In Vitro and In Vivo Efficacy of Topical Dosage Forms Containing Self-Nanoemulsifying Drug Delivery System Loaded with Curcumin.

The external use of curcumin is rare, although it can be a valuable active ingredient in the treatment of certain inflammatory diseases. The aim of our experimental work was to formulate topical dosage forms containing curcumin for the treatment of atopic dermatitis. Curcumin has extremely poor solubility and bioavailability, so we have tried to increase it with the usage of self-emulsifying drug delivery systems. Creams and gels were formulated using penetration-enhancing surfactants and gelling agents. The release of the drug from the vehicle and its penetration through the membrane were determined using a Franz diffusion cell. An MTT cytotoxicity and in vitro antioxidant assays were performed on HaCaT cell line. The in vivo anti-inflammatory effect of the preparations was tested by measuring rat paw edema. In addition, we examined the degree of inflammation induced by UV radiation after pretreatment with the cream and the gel on rats. For the gels containing SNEDDS, the highest penetration was measured after half an hour, while for the cream, it took one hour to reach the maximum concentration. The gel containing Pemulen TR-1 showed the highest drug release. It was determined that the curcumin-containing preparations can be safely applied on the skin and have antioxidant effects. The animal experiments have proven the effectiveness of curcumin-containing topical preparations.

Formulation and characterization of pramipexole containing buccal films for using in Parkinson's disease.

Parkinson's disease (PD) is neurodegenerative chronic illness which affects primarily the elderly over 45 years of age. The symptoms can be various, both non-motor and motor symptoms can appear. The biggest problem in the treatment of the disease is the difficulty in swallowing for the patients. However, buccal patches can solve this problem because the patients do not have to swallow the dosage form, and during application, the API can absorb from the area of the buccal mucosa quickly without causing a foreign body sensation. In our present study, we focused on the development of buccal polymer films with pramipexole dihydrochloride (PR). Films with different compositions were formulated and their mechanical properties and chemical interactions were investigated. The biocompatibility of the film compositions was examined on the TR146 buccal cell line. The permeation of PR was also monitored across the TR146 human cell line. It can be stated that the plasticizer can enhance the thickness and the breaking hardness of the films, while not decreasing their mucoadhesivity significantly. All formulations proved to have cell viability higher than 87%. Finally, we found the best composition (3% SA+1% GLY-PR-Sample1) which can be applied on the buccal mucosa in the treatment of PD.

Formulation and Characterization of Mucoadhesive Polymeric Films Containing Extracts of Taraxaci Folium and Matricariae Flos.

Taraxaci folium and Matricariae flos plant extracts contain a wide range of bioactive compounds with antioxidant and anti-inflammatory effects. The aim of the study was to evaluate the phytochemical and antioxidant profile of the two plant extracts to obtain a mucoadhesive polymeric film with beneficial properties in acute gingivitis. The chemical composition of the two plant extracts was determined by high-performance liquid chromatography coupled with mass spectrometry. To establish a favourable ratio in the combination of the two extracts, the antioxidant capacity was determined by the method of reduction of copper ions Cu2+ from neocuprein and by reduction of the compound 1.1-diphenyl-2-2picril-hydrazyl. Following preliminary analysis, we selected the plant mixture Taraxaci folium/matricariae flos in the ratio of 1:2 (m/m), having an antioxidant capacity of 83.92% ± 0.02 reduction of free nitrogen radical of 1.1-diphenyl-2-2picril-hydrazyl reagent. Subsequently, bioadhesive films of 0.2 mm thickness were obtained using various concentrations of polymer and plant extract. The mucoadhesive films obtained were homogeneous and flexible, with pH ranging from 6.634 to 7.016 and active ingredient release capacity ranging from 85.94-89.52%. Based on in vitro analysis, the film containing 5% polymer and 10% plant extract was selected for in vivo study. The study involved 50 patients undergoing professional oral hygiene followed by a 7-day treatment with the chosen mucoadhesive polymeric film. The study showed that the film used helped accelerate the healing of acute gingivitis after treatment, with anti-inflammatory and protective action.

Effect of Molecular Weight on the Dissolution Profiles of PEG Solid Dispersions Containing Ketoprofen.

Solid dispersions are typically binary systems with a hydrophilic matrix polymer and a lipophilic active substance. During formulation, the drug undergoes a crystalline to amorphous phase transition, which leads to a supersaturated solution providing enhanced bioavailability. The interaction of the active substance and the polymer is unique and influences the level of supersaturation. We aimed to investigate the relationship between low molecular weight polyethylene glycol derivates PEG 1000, 1500, and 2000 and ketoprofen regarding the effect of molecular weight. The physicochemical properties of solid dispersions prepared with hot melt homogenization and their respective physical mixtures were investigated with Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy techniques. A phase solubility study was carried out in hydrochloric acid media which showed no difference between the three polymers, but the dissolution curves differed considerably. PEG 1000 had higher percentage of released drug than PEG 1500 and 2000, which had similar results. These results indicate that when multiple low molecular weight PEGs are suitable as matrix polymers of solid dispersions, the molecular weight has only limited impact on physicochemical characteristics and interactions and further investigation is needed to select the most applicable candidate.

Recent Options and Techniques to Assess Improved Bioavailability: In Vitro and Ex Vivo Methods.

Bioavailability assessment in the development phase of a drug product is vital to reveal the disadvantageous properties of the substance and the possible technological interventions. However, in vivo pharmacokinetic studies provide strong evidence for drug approval applications. Human and animal studies must be designed on the basis of preliminary biorelevant experiments in vitro and ex vivo. In this article, the authors have reviewed the recent methods and techniques from the last decade that are in use for assessing the bioavailability of drug molecules and the effects of technological modifications and drug delivery systems. Four main administration routes were selected: oral, transdermal, ocular, and nasal or inhalation. Three levels of methodologies were screened for each category: in vitro techniques with artificial membranes; cell culture, including monocultures and co-cultures; and finally, experiments where tissue or organ samples were used. Reproducibility, predictability, and level of acceptance by the regulatory organizations are summarized for the readers.

Enhanced Antioxidant and Anti-Inflammatory Effects of Self-Nano and Microemulsifying Drug Delivery Systems Containing Curcumin.

Turmeric has been used for decades for its antioxidant and anti-inflammatory effect, which is due to an active ingredient isolated from the plant, called curcumin. However, the extremely poor water-solubility of curcumin often limits the bioavailability of the drug. The aim of our experimental work was to improve the solubility and thus bioavailability of curcumin by developing self-nano/microemulsifying drug delivery systems (SN/MEDDS). Labrasol and Cremophor RH 40 as nonionic surfactants, Transcutol P as co-surfactant and isopropyl myristate as the oily phase were used during the formulation. The average droplet size of SN/MEDDS containing curcumin was between 32 and 405 nm. It was found that the higher oil content resulted in larger particle size. The drug loading efficiency was between 93.11% and 99.12% and all formulations were thermodynamically stable. The curcumin release was studied at pH 6.8, and the release efficiency ranged between 57.3% and 80.9% after 180 min. The results of the MTT cytotoxicity assay on human keratinocyte cells (HaCaT) and colorectal adenocarcinoma cells (Caco-2) showed that the curcumin-containing preparations were non-cytotoxic at 5 w/v%. According to the results of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide dismutase (SOD) assays, SNEDDS showed significantly higher antioxidant activity. The anti-inflammatory effect of the SN/MEDDS was screened by enzyme-linked immunosorbent assay (ELISA). SNEDDS formulated with Labrasol as surfactant, reduced tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1ß) levels below 60% at a concentration of 10 w/w%. Our results verified the promising use of SN/MEDDS for the delivery of curcumin. This study demonstrates that the SN/MEDDS could be promising alternatives for the formulation of poorly soluble lipophilic compounds with low bioavailability.

Stability, Permeability and Cytotoxicity of Buccal Films in Allergy Treatment.

Oral mucoadhesive systems, such as polymer films, are among innovative pharmaceutical products. These systems can be applied in swallowing problems and can also be used in geriatrics and paediatrics. In our earlier work, we successfully formulated buccal mucoadhesive polymer films, which contained cetirizine-hydrochloride (CTZ) as the API. The present study focused on investigating the stability and permeability of the prepared films. The stability of the films was studied with an accelerated stability test. During the stability test, thickness, breaking hardness and in vitro mucoadhesivity were analysed. Furthermore, the interactions were studied with FT-IR spectroscopy, and the changes in the amount of the API were also monitored. Cytotoxicity and cell line permeability studies were carried out on TR 146 buccal cells. Compositions that can preserve more than 85% of the API after 6 months were found. Most of the compositions had a high cell viability of more than 50%. Citric acid (CA) decreased the stability and reduced every physical parameter of the films. However, cell line studies showed that the permeability of the films was enhanced. In our work, we successfully formulated CTZ-containing buccal films with adequate stability, high cell viability and appropriate absorption properties.

Physiological and transcriptional profiling of surfactin exerted antifungal effect against Candida albicans.

Given the risk of Candida albicans overgrowth in the gut, novel complementary therapies should be developed to reduce fungal dominancy. This study highlights the antifungal characteristics of a Bacillus subtilis-derived secondary metabolite, surfactin with high potential against C. albicans. Surfactin inhibited the growth of C. albicans following a 1-hour exposure, in addition to reduced adhesion and morphogenesis. Specifically, surfactin did not affect the level of reactive oxygen species but increased the level of reduced glutathione. Surprisingly, ethanol production was increased following 2 h of surfactin exposure. Surfactin treatment caused a significant reduction in intracellular iron, manganese and zinc content compared to control cells, whereas the level of copper was not affected. Alongside these physiological properties, surfactin also enhanced fluconazole efficacy. To gain detailed insights into the surfactin-related effects on C. albicans, genome-wide gene transcription analysis was performed. Surfactin treatment resulted in 1390 differentially expressed genes according to total transcriptome sequencing (RNA-Seq). Of these, 773 and 617 genes with at least a 1.5-fold increase or decrease in transcription, respectively, were selected for detailed investigation. Several genes involved in morphogenesis or related to metabolism (e.g., glycolysis, ethanol and fatty acid biosynthesis) were down-regulated. Moreover, surfactin decreased the expression of ERG1, ERG3, ERG9, ERG10 and ERG11 involved in ergosterol synthesis, whereas genes associated with ribosome biogenesis and iron metabolism and drug transport-related genes were up-regulated. Our data demonstrate that surfactin significantly influences the physiology and gene transcription of C. albicans, and could contribute to the development of a novel innovative complementary therapy.

Topical Dosage Formulation of Lyophilized Philadelphus coronarius L. Leaf and Flower: Antimicrobial, Antioxidant and Anti-Inflammatory Assessment of the Plant.

Philadelphus coronarius is a versatile plant and its use in folk medicine has a long tradition; however, scientifically, the medical utilization of the herb is a less explored research field. The aim of our study was to identify and determine the quantity of the bioactive compounds of both the leaf and the flower and prepare a lyophilized product of them, from which medical ointments were formulated, since the topical application of P. coronarius has also not been studied. In vitro drug release, texture analysis and biocompatibility experiments were carried out, as well as the investigation of microbiological, antioxidant and anti-inflammatory properties. According to our results the composition and the selected excipients of the ointments have a great impact on the drug release, texture and bioavailability of the preparation. During the microbiological testing, the P. coronarius leaf was effective against Escherichia coli and Staphylococcus aureus, but it did not significantly decrease IL-4 production when it was tested on HaCaT cells. P. coronarius is a promising herb, and its topical application in antimicrobial therapy can be a useful addition to modern medical therapy.

Comparative Investigation of Cellular Effects of Polyethylene Glycol (PEG) Derivatives.

Nowadays, polyethylene glycols referred to as PEGs are widely used in cosmetics, consumer care products, and the pharmaceutical industry. Their advantageous properties such as chemical stability, low immunogenicity, and high tolerability explain why PEGs are applied in many fields of pharmaceutical formulations including parenteral, topical, ophthalmic, oral, and rectal preparations and also in modern drug delivery systems. Given their extensive use, they are considered a well-known group of chemicals. However, the number of large-scale comparative studies involving multiple PEGs of wide molecular weight range is low, as in most cases biological effects are estimated upon molecular weight. The aim of this publication was to study the action of PEGs on Caco-2 cells and G. mellonella larvae and to calculate the correlation of these effects with molecular weight and osmolality. Eleven PEGs of different molecular weight were used in our experiments: PEG 200, PEG 300, PEG 400, PEG 600, PEG 1000, PEG 1500, PEG 4000, PEG 8000, PEG 10,000, 12,000, and PEG 20,000. The investigated cellular effects included cytotoxicity (MTT and Neutral Red assays, flow cytometry with propidium iodide and annexin V) and autophagy. The osmolality of different molecular weight PEGs with various concentrations was measured by a vapor pressure osmometer OSMOMAT 070 and G. mellonella larvae were injected with the solutions of PEGs. Sorbitol was used as controls of the same osmolality. Statistical correlation was calculated to describe the average molecular weight dependence of the different measured effects. Osmolality, the cytotoxicity assays, flow cytometry data, and larvae mortality had significant correlation with the structure of the PEGs, while autophagosome formation and the proportion of early apoptotic cells showed no statistical correlation. Overall, it must be noted that PEGs must be tested individually for biological effects as not all effects can be estimated by the average molecular weight.

Virulence Factors and in-Host Selection on Phenotypes in Infectious Probiotic Yeast Isolates (Saccharomyces 'boulardii').

Saccharomyces yeast probiotics (S. 'boulardii') have long been applied in the treatment of several gastrointestinal conditions. Despite their widespread use, they are rare opportunistic pathogens responsible for a high proportion of Saccharomyces mycosis cases. The potential virulence attributes of S. 'boulardii' as well as its interactions with the human immune system have been studied, however, no information is available on how these yeasts may change due to in-host evolution. To fill this gap, we compared the general phenotypic characteristics, cell morphology, virulence factors, epithelial and immunological interactions, and pathogenicity of four probiotic product samples, two mycosis, and eight non-mycosis samples of S. 'boulardii'. We assessed the characteristics related to major steps of yeast infections. Mycosis and non-mycosis isolates both displayed novel characters when compared to the product isolates, but in the case of most virulence factors and in pathogenicity, differences were negligible or, surprisingly, the yeasts from products showed elevated levels. No isolates inflicted considerable damage to the epithelial model or bore the hallmarks of immune evasion. Our results show that strains in probiotic products possess characteristics that enable them to act as pathogens upon permissive conditions, and their entry into the bloodstream is not due to active mechanisms but depends on the host. Survival in the host is dependent on yeast phenotypic characteristics which may change in many ways once they start evolving in the host. These facts call attention to the shortcomings of virulence phenotyping in yeast research, and the need for a more thorough assessment of probiotic use.

Formulation of Creams Containing Spirulina Platensis Powder with Different Nonionic Surfactants for the Treatment of Acne Vulgaris.

Natural products used in the treatment of acne vulgaris may be promising alternative therapies with fewer side effects and without antibiotic resistance. The objective of this study was to formulate creams containing Spirulina (Arthrospira) platensis to be used in acne therapy. Spirulina platensis belongs to the group of micro algae and contains valuable active ingredients. The aim was to select the appropriate nonionic surfactants for the formulations in order to enhance the diffusion of the active substance and to certify the antioxidant and antibacterial activity of Spirulina platensis-containing creams. Lyophilized Spirulina platensis powder (SPP) was dissolved in Transcutol HP (TC) and different types of nonionic surfactants (Polysorbate 60 (P60), Cremophor A6:A25 (CR) (1:1), Tefose 63 (TFS), or sucrose ester SP 70 (SP70)) were incorporated in creams as emulsifying agents. The drug release was evaluated by the Franz diffusion method and biocompatibility was tested on HaCaT cells. In vitro antioxidant assays were also performed, and superoxide dismutase (SOD) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays were executed. Antimicrobial activities of the selected compositions were checked against Staphylococcus aureus (S. aureus) and Cutibacteriumacnes (C. acnes) (formerly Propionibacterium acnes) with the broth microdilution method. Formulations containing SP 70 surfactant with TC showed the most favorable dissolution profiles and were found to be nontoxic. This composition also showed significant increase in free radical scavenger activity compared to the blank sample and the highest SOD enzyme activity was also detected after treatment with the cream samples. In antibacterial studies, significant differences were observed between the treated and control groups after an incubation time of 6 h.

Comparative biocompatibility and antimicrobial studies of sorbic acid derivates.

Nowadays, the sorbates are the third largest group of antimicrobial preservatives in food and pharmaceutical industries, following the parabens and benzoates whose safety is questioned by recent publications. A disadvantage of sorbates is their pH dependence, as their antimicrobial effect is greatly reduced in alkaline environment. The main, widely used sorbate derivatives are sorbic acid and potassium sorbate, no sorbic acid esters are involved in current industrial application. We aimed to test whether the esters of sorbic acid are capable to extend the antimicrobial spectrum of the original molecule while maintaining its advantageous biocompatibility profile. A comparative biocompatibility study of different derivatives (sorbic acid, potassium sorbate, isopropyl sorbate and ethyl sorbate) was carried out. In vitro cell viability assays of MTT (2-(4,5-dimethyl-2-thiazolyl)-3,5-diphenyl-2H-tetrazolium bromide), Neutral Red (3-amino-7-dimethylamino-2-methylphenazine hydrochloride) and flow cytometry with propidium iodide and annexin were performed on Caco-2 cells. In case of in vivo toxicity study, G. mellonella larvae were injected with different concentrations of the test compounds. Time-kill tests were executed on reference strains of C. albicans, E. coli, and S. aureus. According to the MTT-assay, the IC50 values were the following: ethyl sorbate, sorbic acid <0.045% w/w, isopropyl sorbate 0.32% w/w, potassium sorbate >0.75% w/w, while Neutral Red values were >0.75% w/w for the esters and potassium sorbate and 0.66% w/w for sorbic acid. Flow cytometry results indicated the higher cell damage in case of isopropyl sorbate. However, the cytotoxic results of isopropyl sorbate, in vivo toxicity study on G. mellonella larvae did not show significant mortality. It was found, that the antimicrobial properties of isopropyl sorbate were outstanding compared to sorbic acid and potassium sorbate. These results indicate, that the use of sorbate esters can be advantageous, hence, further toxicity studies are needed to prove their safety.

Physiological and Transcriptional Responses of Candida parapsilosis to Exogenous Tyrosol.

Tyrosol plays a key role in fungal morphogenesis and biofilm development. Also, it has a remarkable antifungal effect at supraphysiological concentrations. However, the background of the antifungal effect remains unknown, especially in the case of non-albicans Candida species such as Candida parapsilosis We examined the effect of tyrosol on growth, adhesion, redox homeostasis, virulence, as well as fluconazole susceptibility. To gain further insights into the physiological consequences of tyrosol treatment, we also determined genome-wide gene expression changes using transcriptome sequencing (RNA-Seq). A concentration of 15 mM tyrosol caused significant growth inhibition within 2 h of the addition of tyrosol, while the adhesion of yeast cells was not affected. Tyrosol increased the production of reactive oxygen species remarkably, as revealed by a dichlorofluorescein test, and it was associated with elevated superoxide dismutase, glutathione peroxidase, and catalase activities. The interaction between fluconazole and tyrosol was antagonistic. Tyrosol exposure resulted in 261 and 181 differentially expressed genes with at least a 1.5-fold increase or decrease in expression, respectively, which were selected for further study. Genes involved in ribosome biogenesis showed downregulation, while genes related to the oxidative stress response and ethanol fermentation were upregulated. In addition, tyrosol treatment upregulated the expression of efflux pump genes, including MDR1 and CDR1, and downregulated the expression of the FAD2 and FAD3 virulence genes involved in desaturated fatty acid formation. Our data demonstrate that exogenous tyrosol significantly affects the physiology and gene expression of C. parapsilosis, which could contribute to the development of treatments targeting quorum sensing in the future.IMPORTANCECandida-secreted quorum-sensing molecules (i.e., farnesol and tyrosol) are key regulators in fungal physiology, which induce phenotypic adaptations, including morphological changes, altered biofilm formation, and synchronized expression of virulence factors. Moreover, they have a remarkable antifungal activity at supraphysiological concentrations. Limited data are available concerning the tyrosol-induced molecular and physiological effects on non-albicans Candida species such as C. parapsilosis In addition, the background of the previously observed antifungal effect caused by tyrosol remains unknown. This study reveals that tyrosol exposure enhanced the oxidative stress response and the expression of efflux pump genes, while it inhibited growth and ribosome biogenesis as well as several virulence-related genes. Metabolism was changed toward glycolysis and ethanol fermentation. Furthermore, the initial adherence was not influenced significantly in the presence of tyrosol. Our results provide several potential explanations for the previously observed antifungal effect.

Physico-chemical characterization of self-emulsifying drug delivery systems.

Self-emulsifying drug delivery systems (SEDDS) are regarded as a potential implement for oral delivery of water insoluble APIs to overcome their poor and irregular bioavailability. The correlation between the physicochemical parameters and the behavior of self-emulsifying drug delivery systems was established. The objective of this study was to summarize these physicochemical factors characterized SEDDS. Determination of self-emulsification process and ternary phase diagram are the basis of preparations. The position of APIs in SEDDS inclusion can be determined by dye solubilisation test. The end point of self-emulsification was controlled by turbimetric evaluation. Optimisation of droplet size and zeta potential are crucial parameters because they can influence i.e. the dissolution rate of APIs and the stability of SEDDS. Besides the basic methods in the characterization of SEDDS such as dispersibility tests, turbidimetric evaluation, viscosity tests, determinations with complex instruments such as photon correlation spectroscopy or dynamic light-scattering, electro kinetic potential measurement, non-destructive spectroscopic techniques (LFDS, FTIR, RS) and various microscopic techniques (SEM, PLM, EDS) has also been described.

Interaction between Different Pharmaceutical Excipients in Liquid Dosage Forms-Assessment of Cytotoxicity and Antimicrobial Activity.

Nowadays, the safety of parabens as pharmaceutical preservatives is debated. Recent studies investigated their interference with the oestrogen receptors, nevertheless their carcinogenic activity was also proved. That was the reason why the re-evaluation of the biocompatibility and antimicrobial activity of parabens is required using modern investigation methods. We aimed to test the cytotoxic, antifungal and antibacterial effect of parabens on Caco-2 cells, C. albicans, C. parapsilosis, C. glabrata, E. coli, P. aeruginosa and S. aureus. Two complex systems (glycerol-Polysorbate 20; ethanol-Capryol PGMC™) were formulated to study-with the MTT-assay and microdilution method, respectively-how other excipients may modify the biocompatibility and antimicrobial effect of parabens. In the case of cytotoxicity, the toxicity of these two systems was highly influenced by co-solvents and surfactants. The fungi and bacteria had significantly different resistance in the formulations and in some cases the excipients could highly modify the effectiveness of parabens both in an agonistic and in a counteractive way. These results indicate that with appropriate selection, non-preservative excipients can contribute to the antimicrobial safety of the products, thus they may decrease the required preservative concentration.

Self-Nanoemulsifying Drug Delivery Systems Containing Plantago lanceolata-An Assessment of Their Antioxidant and Antiinflammatory Effects.

The most important components of Plantago lanceolata L. leaves are catalpol, aucubin, and acteoside (=verbascoside). These bioactive compounds possess different pharmacological effects: anti-inflammatory, antioxidant, antineoplastic, and hepatoprotective. The aim of this study was to protect Plantago lanceolata extract from hydrolysis and to improve its antioxidant effect using self-nano-emulsifying drug delivery systems (SNEDDS). Eight SNEDDS compositions were prepared, and their physical properties, in vitro cytotoxicity, and in vivo AST/ALT values were investigated. MTT cell viability assay was performed on Caco-2 cells. The well-diluted samples (200 to 1000-fold dilutions) proved to be non-cytotoxic. The acute administration of PL-SNEDDS compositions resulted in minor changes in hepatic markers (AST, ALT), except for compositions 4 and 8 due to their high Transcutol contents (80%). The non-toxic compositions showed a significant increase in free radical scavenger activity measured by the DPPH test compared to the blank SNEDDS. An indirect dissolution test was performed, based on the result of the DPPH antioxidant assay; the dissolution profiles of Plantago lancolata extract were statistically different from each SNEDDS. The anti-inflammatory effect of PL-SNEDDS compositions was confirmed by the ear inflammation test. For the complete examination period, all compositions decreased ear edema as compared to the positive (untreated) control. It can be concluded that PL-SNEDDS compositions could be used to deliver active natural compounds in a stable, efficient, and safe manner.

Carrier-envelope phase changes in the focal region: propagation effects measured by spectral interferometry.

Spectral interferometric measurements are presented that show how wave propagation affects the carrier-envelope phase (CEP) of an ultrashort pulse in the focal region and results in variations that are different from the Gouy phase shift. Wavelength-dependent properties of the input beam are investigated and are seen to influence how the CEP is altered. The measured CEP changes show characteristics similar to the variations predicted by theory.

Unexpected insensitivity of the cholinergic motor responses to morphine in the human small intestine.

BACKGROUND/AIMS: morphine is known to inhibit cholinergic contractions of the guinea pig small intestine. This has been compared to the human small intestinal innervated longitudinal muscle in the current study. METHODS: cholinergic primary contractions of human small intestinal longitudinal strips were evoked by electrical field stimulation (EFS; 0.5- 5 Hz in the presence of purinergic and nitrergic blockers or 5 Hz without pretreatment) and recorded isotonically in organ bath experiments. Guinea pig small intestinal segments were also studied. RESULTS AND CONCLUSION: neurogenic cholinergic contractions of human preparations were unaffected by morphine (1, 2 or 10 micromol/l). Longitudinal contractions of the guinea pig ileum were concentration-dependently suppressed by morphine (0.1-10 micromol/l). It is concluded that myenteric neurons supplying the longitudinal muscle of the human small intestine are much less sensitive to morphine than those of the guinea pig.