Amphiphilic Cyclodextrin Nanoparticles as Delivery System for Idebenone: A Preformulation Study

Idebenone (IDE), a synthetic short-chain analogue of coenzyme Q10, is a potent antioxidant able to prevent lipid peroxidation and stimulate nerve growth factor. Due to these properties, IDE could potentially be active towards cerebral disorders, but its poor water solubility limits its clinical application. Octanoyl-β-cyclodextrin is an amphiphilic cyclodextrin (ACyD8) bearing, on average, ten octanoyl substituents able to self-assemble in aqueous solutions, forming various typologies of supramolecular nanoassemblies. Here, we developed nanoparticles based on ACyD8 (ACyD8-NPs) for the potential intranasal administration of IDE to treat neurological disorders, such as Alzheimer’s Disease. Nanoparticles were prepared using the nanoprecipitation method and were characterized for their size, zeta potential and morphology. STEM images showed spherical particles, with smooth surfaces and sizes of about 100 nm, suitable for the proposed therapeutical aim. The ACyD8-NPs effectively loaded IDE, showing a high encapsulation efficiency and drug loading percentage. To evaluate the host/guest interaction, UV-vis titration, mono- and two-dimensional NMR analyses, and molecular modeling studies were performed. IDE showed a high affinity for the ACyD8 cavity, forming a 1:1 inclusion complex with a high association constant. A biphasic and sustained release of IDE was observed from the ACyD8-NPs, and, after a burst effect of about 40%, the release was prolonged over 10 days. In vitro studies confirmed the lack of toxicity of the IDE/ACyD8-NPs on neuronal SH-SY5Y cells, and they demonstrated their antioxidant effect upon H2O2 exposure, as a general source of ROS.

The Effect of α-, β- and γ-Cyclodextrin on Wheat Dough and Bread Properties

Cyclodextrins (CDs) are cyclic oligosaccharides that have found widespread application in numerous fields. CDs have revealed a number of various health benefits, making them potentially useful food supplements and nutraceuticals. In this study, the impact of α-, β-, and γ-CD at different concentrations (up to 8% of the flour weight) on the wheat dough and bread properties were investigated. The impact on dough properties was assessed by alveograph analysis, and it was found that especially β-CD affected the viscoelastic properties. This behavior correlates well with a direct interaction of the CDs with the proteins of the gluten network. The impact on bread volume and bread staling was also assessed. The bread volume was in general not significantly affected by the addition of up to 4% CD, except for 4% α-CD, which slightly increased the bread volume. Larger concentrations of CDs lead to decreasing bread volumes. Bread staling was investigated by texture analysis and low field nuclear magnetic resonance spectroscopy (LF-NMR) measurements, and no effect of the addition of CDs on the staling was observed. Up to 4% CD can, therefore, be added to wheat bread with only minor effects on the dough and bread properties.

Enhanced Cellular Uptake Of Phenamil Through Inclusion Complex With Histidine Functionalized β-Cyclodextrin As Penetrative Osteoinductive Agent

Background

Phenamil (PH) is a small molecule that induces bone formation through upregulation of the TRB3 gene in the bone-regeneration process. β-Cyclodextrins (βCDs) with hydrophilic surfaces and a relatively hydrophobic cavity can form inclusion complexes with primarily hydrophobic small molecules such as PH, and increase their apparent solubility and dissolution rate. The hydrophilic surface of βCDs prevents their interaction with the hydrophobic lipids of the cell membrane for penetration. Therefore, binding of penetrative groups, such as lysine, arginine, and histidine (His), to βCDs for cell penetration is required.

Aim

The aim of this study was to investigate the effect of His-conjugated βCD on cellular uptake of PH for bone differentiation.

Methods

In this study, His-βCDs were synthesized and used to prepare an inclusion complex of His-βCD-PH. A hydroxypropyl-βCD-PH (HP-βCD-PH) inclusion complex for increasing PH solubility without a penetrative group was prepared for comparison. 3-D geometry of βCD derivatives and PH-inclusion complexes was investigated by Fourier-transform infrared spectroscopy and molecular docking. Alizarin red staining and real-time PCR were performed to compare bone differentiation of His-βCD-PH and HP-βCD-PH.

Results

The results suggested that the benzene ring of PH was inserted into the wide side of both His-βCD and HP-βCD. Alizarin red staining at 14 days postculture in the presence of His-βCD-PH at total concentration of 50 μM for PH showed that bone-matrix mineralization increased significantly compared with free PH and HP-βCD-PH. Real-time PCR confirmed this result, and showed gene expression increased significantly (OPN 1.84-fold, OCN 1.69-fold) when stem cells were cultured with His-βCD-PH.

Conclusion

The overall results indicated that His-βCD-PH is a promising carrier for osteoinductive PH with possible penetration ability and sustained release that reduces BMP2 consumption for differentiation of mesenchymal stem cells to bone tissue.

Fabricating β-cyclodextrin based pH-responsive nanotheranostics as a programmable polymeric nanocapsule for simultaneous diagnosis and therapy

Background

Fabrication of a smart drug delivery system that could dramatically increase the efficiency of chemotherapeutic drugs and reduce the side effects is still a challenge for pharmaceutical researchers. By the emergence of nanotechnology, a huge window was opened towards this goal, and a wide type of nanocarriers were introduced for delivering the chemotherapeutic to the cancer cells, among them are cyclodextrins with the ability to host different types of hydrophobic bioactive molecules through inclusion complexation process.

Aim

The aim of this study is to design and fabricate a pH-responsive theranostic nanocapsule based on cyclodextrin supramolecular nano-structure.

Materials and methods

This nanostructure contains iron oxide nanoparticles in the core surrounded with three polymeric layers including polymeric β-cyclodextrin, polyacrylic acid conjugated to sulfadiazine, and polyethylenimine functionalized with β-cyclodextrin. Sulfadiazine is a pH-responsive hydrophobic component capable of making inclusion complex with β-cyclodextrin available in the first and third layers. Doxorubicin, as an anti-cancer drug model, was chosen and the drug loading and release pattern were determined at normal and acidic pH. Moreover, the biocompatibility of the nanocapsule (with/without drug component) was examined using different techniques such as MTT assay, complement activation, coagulation assay, and hemolysis.

Results

The results revealed the successful preparation of a spherical nanocapsule with mean size 43±1.5 nm and negatively charge of −43 mV that show 160% loading efficacy. Moreover, the nanocapsule has an on/off switching release pattern in response to pH that leads to drug released in low acidic pH. The results of the biocompatibility tests indicated that this nano drug delivery system had no effect on blood and immune components while it could affect cancer cells even at very low concentrations (0.3 μg mL⁻¹).

Conclusion

The obtained results suggest that this is a “switchable” theranostic nanocapsule with potential application as an ideal delivery system for simultaneous cancer diagnosis and therapy.

Interaction of Native Cyclodextrins and Their Hydroxypropylated Derivatives with Carbamazepine in Aqueous Solution. Evaluation of Inclusion Complexes and Aggregates Formation

A detailed comprehensive study on how the formation of soluble and insoluble carbamazepine/cyclodextrins (CBZ/CD) complexes (with consequent changes in the solid-phase composition) depends on the CD structure is not yet available. Moreover, the study of possible influence of this drug on the tendency of CDs and their complexes to self-aggregate is still lacking. Phase-solubility studies demonstrated that CDs and CBZ form a range of soluble (A_L-type: αCD, βCD, and hydroxypropylated CDs) and insoluble (B_S-type: γCD) complexes depending on CD used. HPβCD proved to be the best CD solubilizer for CBZ forming the most stable complex with highest apparent solubility, whereas γCD was shown to be the best native CD. For the native CDs, CBZ solubilization increases with increasing CD cavity diameter (αCD ≪ βCD < γCD). Solid phases collected from phase-solubility studies were characterized by Fourier-transformed infrared spectroscopy, differential scanning calorimetry, and X-ray powder diffraction to elucidate their composition and crystalline structure. They provided similar conclusions being overall supportive of phase-solubility, osmolality, and permeation studies results. Solid CBZ was the only detected component for A_L-type profiles over the CD concentration range studied, whereas precipitation of poorly soluble CBZ/γCD complexes (B_S-type) was observed (i.e., at and beyond plateau region). Osmometry and permeation studies were applied to evaluate the effect of CBZ on the aggregate formation and also to elucidate their influence on CD complex solubility and permeation profile. Permeation method was shown to be the most effective method to detect and evaluate aggregate formation in aqueous γCD and HPβCD solutions containing CBZ. CBZ did not affect the HPβCD tendency to self-aggregate but CBZ did modify the aggregation behavior of γCD decreasing the apparent critical aggregation concentration value from 4.2% (w/v) (in pure aqueous γCD solution) to 2.5% (w/v) (when CBZ was present).

The validity of nasal endoscopy in patients with chronic rhinosinusitis-An inter-rater agreement study

OBJECTIVES

Nasal endoscopy is a cornerstone in diagnosing sinonasal disease, but different raters might generate different results using the technique. Our study aims to evaluate the agreement between multiple raters to assess the validity of nasal endoscopy.

DESIGN/PARTICIPANTS

Three independent and blinded raters evaluated 28 patients (56 nasal cavities) diagnosed with chronic rhinosinusitis according to the European Position Paper on Rhinosinusitis and Nasal Polyps. The ratings were compared using unweighted Fleiss' kappa coefficients (K_f ) for each objective parameter.

SETTING

The department of Otorhinolaryngology, Odense University Hospital, Denmark.

MAIN OUTCOME MEASURES

The ratings were quantified in a modified Lund-Kennedy endoscopy score and focused on the objective parameters specified in the diagnostic criteria: polyps, oedema and discharge.

RESULTS

The raters agreed on the findings concerning polyps and discharge but not regarding oedema with the inter-rater agreement for the different parameters being: polyps K_f =.66 (SE .07, P<.001), oedema K_f =.05 (SE .07, P=.21), discharge K_f =.35 (SE .08, P<.001), oedema exclusively in middle meatus K_f =-.07 (SE .04, P=.8) and discharge exclusively in middle meatus K_f =.16 (SE .07, P=.01).

CONCLUSION

Using nasal endoscopy, the evaluation of polyps by multiple raters showed sufficient reliability indicating an acceptable objective evaluation. The evaluation of discharge achieved a fair level of agreement while the assessment of oedema could not achieve a sufficient reliability questioning the inclusion of oedema in the criteria for diagnosing sinonasal disease.

Formation of nanoparticles by cooperative inclusion between (S)-camptothecin-modified dextrans and β-cyclodextrin polymers

Novel (S)-camptothecin–dextran polymers were obtained by “click” grafting of azide-modified (S)-camptothecin and alkyne-modified dextrans. Two series based on 10 kDa and 70 kDa dextrans were prepared with a degree of substitution of (S)-camptothecin between 3.1 and 10.2%. The binding properties with β-cyclodextrin and β-cyclodextrin polymers were measured by isothermal titration calorimetry and fluorescence spectroscopy, showing no binding with β-cyclodextrin but high binding with β-cyclodextrin polymers. In aqueous solution nanoparticles were formed from association between the (S)-camptothecin–dextran polymers and the β-cyclodextrin polymers.

Primary and secondary restorative proctocolectomy for familial adenomatous polyposis: complications and long-term bowel function

AIM

The aim of the study was to evaluate intra-operative difficulties, complications and long-term bowel function in polyposis patients undergoing conversion of an ileorectal anastomosis to an ileoanal pouch, compared with patients with a primary ileoanal pouch operation.

METHOD

A national register-based retrospective study was performed with clinical follow-up and a questionnaire on long-term bowel function.

RESULTS

There were 84 patients in the study: 59 (70%) had a primary pouch operation and in 25 (30%) a secondary pouch procedure was attempted. This was abandoned, in one case, leaving 24 patients who had a successful secondary restorative proctocolectomy. The median (range) follow-up was 123 (0-359) months. There were no intra-operative difficulties in the 59 primary operations, but intra-operative difficulties were reported in nine of 25 secondary operations (P < 0.001). Complications within 1 month of surgery occurred in six of 59 primary operations and in none of 24 secondary operations (P < 0.001); and late surgical complications occurred in eight of 55 primary operations and in eight of 24 secondary operations (P = 0.13). The only difference in bowel function was a lower frequency of nocturnal defaecation after secondary pouch formation (P = 0.02).

CONCLUSION

Reoperation with proctectomy after a previous ileorectal anastomosis and conversion to restorative proctocolectomy is feasible in polyposis patients, with morbidity and functional results similar to those seen after a primary pouch operation.

Synthesis of β-cyclodextrin diazonium salts and electrochemical immobilization onto glassy carbon and gold surfaces

This study shows that diazotized β-cyclodextrin (β-CD) can be produced, isolated, and immobilized onto glassy carbon and gold surfaces. 4-(1,2,3-Triazol-4-yl)benzenediazonium-β-CD tetrafluoroborate (pDz-β-CD) and 3-(1,2,3-triazol-4-yl)benzenediazonium-β-CD tetrafluoroborate (mDz-β-CD) were successfully prepared by Cu((I))-catalyzed azide alkyne coupling (CuAAC) of 6-monodeoxy-6-monoazido-β-cyclodextrin (N(3)-β-CD) and 4-ethynylaniline and 3-ethynylaniline, respectively, followed by diazotization. The products were isolated and stored successfully for several months at -18 °C. The intermediates and products were verified by Attenuated Total Reflectance Fourier Transform Infrared, Nuclear Magnetic Resonance, and Heteronuclear Single Quantum Coherence. pDz-β-CD and mDz-β-CD were immobilized onto glassy carbon and gold surfaces facilitated by electrochemical reduction of the diazonium group. The thus generated aryl radical reacted with the surface. The modified gold surfaces were investigated by Polarization Modulation Infrared Reflection Absorption Spectroscopy and cyclic voltammetry employing the redox probe K(3)Fe(CN)(6) to analyze the extent of blocking of the surfaces. Finally, the availability of the cavity of surface-immobilized β-CD was shown by complexation of ferrocene followed by cyclic voltametric analysis.

Structural and spectroscopic features of lutein/butanoyl-β-cyclodextrin nanoassemblies

Lutein, the primary carotenoid present in the central area of the retina of eye appears to be associated with the protection against age-related macular degeneration (the leading cause of blindness in older adults). Its lipophilicity and consequently its scarce water solubility (1.3×10(-9)M) represent a drawback for bioavailability. To circumvent these unfavorable characteristics, in this work lutein (Lut) have been encapsulated in amphiphilic cyclodextrin (ACyD) by following the well-established strategy of entrapping a lipophilic drug in CyD carriers. Primary face butyrate modified β-cyclodextrins (C(4:7)) form in water nanoaggregates with a average size of 250nm and a ζ-potential of about -6mV. They are able to entrap lutein at 1:6 Lut/ACyD molar ratio by yielding nanoassemblies of vesicular aspect (320nm and -8mV) such as observed by static, dynamic and electrophoretic light-scattering. UV-vis measurements revealed that electronic properties of lutein were maintained when interact with ACyD nanoaggregates. The monitoring of the entapped carotenoid leaking from ACyD nanostructures was investigated suggesting the potential of Lut/ACyD nanoassemblies in drug delivery.

Size-controlled nanoassemblies based on cyclodextrin-modified dextrans

Nanoassemblies formed by host/guest interactions between two polymers in aqueous media are studied. Two types of polymers with the same dextran backbone are modified with adamantyl or βCD groups. The sizes of the spontaneously formed nanoassemblies depend on the βCD:Ada ratio and on the total concentration and composition of the mixtures. The results can be rationalized by assuming a core/shell structure of the nanoassemblies, the core resulting from associative phase separation of the two polymers and being stabilized by an external shell made of Ada-grafted dextran and containing ions adsorbed from the solution. Hydrophobic compounds such as benzophenone can be incorporated efficiently without inducing changes in properties of the nanoassemblies.

Methylated β-cyclodextrins: influence of degree and pattern of substitution on the thermodynamics of complexation with tauro- and glyco-conjugated bile salts

The complexation of 6 bile salts with various methylated β-cyclodextrins was studied to elucidate how the degree and pattern of substitution affects the binding. The structures of the CDs were determined by mass spectrometry and NMR techniques, and the structures of the inclusion complexes were characterized from the complexation-induced shifts of (13)C nuclei as well as by 2D ROESY NMR. Thermodynamic data were generated using isothermal titration calorimetry. The structure-properties analysis showed that methylation at O3 hinders complexation by partially blocking the cavity entrance, while methyl groups at O2 promote complexation by extending the hydrophobic cavity. Like in the case of 2-hydroxypropylated cyclodextrins, the methyl substituents cause an increased release of ordered water from the hydration shell of the bile salts, resulting in a strong increase in both the enthalpy and the entropy of complexation with increased number of methyl substituents. Due to enthalpy-entropy compensation the effect on the stability constant is relatively limited. However, when all hydroxyl groups are methylated, the rigid structure of the free cyclodextrin is lost and the complexes are severely destabilized due to very unfavorable entropies.

Hydroxypropyl-substituted β-cyclodextrins: influence of degree of substitution on the thermodynamics of complexation with tauroconjugated and glycoconjugated bile salts

The effect of the degree of substitution (DS) on the ability of hydroxypropylated β-cyclodextrin (HPβCD) to form inclusion complexes with six different bile salts, found within the intestinal tracts of rats, dogs, and humans, was studied by isothermal titration calorimetry. The composition and molecular structure of the cyclodextrin samples were characterized by MALDI-TOF mass spectrometry together with 1D and 2D-NMR, and some of the complexes were studied by 2D ROESY NMR. The stability and structure of the complexes were mainly determined by the position of hydroxyl groups on the bile salts and depended relatively little on the number of hydroxypropyl side chains on the CDs. The enthalpy and entropy of complexation exhibited a strong linear increase as the DS increased from 0 to 1, and a pronounced enthalpy-entropy compensation was observed. These observations are interpreted as an increased release of ordered water from the hydration shells of the bile salts, caused by the hydroxypropyl substituents on the rim of the CD. It is estimated that each CD hydroxypropyl substituent dehydrates a hydrophobic surface area of approximately 10 Å(2).

Cyclodextrin modified hydrogels of PVP/PEG for sustained drug release

Hydrogels are water swollen networks of polymers and especially hydrogels consisting of poly vinylpyrrolidone/poly ethyleneglycol-dimethacrylate (PVP/PEG-DMA) blends show promising wound care properties. Enhanced functionality of the hydrogels can be achieved by incorporating drugs and other substances that may assist wound healing into the gel matrix. Controlling the release of active compounds from the hydrogels may be possible by carefully modifying the polymer matrix. For this purpose, cyclodextrins (CD) were grafted to the polymer matrix in 4-5 w/w% in an attempt to retard the release of water-soluble drugs. Ibuprofenate (IBU) was chosen as model drug and loaded in IBU/CD ratios of 0.6, 1.2, and 2.5. Vinyl derivatives of alpha-, beta- and gamma-CD were produced, added to the prepolymer blend and cured by UV-light. During this curing process the CD derivatives were covalently incorporated into the hydrogel matrix. The modified hydrogels were loaded with ibuprofenate by swelling. The release of the model drug from CD modified hydrogels show that especially covalently bonded beta-cyclodextrin can change both the release rate and the release profile of ibuprofen.

The stability and dissolution properties of solid glucagon/gamma-cyclodextrin powder

In the present study, the solid-state stability and the dissolution of glucagon/gamma-cyclodextrin and glucagon/lactose powders were evaluated. Freeze-dried powders were stored at an increased temperature and/or humidity for up to 39 weeks. Pre-weighed samples were withdrawn at pre-determined intervals and analyzed with HPLC-UV (HPLC=high performance liquid chromatography, UV=ultraviolet), HPLC-ESI-MS (ESI-MS=electrospray ionization mass spectrometry), SEC (size-exclusion chromatography), turbidity measurements and solid-state FTIR (Fourier Transform Infrared Spectroscopy). Dissolution of glucagon was evaluated at pH 2.5, 5.0 and 7.0. In addition, before storage, proton rotating-frame relaxation experiments of solid glucagon/gamma-cyclodextrin powder were conducted with CPMAS ((13)C cross-polarization magic-angle spinning) NMR (nuclear magnetic resonance) spectroscopy. In the solid state, glucagon was degraded via oxidation and aggregation and in the presence of lactose via the Maillard reaction. The solid-state stability of glucagon/gamma-cyclodextrin powder was better than that of glucagon/lactose powder. In addition, gamma-cyclodextrin improved the dissolution of glucagon at pH 5.0 and 7.0 and delayed the aggregation of glucagon after its dissolution at pH 2.5, 5.0 and 7.0. There was no marked difference between the proton rotating-frame relaxation times of pure glucagon and gamma-cyclodextrin, and thus, the presence of inclusion complexes in the solid state could not be ascertained by CPMAS NMR. In conclusion, when compared to glucagon/lactose powder, glucagon/gamma-cyclodextrin powder exhibited better solid-state stability and more favorable dissolution properties.

The effect of cyclodextrins on chemical and physical stability of glucagon and characterization of glucagon/gamma-CD inclusion complexes

The purpose of the study was to evaluate the effect of cyclodextrin (CD) complexation on the chemical and physical stability of a polypeptide hormone glucagon and to study the interactions between glucagon and gamma-cyclodextrin molecules in inclusion complexes. The chemical stability of glucagon at pH 2.0 was studied with HPLC-UV and HPLC-MS/MS. The physical stability of glucagon at pH 2.5 was studied by measuring the turbidity (A(405 nm)) and viscosity (Ostwald capillary viscosimeter) of the samples. The structure of glucagon/gamma-CD complexes at pH 2.5 was studied with 2D-NMR. The presence of various CDs increased the chemical half-life of glucagon at pH 2.0 (37 degrees C, 0.01 M HCl, ionic strength 0.15) and prolonged the lag-time before aggregation at pH 2.5 (0.9% (w/v) NaCl in 3.2 mM HCl). The NMR studies showed that the side chains of all the aromatic amino acid residues (Phe6, Tyr10, Tyr13, Phe22, Trp25) and leucines (Leu14 and Leu26) of glucagon interacted with the cavities of the gamma-CD molecules. The present study shows that glucagon forms inclusion complexes with cyclodextrins in acidic solution, resulting in an improvement in its chemical and physical stability.

Cyclodextrin controlled release of poorly water-soluble drugs from hydrogels

The effect of 2-hydroxypropyl-beta-cyclodextrin and gamma-cyclodextrin on the release of ibuprofen, ketoprofen and prednisolone was studied. Stability constants calculated for inclusion complexes show size dependence for complexes with both cyclodextrins. Hydrogels were prepared by ultraviolet irradiation and release of each model drug was studied. For drugs formulated using cyclodextrins an increase in the achievable concentration and in the release from hydrogels was obtained due to increased solubility, although the solubility of all gamma-cyclodextrin complexes was limited. The load also was increased by adjusting pH for the acidic drugs and this exceeds the increase obtained with gamma-cyclodextrin addition.

Structural background of cyclodextrin-protein interactions

Cyclodextrins are cyclic oligosaccharides with the shape of a hollow truncated cone. Their exterior is hydrophilic and their cavity is hydrophobic, which gives cyclodextrins the ability to accommodate hydrophobic molecules/moieties in the cavity. This special molecular arrangement accounts for the variety of beneficial effects cyclodextrins have on proteins, which is widely used in pharmacological applications. We have studied the interaction between beta-cyclodextrin and four non-carbohydrate-binding model proteins: ubiquitin, chymotrypsin inhibitor 2 (CI2), S6 and insulin SerB9Asp by NMR spectroscopy at varying structural detail. We demonstrate that the interaction of beta-cyclodextrin and our model proteins takes place at specific sites on the protein surface, and that solvent accessibility of those sites is a necessary but not compelling condition for the occurrence of an interaction. If this behaviour can be generalized, it might explain the wide range of different effects of cyclodextrins on different proteins: aggregation suppression (if residues responsible for aggregation are highly solvent accessible), protection against degradation (if point of attack of a protease is sterically 'masked' by cyclodextrin), alteration of function (if residues involved in function are 'masked' by cyclodextrin). The exact effect of cyclodextrins on a given protein will always be related to the particular structure of this protein.

Structural basis for cyclodextrins' suppression of human growth hormone aggregation

Many therapeutic proteins require storage at room temperature for extended periods of time. This can lead to aggregation and loss of function. Cyclodextrins (CDs) have been shown to function as aggregation suppressors for a wide range of proteins. Their potency is often ascribed to their affinity for aromatic amino acids, whose surface exposure would otherwise lead to protein association. However, no detailed structural studies are available. Here we investigate the interactions between human growth hormone (hGH) and different CDs at low pH. Although hGH aggregates readily at pH 2.5 in 1 M NaCl to form amorphous aggregates, the presence of 25 to 50 mM of various beta-CD derivatives is sufficient to completely avoid this. alpha- and gamma-CD are considerably less effective. Stopped-flow data on the aggregation reaction in the presence of beta-CD are analyzed according to a minimalist association model to yield an apparent hGH-beta-CD dissociation constant of approximately 6 mM. This value is very similar to that obtained by simple fluorescence-based titration of hGH with beta-CD. Nuclear magnetic resonance studies indicate that beta-CD leads to a more unfolded conformation of hGH at low pH and predominantly binds to the aromatic side-chains. This indicates that aromatic amino acids are important components of regions of residual structure that may form nuclei for aggregation.

Two-step enzymatic synthesis of maltooligosaccharide esters

Glucose and maltose esters were synthesised in organic media by employing a lipase (E.C. 3.1.1.3) from Candida antarctica. In a second reaction step, a transglycosylation catalysed by a cyclodextrin glycosyltransferase (E.C. 2.4.1.19) from either Paenibacillus sp. F8 or Bacillus sp. strain no. 169 (DSM 2518) extended the degree of polymerisation (DP) of the carbohydrate moieties of the carbohydrate esters. The donor substrates used were either a cyclodextrin, a maltooligosaccharide or starch. The highest rate of low DP maltooligosaccharide ester formation was obtained when starch was used as glycosyl donor and caproyl maltose as glycosyl acceptor. The structures of two of the products were identified by 1H and 13C NMR and MALDI-TOF MS as capronate monoesters of maltotriose and maltotetraose, with the ester bond at C-6 of the second glucose unit from the reducing end.

Suitability and limitations of methods for characterisation of activity of malto-oligosaccharide-forming amylases

The suitability and limitations of essential methods and reference substrates used for characterisation of activity of amylolytic enzymes is investigated. Saccharogenic, chromogenic and chromatographic methods are included. The results are discussed in relation to the measurement of reaction rates, determination of action mode and product specificity and the impact on identification and nomenclature of malto-oligosaccharide-forming amylases. An accurate determination of reaction rates using the saccharogenic methods strongly depends on the degree of polymerisation (DP) of the standards used and the hydrolysis products formed by the amylase. Particularly the use of glucose as standard can lead to overestimates due to the differences in the reducing potential of glucose and malto-oligosaccharides. The reliability of the chromogenic methods for determination of action mode depends on the DP of the substrate and the specificity of the amylase. For a characterisation of the starch hydrolysis products and the variation in the DP during hydrolysis, high performance anion-exchange chromatography with pulsed amperometric detection provided a fast and reliable method. A literature survey revealed varying and inconsistent use of nomenclature of malto-oligosaccharide forming amylases. Therefore a systematic approach identifying three main classes of activity is suggested using not only the mode of action and the DP of the major product but also the stage of hydrolysis at which this product is formed.

Azathioprine and 6-mercaptopurine for the treatment of perianal Crohn's disease in children

Numerous adult studies show a 30-65% response rate to azathioprine (AZA) or 6-mercaptopurine (6-MP) for significant perianal Crohn's disease. The aim of this study was to evaluate whether these drugs healed pediatric perianal Crohn's disease. Records of pediatric Crohn's patients were retrospectively reviewed for significant perianal disease treated with AZA or 6-MP for > or =6 months. The patient's perianal disease was reviewed and evaluated for fistulas, drainage, induration, and tenderness. In addition, the patients were given a score using the Irvine Perianal Disease Activity Index (PDAI). Patients were retrospectively scored upon initiation of treatment and after six months of therapy. Possible scores ranged from 0-20. Twenty patients met the study criteria. Five patients were considered treatment failures. One patient required a colostomy after 1.5 months of therapy, one developed pancreatitis, and three were noncompliant with therapy. Of the remaining 15 patients who were treated for > or =6 months, 67% had an improvement in drainage, 73% in tenderness, 60% in induration, and 40% in fistula closure. The mean Irvine PDAI was 7.67 +/- 2.19 initially and 4.40 +/- 1.72 after six months of therapy. The improvement was statistically significant (p < 0.001). AZA and 6-MP are effective treatments for healing significant perianal Crohn's disease in pediatrics.

Rapid detection of malto-oligosaccharide-forming bacterial amylases by high performance anion-exchange chromatography

High performance anion-exchange chromatography with pulsed amperometric detection was applied for the rapid analysis of malto-oligosaccharides formed by extracellular enzyme preparations from 49 starch-degrading bacterial strains isolated from soil and compost samples. Malto-oligosaccharide-forming amylases, indicated by a predominant formation of maltohexaose from starch, were produced by enzyme preparations from four of the isolates growing at pH 7.0 and 10.

Production of cyclomaltononaose (delta-cyclodextrin) by cyclodextrin glycosyltransferases from Bacillus spp. and bacterial isolates

The conversion of soluble starch to cyclomaltohexaose (alpha-CD), cyclomaltoheptaose (beta-CD), cyclomaltooctaose (gamma-CD) and cyclomaltononaose (delta-CD) by cyclodextrin glycosyltransferases (E.C. 2.4.1.19) from Bacillus spp. and bacterial isolates was studied. The results show that delta-CD was formed by all the enzymes investigated in the range of 5%-11.5% of the total amount of alpha-, beta-, gamma-, and delta-CD produced.

Immuno-capillary electrophoresis for the characterization of a monoclonal antibody against DNA

A monoclonal antibody against DNA established from a mouse strain that spontaneously develops systemic lupus erythematosus was characterized by migration shift immuno-capillary electrophoresis. The minimal size for DNA binding antibody was > 16 bases and the interaction with a double-stranded 32-mer oligonucleotide was almost one order of magnitude stronger than the interaction with a single-stranded oligonucleotide. The binding was highly dependent on the ionic strength conditions with an increase in binding with a decrease in ionic strength. The estimate of the dissociation constant for the antibody binding of a single stranded 32-mer oligonucleotide was 0.62 microM at pH 7.90. This value was in good agreement with the value of 0.44 microM measured by an independent method using biosensor (surface plasmon resonance) technology.

Effects of illumination intensity on bacteriochlorophyllc homolog distribution inChloroflexus aurantiacus grown under controlled conditions

Green photosynthetic bacteria contain a mixture of stereoisomers and homologs of their major light harvesting pigment, bacteriochlorophyll (BChl)c. We have determined the distribution of photosynthetic pigments in the green filamentous bacteriumChloroflexus aurantiacus grown in turbidostat culture under light-limited conditions at 5 different illumination intensities. Pigments were extracted from isolated cells, analyzed by HPLC, and the homologs of BChlc identified by their mass spectra. The ratio between BChlc, BChla and carotenoid remained constant at low illumination intensities; at higher intensities BChla and carotenoid increased in parallel compared to BChlc. The BChlc homolog distribution changed even under conditions where the ratio of the total amount to the other pigments was unchanged, but there were no evidence for a constant stoichiometric ratio between any pair of homologs.

Responses and molecular heterogeneity of IR-GIP after intraduodenal glucose and fat

The plasma responses and molecular heterogeneity of human immunoreactive gastric inhibitory polypeptide (IR-GIP) after intraduodenal administration of equicaloric amounts of glucose (25 g) and fat (10 g) were determined with five different antisera. Two of these do not cross-react with 8 kdaltons (kDa) IR-GIP. In the fasting state plasma IR-GIP concentrations were highest measured with antisera, which detected both 5 and 8 kDa IR-GIP. The total integrated or incremental IR-GIP areas were similar after glucose and fat when determined with the same antiserum. When antisera with similar cross-reactivity with human 5 kDa IR-GIP were compared, no difference in incremental IR-GIP areas after either stimulus was found between antisera that did and did not measure 8 kDa IR-GIP. Gel filtration of plasma showed a consistent increase in 5 kDa IR-GIP 60 min after both glucose and fat but small and inconsistent changes in 8 kDa IR-GIP. Thus fat on a weight and molar basis is more potent than glucose in releasing IR-GIP. Both fat and glucose release predominantly the 5 kDa IR-GIP. Although of importance for the absolute IR-GIP level in plasma, 8 kDa IR-GIP contributes little to the increase in IR-GIP after both stimuli.