro anti-inflammatory effect. Formulated liposome suspensions have a low polydispersity and nanometric size range with zeta potential values close to zero. The vesicle size was stable for 30 days. Entrapment efficiency of TWs was above 90% in conventional liposomes and 70% in deformable liposomes. Pretreatment of LPS-stimulated murine macrophages, with free and liposome-encapsulated TWs, resulted in a significant reduction in nitric oxide (NO) production and modulated tumor necrosis factor-α (TNF-α) production suggesting an anti-inflammatory effect which was even more striking with TWs-Lip and TWs-DLip. Liposome formulations may offer a suitable approach for transdermal delivery of TWs, indicated in inflammatory skin diseases.

Effect of bupivacaine liposome suspension administered as a local anesthetic block on indicators of pain and distress during and after surgical castration in dairy calves

Castration is a routine procedure performed on beef and dairy operations in the United States. All methods of castration cause behavioral, physiologic, and neuroendocrine changes associated with pain. The American Veterinary Medical Association and the American Association of Bovine Practitioners recommend that anesthesia and analgesia be administered during castration. The objective of this study was to evaluate the effectiveness of bupivacaine liposome suspension, a novel, long-acting, local anesthetic formulation administered as a nerve block at castration. The authors chose to investigate this novel formulation as an alternative to the current industry standards using lidocaine nerve blocks alone or in combination with meloxicam. Thirty male Holstein calves, 16 to 20 wk of age, were enrolled and randomly assigned to one of the four treatment groups prior to surgical castration: 1) bupivacaine liposome suspension block + oral placebo (BUP), 2) lidocaine block + oral placebo (LID), 3) lidocaine block + oral meloxicam (1 mg/kg) (LID + MEL), and 4) saline block + oral placebo (CON). Biomarkers were collected at −24 h and from 0 to 120 h post-castration and included infrared thermography, pressure mat gait analysis, chute defense and behavior scoring (pain and activity), and blood sampling for serum cortisol and prostaglandin E2 metabolites (PGEMs). Responses were analyzed using repeated measures, with calf nested in treatment as a random effect, and treatment, time, and their interaction designated as fixed effects. The results from pressure mat gait analysis show that the CON had a shorter front limb stance time from baseline (−8.73%; 95% confidence interval [CI]: −24.84% to 7.37%) compared with BUP and LID + MEL (>5.70%; 95% CI: −22.91% to 23.79%) (P < 0.03). The CON tended to have an increase in front limb force from baseline (6.31%; 95% CI: −1.79% to 14.41%) compared with BUP, LID, and LID + MEL (<−5.06%; 95% CI: −14.22% to 0.95%) (P < 0.04). The CON displayed higher counts of hunched standing (2.00; 95% CI: 1.68 to 2.32) compared with LID + MEL (1.43; 95% CI: 1.13 to 1.72) (P = 0.05). The CON had higher cortisol concentrations at 24 h (7.70 ng/mL; 95% CI: 1.52 to 13.87 ng/mL) relative to BUP (3.11 ng/mL; 95% CI: −2.56 to 8.79 ng/mL) (P = 0.002). At 4 and 24 h, LID + MEL had lower PGEM concentrations from baseline (−32.42% and −47.84%; 95% CI: −78.45% to −1.80%) compared with CON (27.86% and 47.63%; 95% CI: 7.49% to 82.98%) (P < 0.02). The administration of bupivacaine liposome suspension as a local anesthetic block at the time of castration was as effective at controlling pain as a multimodal approach of lidocaine and meloxicam.

Physical-Chemical Characterization of Bilayer Membranes Derived from (±) α-Tocopherol-Based Gemini Lipids and Their Interaction with Phosphatidylcholine Bilayers and Lipoplex Formation with Plasmid DNA.

Membrane formation and aggregation properties of two series of (±) α-tocopherol-based cationic gemini lipids without and with hydroxyl functionalities at the headgroup region (TnS n = 3, 4, 5, 6, 8, and 12; THnS n = 4, 5, 6, 8, and 12) with varying polymethylene spacer lengths were investigated extensively while comparing with the corresponding properties of the monomeric counterparts (TM and THM). Liposomal suspensions of each cationic lipid were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), zeta potential measurements, and small-angle X-ray diffraction studies. The length of the spacer and the presence of hydroxyl functionalities at the headgroup region strongly contribute to the aggregation behavior of these gemini lipids in water. The interaction of each tocopherol lipid with a model phospholipid, 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC)-derived vesicles, was thoroughly examined by differential scanning calorimetry (DSC) and 1,6-diphenyl-1,3,5-hexatriene (DPH)-doped fluorescence anisotropy measurements. The binding efficiency of the cationic tocopherol liposomes with plasmid DNA (pDNA) was followed by an ethidium bromide (EB) exclusion assay and zeta potential measurements, whereas negatively charged micellar sodium dodecyl sulfate (SDS)-mediated release of the pDNA from various preformed pDNA-liposomal complexes (lipoplex) was studied by an ethidium bromide (EB) reintercalation assay. The structural transformation of pDNA upon complexation with liposome was characterized using circular dichroism (CD) spectroscopic measurements. Gemini lipid-pDNA interactions depend on both the presence of hydroxyl functionalities at the headgroups and the length of the spacer chain between the headgroups. Succinctly, we performed a detailed physical-chemical characterization of the membranes formed from cationic monomeric and gemini lipids bearing tocopherol as their hydrophobic backbone and describe the role of inserting the -OH group at the headgroup of such lipids.