Optimization of Ultrasound-Assisted Pretreatment for Accelerating Rehydration of Adzuki Bean (Vigna angularis)

Adzuki bean (Vigna angularis), which provides plant-based proteins and functional substances, requires a long soaking time during processing, which limits its usefulness to industries and consumers. To improve this, ultrasonic treatment using high pressure and shear force was judged to be an appropriate pretreatment method. This study aimed to determine the optimal conditions of ultrasound treatment for the improved hydration of adzuki beans using the response surface methodology (RSM). Independent variables chosen to regulate the hydration process of the adzuki beans were the soaking time (2-14 h, X1), treatment intensity (150-750 W, X2), and treatment time (1- 10 min, X3). Dependent variables chosen to assess the differences in the beans post-immersion were moisture content, water activity, and hardness. The optimal conditions for treatment deduced through RSM were a soaking time of 12.9 h, treatment intensity of 600 W, and treatment time of 8.65 min. In this optimal condition, the values predicted for the dependent variables were a moisture content of 58.32%, water activity of 0.9979 aw, and hardness of 14.63 N. Upon experimentation, the results obtained were a moisture content of 58.28 ± 0.56%, water activity of 0.9885 ± 0.0040 aw, and hardness of 13.01 ± 2.82 g, confirming results similar to the predicted values. Proper ultrasound treatment caused cracks in the hilum, which greatly affects the water absorption of adzuki beans, accelerating the rate of hydration. These results are expected to help determine economically efficient processing conditions for specific purposes, in addition to solving industrial problems associated with the low hydration rate of adzuki beans.

Retrograded octenylsuccinylated maize starch-based emulgels for a promising oral delivery system of curcumin

Emulgels are a type of soft solid delivery system that exploit the merits of both emulsions and gels, namely, bioactive encapsulability and structural stability, respectively. We utilized retrograded/octenylsuccinylated maize starch (ROMS) to fabricate the curcumin-loaded emulgel. Emulgels (oil volume fraction, 0.20) prepared with 1-4 % w/w ROMS exhibited fluid-like behaviors while emulgels with 5-8 % w/w ROMS exhibited a gel-like consistency. Compared to a fluidic emulsion stabilized with 3 % w/w octenylsuccinylated maize starch, the emulgels showed more sustained lipolysis and controlled curcumin release patterns. These results were attributed to rigid ROMS structures at the outer layer of oil droplets, hindering the lipase approach onto the oil/water interface and curcumin diffusion from the interface. Additionally, the bioaccessibility of curcumin in ROMS-stabilized emulgels was enhanced >9.6-fold compared to that of a curcumin solution. Furthermore, emulgels prepared with 8 % w/w ROMS exhibited a high yield stress (376.4 Pa) and maintained appearance and droplet size for 60 days of storage at 4 °C. Consequently, this emulgel has potential as a lipophilic bioactive-containing soft gel with sustained digestion and controlled release properties. Our findings may provide insights into rational delivery system designs.

Comparison of the pretreatment methods for enhancing hydration of water-soaked adzuki beans (Vigna angularis)

Five pretreatments methods, cold plasma, pressure drop, heating, and bath-type and probe-type sonications were compared to shorten the rehydration process of adzuki bean (Vigna angularis) soaked before the cooking in terms of the hydration and softening efficacies. Moisture content and water activity of the probe-type sonicated beans were most dramatically increased as 11-45% and 0.59-0.97 after soaking for only 2 h, respectively (non-treated: 11-12% and 0.59-0.66). Accordingly, the probe-type sonicated beans were most rapidly softened as 27-5 N in the 2 h-soaking and exhibited the lowest hardness after soaking/cooking as ~ 0.97 N (non-treated: 27-21 N and ~ 5.5 N, respectively). According to scanning electron micrographs, these results can be attributed to formation of prominent fissures or scars in the hilum of the probe-type sonicated beans. Consequently, this study will be provide valuable information for developing a rational process in food industry to shorten the rehydration of the adzuki beans.

Enhancing stability and bioavailability of sulforaphene in radish seed extracts using nanoemulsion made with high oleic sunflower oil

The effect of nanoemulsions on the stability and bioavailability of sulforaphene (SFEN) in radish seed extract (RSE) was investigated. Four types of oil were used as lipid ingredients of the nanoemulsions: soybean, high oleic acid sunflower, coconut, and hydrogenated palm oils. SFEN in RSE nanoemulsions showed greater stability to temperature, acid, and alkaline conditions than SFEN in RSE suspended in water (RSE-S). Particularly under alkaline conditions, the half-life of SFEN in the nanoemulsion with high oleic sunflower oil (RSE-HOSO) was 8 times longer than that of RSE-S. Furthermore, in the pharmacokinetics study, it was observed that AUC0-8 increased and oral clearance (CL/F) decreased significantly in rats orally administered RSE-HOSO compared with RSE-S (p < 0.05). This study indicates that the type of oil used in nanoemulsions affects the stability and bioavailability of SFEN in RSE. These results may provide a guideline for the development of functional foods containing RSE.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01304-2.

Synthesis and physicochemical characterization of acyl myricetins as potential anti-neuroexocytotic agents

Acyl myricetins (monopropionyl-, dipropionyl-, and monooctanoyl-myricetin, termed as MP₁, MP₂, and MO₁, respectively) were synthesized through enzymatic or non-enzymatic esterification reaction of myricetin aglycone. Structure study indicated the hydroxyl group at C4' in B-ring was highly susceptible to acylation. Over its parental myricetin, acylated compounds showed enhanced lipophilicity (from 7.4- to 26.3-fold) and oxidative stability (from 1.9- to 3.1-fold) on the basis of logP and decay rate, respectively. MO₁, presenting the physicochemical superiority compared to the others, provided lowest EC₅₀ value of 2.51 μM on inhibition of neutrotransmitter release and CC₅₀ value of 59.0 μM, leading to widest therapeutic window. All myricetin esters did not show any irritation toxicity when assessed with a chicken embryo assay. This study describes information on acylation of myricetin that has not yet been explored, and suggests that MO₁ has membrane fusion-arresting and anti-neuroexocytotic potential for industrial application due to its enhanced biological properties.

Delayed Quality Deterioration of Low-Moisture Cereal-Based Snack by Storing in an Active Filler-Embedded LDPE Zipper Bag

This study focused on controlling the vapor permeability of an active zipper bag and preserving the quality of cereal-based snacks during the storage period at home. The active zipper bag was prepared by extruding low-density polyethylene with active fillers obtained from natural mineral materials. The active zipper bag showed the same transparent appearance as the existing one but showed 21% lower water vapor capability. As a result, during a 20-day storage period, three types of grain-based snacks (biscuits, shortbread cookies, and puffed snacks) showed delayed increases in weight, moisture content, and moisture activity when stored in an active zipper bag. In addition, this also affected the texture of the biscuits and shortbread cookies, in which the area under the curve was reduced significantly after appearing at a peak during the hardness measurement. On the other hand, the decrease in the number of air cell fracture events in puffed snacks was remarkable. This result suggests that the inner microstructure is preserved better when stored in an active zipper bag. In conclusion, the active zipper bag showed poor water vapor permeability, suggesting that the prepared zipper bag can be developed as snack packaging.

Neuron-recognizable characteristics of peptides recombined using a neuronal binding domain of botulinum neurotoxin

Recombinant peptides were designed using the C-terminal domain (receptor binding domain, RBD) and its subdomain (peptide A2) of a heavy chain of botulinum neurotoxin A-type 1 (BoNT/A1), which can bind to the luminal domain of synaptic vesicle glycoprotein 2C (SV2C-LD). Peptide A2- or RBD-containing recombinant peptides linked to an enhanced green fluorescence protein (EGFP) were prepared by expression in Escherichia coli. A pull-down assay using SV2C-LD-covered resins showed that the recombinant peptides for CDC297 BoNT/A1, referred to EGFP-A2' and EGFP-RBD', exhibited ≥ 2.0-times stronger binding affinity to SV2C-LD than those for the wild-type BoNT/A1. Using bio-layer interferometry, an equilibrium dissociation rate constant (K_D) of EGFP-RBD' to SV2C-LD was determined to be 5.45 μM, which is 33.87- and 15.67-times smaller than the K_D values for EGFP and EGFP-A2', respectively. Based on confocal laser fluorescence micrometric analysis, the adsorption/absorption of EGFP-RBD' to/in differentiated PC-12 cells was 2.49- and 1.29-times faster than those of EGFP and EGFP-A2', respectively. Consequently, the recombinant peptides acquired reasonable neuron-specific binding/internalizing ability through the recruitment of RBD'. In conclusion, RBDs of BoNTs are versatile protein domains that can be used to mark neural systems and treat a range of disorders in neural systems.

Development of End-Spliced Dimeric Nanodiscs for the Improved Virucidal Activity of a Nanoperforator

Lipid-bilayer nanodiscs (NDs) wrapped in membrane scaffold proteins (MSPs) have primarily been used to study membrane proteins of interest in a physiological environment. Recently, NDs have been employed in broader applications including drug delivery, cancer immunotherapy, bio-imaging, and therapeutic virucides. Here, we developed a method to synthesize a dimeric nanodisc, whose MSPs are circularly end-spliced, with long-term thermal stability and resistance to aggregation. The end-spliced nanodiscs (esNDs) were assembled using MSPs that were self-circularized inside the cytoplasm ofEscherichia colivia highly efficient protein trans-splicing. The esNDs demonstrated a consistent size and 4-5-fold higher stability against heat and aggregation than conventional NDs. Moreover, cysteine residues on trans-spliced circularized MSPs allowed us to modulate the formation of either monomeric nanodiscs (essNDs) or dimeric nanodiscs (esdNDs) by controlling the oxidation/reduction conditions and lipid-to-protein ratios. When the esdNDs were used to prepare an antiviral nanoperforator that induced the disruption of the viral membrane upon contact, antiviral activity was dramatically increased, suggesting that the dimerization of nanodiscs led to cooperativity between linked nanodiscs. We expect that controllable structures, long-term stability, and aggregation resistance of esNDs will aid the development of novel versatile membrane-mimetic nanomaterials with flexible designs and improved therapeutic efficacy.

Objective Quantitation of Focal Sweating Areas Using a Mouse Sweat-assay Model

In vivo sweat quantitation assays are required for the development of drugs for the management of focal hyperhidrosis before clinical trials; however, in vivo assays, particularly mouse models, are rare. Even in sweat assays using mice, sweating is quantitated by manually counting the number of sweating spots, which can contribute to various errors owing to arbitrary judgment. In this study, we developed a mouse sweat-assay model and a method for quantitating the amount of sweating to remove possible errors. The use of the iodine-starch test in the castor oil-covered hind footpad skin of anesthetized mice resulted in the sweating area being stained blue-black. After the anesthesia and treatment with drugs (pilocarpine, glycopyrrolate, botulinum neurotoxin, myricetin, and myricetin-loaded lipid nanoparticles), the remaining area of the footpad skin was eliminated from the acquired footpad images using ImageJ. Blue pixels extracted from the footpad image are automatically adjusted using the Phansalkar method, where the percentage of the blue area was determined based on the whole hind footpad skin area, finally indicating the percentage of the sweating area. Using this mouse model and analysis for sweat assays, a clear difference between the control group and antiperspirant-administered group was observed with respect to the sweating area % with no error. In conclusion, this assay can be used as a preclinical tool to screen potential antiperspirant drugs. Graphic abstract: Overview of the mouse-model sweat assay and objective quantitation of the focal sweating area.

Visible on-site detection of Ara h 1 by the switchable-linker-mediated precipitation of gold nanoparticles

Biosensors have been widely applied in tests for allergens, but on-site detection remains a challenge. Herein, we proposed a detection procedure for peanut Ara h 1 as a representative allergen, which was extracted from a cookie, thereby minimising the need for any complex pretreatment that was difficult to perform, and enabling the visual detection of the target without the use of analytical equipment. The extraction procedure was performed in less than 30 min using a syringe and filter (0.45 μm). The detection method for Ara h 1 was based on the aggregation of switchable linkers (SL) and gold nanoparticles (AuNP), and the presence of 0.19 mg peanut protein per 30 g of cookie could be confirmed within 30 min based on the AuNP/SL concentration ratio by the precipitation. This proposed procedure could be successfully applied to the detection of a wide range of food allergens.

Development of fluorescent Escherichia coli for a whole-cell sensor of 2'-fucosyllactose

2′-Fucosyllactose (2′-FL), a major component of fucosylated human milk oligosaccharides, is beneficial to human health in various ways like prebiotic effect, protection from pathogens, anti-inflammatory activity and reduction of the risk of neurodegeneration. Here, a whole-cell fluorescence biosensor for 2′-FL was developed. Escherichia coli (E. coli) was engineered to catalyse the cleavage of 2′-FL into l-fucose and lactose by constitutively expressing α-l-fucosidase. Escherichia coli ∆L YA, in which lacZ is deleted and lacY is retained, was employed to disable lactose consumption. E. coli ∆L YA constitutively co-expressing α-l-fucosidase and a red fluorescence protein (RFP) exhibited increased fluorescence intensity in media containing 2′-FL. However, the presence of 50 g/L lactose reduced the RFP intensity due to lactose-induced cytotoxicity. Preadaptation of bacterial strains to fucose alleviated growth hindrance by lactose and partially recovered the fluorescence intensity. The fluorescence intensity of the cell was linearly proportional to 1–5 g/L 2′-FL. The whole-cell sensor will be versatile in developing a 2′-FL detection system.

Dynamics and risk indicators of intrasinus elevation height following transalveolar sinus floor elevation with immediate implant placement: a longitudinal cohort study

Successful intrasinus graft consolidation is essential for the treatment outcome of transalveolar sinus floor elevation (SFE). This study was performed to examine the dynamics and risk indicators related to the elevation height after transalveolar SFE with grafting material and simultaneous implant placement. Fifty-two patients with 55 sites undergoing transalveolar SFE with immediate implant placement were enrolled retrospectively. Cone beam computed tomography (CBCT) images were collected and saved in DICOM format, at the following time-points: pre-surgery (T0), immediately post-surgery (T1), and 6 months post-surgery (T2). Voxel-based CBCT superimposition was performed to measure the sinus width, residual alveolar height, implant protrusion length, total elevation height, and apical graft height. The change in total elevation height from T1 to T2 was defined as the study outcome. Clinical and linear variables were analysed using linear regression. From T1 to T2, the total elevation height showed an average reduction of 1.0±1.1mm, while 10.9% sites showed an increased elevation height. Univariate regression analysis showed no significant correlation between tested clinical or linear variables and the study outcome. The results suggest that the change in elevation height was not influenced by the alveolar or sinus dimensions, graft materials, implant diameter, implant protrusion length, or the total elevation height at T1.

Characterization of Ginkgo biloba Leaf Flavonoids as Neuroexocytosis Regulators

Ginkgo biloba leaf (GBL) is known as a potential source of bioactive flavonoids, such as quercetin, arresting the neuronal soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-zippering. Here, the GBL flavonoids were isolated in two different manners and then examined for their bioactivity, physicochemical stability, and biocompatibility. The majority of flavonoids in the non-hydrolyzed and acidolyzed isolates, termed non-hydrolyzed isolate (NI) and acidolyzed isolate (AI) hereafter, were rich in flavonol glycosides and aglycones, respectively. Glycosidic/aglyconic quercetin and kaempferol were abundant in both NI and AI, whereas a little of apigenin, luteolin, and isorhamnetin were found in AI. NI was more thermostable in all pH ranges than quercetin, kaempferol, and AI. NI and AI both inhibited neurotransmitter release from differentiated neuronal PC-12 cells. NI and AI showed 1/2–1/3 lower EC₅₀/CC₅₀ values than quercetin and kaempferol. The NI and AI exhibited no toxicity assessed by the tests on chorioallantoic membranes of hen’s eggs, removing toxicological concerns of irritation potential. Moreover, GBL isolates, particularly AI, showed antioxidant and anti-inflammatory activities in the use below the CC₅₀ levels. Taken together, these results suggest that GBL isolates that are rich in antioxidant flavonoids are effective anti-neuroexocytotic agents with high stability and low toxicity.

Plasmid Display for Stabilization of Enzymes Inside the Cell to Improve Whole-Cell Biotransformation Efficiency

Recombinant whole-cell biocatalysts are widely used for biotransformation of valuable products. However, some key enzymes involved in biotransformation processes are unstable and cannot be easily expressed in the functional form. In this study, we describe a versatile platform for enzyme stabilization inside the cell: Intracellularly Immobilized Enzyme System (IIES). A 1,2-fucosyltransferase from Pedobactor saltans (PsFL) and a 1,3-fucosyltransferase from Helicobacter pylori (HpFL), chosen as model proteins, were fused with Oct-1 DNA-binding domain, which mediated the formation of a plasmid-protein complex. Oct-1 fusion enabled both soluble and stable expression of recombinant proteins in the cytoplasm because the fusion proteins were stabilized on the plasmid like immobilized enzymes bound to solid surface. As a result, Oct-1-fusion proteins exhibited significantly greater product titer and yield than non-fusion proteins. Use of fusion proteins PsFL-Oct-1 with C-terminal Oct-1 and Oct-1-PsFL with N-terminal Oct-1 resulted in ~3- and ~2-fold higher 2'-fucosyllactose titers, respectively, than with the use of PsFL alone. When Oct-1 was fused to HpFL, which requires dimerization through heptad repeats, almost two times more 3-fucosyllactose was produced. Fucosyllactose has been used as a food additive because it has various beneficial effects on human health. We anticipate that IIES using Oct-1 fusion protein developed in this study can be applied to stabilize other unstable enzymes.

Envelope-deforming antiviral peptide derived from influenza virus M2 protein

Molecules interfering with lipid bilayer function exhibit strong antiviral activity against a broad range of enveloped viruses, with a lower risk of resistance development than that for viral protein-targeting drugs. Amphipathic peptides are rich sources of such membrane-interacting antivirals. Here, we report that influenza viruses were effectively inactivated by M2 AH, an amphipathic peptide derived from the M2 protein of the influenza virus. Although overall hydrophobicity (<H>) of M2 AH was not related to antiviral activity, modification of the hydrophobic moment (<μH>) of M2 AH dramatically altered the antiviral activity of this peptide. M2 MH, a derivative of M2 AH with a <μH> of 0.874, showed a half maximal inhibitory concentration (IC₅₀) of 53.3 nM against the A/PR/8/34 strain (H1N1), which is 16-times lower than that of M2 AH. The selectivity index (IC₅₀/CC₅₀), where CC₅₀ is the half maximal cytotoxic concentration, was 360 for M2 MH and 81 for M2 AH. Dynamic light scattering spectroscopy and electron microscopy revealed that M2 AH-derived peptides did not disrupt liposomes but altered the shape of viruses. This result suggests that the shape of virus envelope was closely related to its activity. Thus, we propose that deforming without rupturing the membranes may achieve a high selectivity index for peptide antivirals.

Endocytosing Escherichia coli as a Whole-Cell Biocatalyst of Fatty Acids

Whole cell biocatalysts can be used to convert fatty acids into various value-added products. However, fatty acid transport across cellular membranes into the cytosol of microbial cells limits substrate availability and impairs membrane integrity, which in turn decreases cell viability and bioconversion activity. Because these problems are associated with the mechanism of fatty acid transport through membranes, a whole-cell biocatalyst that can form caveolae-like structures was generated to promote substrate endocytosis. Caveolin-1 ( CAV1) expression in Escherichia coli increased both the fatty acid transport rate and intracellular fatty acid concentrations via endocytosis of the supplemented substrate. Furthermore, fatty-acid endocytosis alleviated substrate cytotoxicity in E. coli. These traits attributed to bacterial endocytosis resulted in dramatically elevated biotransformation efficiencies in fed-batch and cell-recycle reaction systems when caveolae-forming E. coli was used for the bioconversion of ricinoleic acid (12-hydroxyoctadec-9-enoic acid) to ( Z)-11-(heptanoyloxy) undec-9-enoic acid. We propose that CAV1-mediated endocytosing E. coli represents a versatile tool for the biotransformation of hydrophobic substrates.

Inactivation of Bacillus cereus ATCC 14579 Spore on Garlic with Combination Treatments of Germinant Compounds and Superheated Steam

HIGHLIGHTS

Germinant compounds were combined with SHS to inactivate B. cereus spores. B. cereus spores were inactivated effectively by SHS after Ala+IMP treatment. Inactivation trend was analyzed by the Weibull model, and t₃ d values were determined. Sublethal injury was not observed by SHS after Ala+IMP treatment.

Virucidal nano-perforator of viral membrane trapping viral RNAs in the endosome

Membrane-disrupting agents that selectively target virus versus host membranes could potentially inhibit a broad-spectrum of enveloped viruses, but currently such antivirals are lacking. Here, we develop a nanodisc incorporated with a decoy virus receptor that inhibits virus infection. Mechanistically, nanodiscs carrying the viral receptor sialic acid bind to influenza virions and are co-endocytosed into host cells. At low pH in the endosome, the nanodiscs rupture the viral envelope, trapping viral RNAs inside the endolysosome for enzymatic decomposition. In contrast, liposomes containing a decoy receptor show weak antiviral activity due to the lack of membrane disruption. The nanodiscs inhibit influenza virus infection and reduce morbidity and mortality in a mouse model. Our results suggest a new class of antivirals applicable to other enveloped viruses that cause irreversible physical damage specifically to virus envelope by viruses' own fusion machine. In conclusion, the lipid nanostructure provides another dimension for antiviral activity of decoy molecules.

Short communication: Purple corn (Zea mays L.) stover silage with abundant anthocyanins transferring anthocyanin composition to the milk and increasing antioxidant status of lactating dairy goats

The present study used 16 multiparous lactating Saanen dairy goats (body weight, 41.80 ± 2.92 kg; mean ± standard deviation) with healthy and symmetrical udders. Goats were divided into 2 blocks of 8 goats based on milk yield averaged from 75 d in milk in a randomized completed block design. The 2 study groups were the control (CSSS), in which goats were fed sticky corn stover silage, and the treatment (TPSS), in which goats were fed anthocyanin-rich purple corn (Zea mays L.) stover silage (PSS). The results indicated that the TPSS group led to an elevation in the content of milk lactose relative to the CSSS. The inclusion of anthocyanin-rich PSS had no effect on the level of 5 particular anthocyanins [i.e., cyanidin-3-glucoside, delphinidin, cyanidin, pelargonidin (Pel), as well as total anthocyanins in milk]. The pelargonidin-3-glucoside and malvidin were unable to be detected in both groups. However, the TPSS resulted in higher levels of peonidin (Peo) and malvidin-3-O-glucoside (M3G) compared with the control. Moreover, goats receiving TPSS exhibited a higher level of superoxide dismutase (SOD) in plasma and milk relative to the CSSS. Interestingly, some positive correlations were detected between the certain milk components [i.e., fat and total solids as well as fat and solids-not-fat (SNF); protein and SNF; and total solids and SNF]. In addition, the positive correlations were observed between individual anthocyanins (cyanidin-3-glucoside, delphinidin, Peo, M3G, cyanidin, and Pel) and total anthocyanins. Specifically, stronger positive correlations were noted between several antioxidant enzymes and anthocyanin composition in milk (total antioxidant capacity and Pel; SOD and Peo as well as SOD and M3G). Taken together, PSS with abundant anthocyanins can transfer anthocyanins to the milk and enhance the amount of antioxidants in lactating dairy goats.

Improving Flavonoid Bioaccessibility using an Edible Oil-Based Lipid Nanoparticle for Oral Delivery

To enhance the oral bioaccessibility of flavonoids, including quercetin, naringenin, and hesperetin, we prepared an edible oil-based lipid nanoparticle (LNP) system. Flavonoid-loaded LNPs were similar to the blank LNP in physicochemical characteristics (z average <154.8 nm, polydispersity index <0.17, and ζ potential < -40.8 mV), and their entrapment efficiency was >81% at 0.3 wt % flavonoid concentration of the lipid phase. In the simulated digestion assay (mouth, stomach, and small intestine), LNPs were hydrolyzed under small intestine conditions and protected successfully incorporated flavonoids (≥94%). Moreover, the relative bioaccessibility of flavonoids was >71%, which was otherwise <15%, although flavonoids were released rapidly from LNPs into the medium. In conclusion, since the flavonoids incorporated in LNPs were preserved well during oral digestion and had improved bioaccessibility, the designed LNP system may serve as an encapsulation strategy to enhance the bioavailability of nonbioaccessible nutraceuticals in foods.

Enhancing the stability of lipid nanoparticle systems by sonication during the cooling step and controlling the liquid oil content

Aggregation of unstable particles in water limits the application of lipid nanoparticle (LNP) systems to foods despite the capability to encapsulate lipophilic bioactive components. This study exploits a preparation process that can reduce the aggregation of LNPs. Sonication during the cooling step (postsonication) for 4, 5, or 6 min was applied to increase the covering effect of Tween 20 on the particle. Additionally, LNPs were prepared using fully hydrogenated canola oil (FHCO) blended with 0-30 wt % liquid canola oil (LCO) of the lipid phase. Surfactant surface load data indicate that the postsonication might make nonemulsifying Tween 20 diffuse from the aqueous phase to droplet surfaces, which could decrease the crystallinity index (CI) of LNPs due to the inhibition of lipid crystallization. Moreover, the LCO content in lipid matrix could decrease the CI, which could reduce the formation of hydrophobic patches on the particle surface. Therefore, the postsonication and the LCO addition in the matrix could effectively prevent aggregation among hydrophobic patches. This improved colloidal stability of LNPs was verified by the particle shape in transmission electron microscopy and the gelation test. Consequently, LNPs fabricated using 6 min postsonication and 30 wt % LCO in the lipid exhibited the greatest stability (size, 202.3 nm; CI, 57.5%; Tween 20 surface load, 10.29 mg m(-2)). This study may serve as a basis for further research that aims to develop delivery systems for functional foods.

RNA - synthesis, purification and crystallization

Protocols for the routine chemical synthesis and purification of milligram quantities of RNA and DNA-RNA chimeras meeting the demands of X-ray crystallography are described. An efficient screening protocol to test the crystallizability of the molecules and the optimization of the crystallization conditions are presented, so as to allow reproduction by others. Essentially the same crystallization conditions as for DNA oligomers can be employed for RNA crystallization. Specific examples involving alternating octamers, G/C-rich decamers, sequences with overhangs, and drug complexes of chimeras are discussed. Success of the methods is attested by the crystals obtained which diffract to high resolution.

Eclamptic encephalopathy: MRI, including diffusion-weighted images

Eclampsia is a rare condition peculiar to pregnant and puerperal women. We analyse imaging features in five patients with eclampsia, and determine whether diffusion-weighted imaging (DWI) could differentiate cytotoxic and vasogenic oedema in four of them. All were imaged within 4 days of the onset of symptoms. We found lesions with a prolonged T2 in the brain of all five patients, in the basal ganglia in four, pons in three and posterior cerebral white matter in two. Isotropic DWI revealed variable intensity in these regions. The ADC was decreased in one, and increased in all the others. The lesion with reduced ADC progressed to infarction.

[Incidence of ocular trauma in Clinical Hospital Oradea between 1997-1999]

The purpose of the study is to analyse the great number of ocular injuries which were diagnosed and treated in the out-patients clinic or in the hospital in 1997-1999. Ocular trauma seems to be related to the working place or the main activities of the patients, such as agriculture or housekeeping. Ocular injuries in children are significant as number and prognosis. Blunt trauma, ocular perforations, ocular foreign bodies and burns were studied separately for children, housekeepers, unemployed, working and retired people. Due to their number and complexity, ocular trauma represent a very important part in the activity of an ophthalmology department. The conclusion of the study is the number of ocular injuries decreased over the years because of the reduced industrial activity in our town. Similar ocular injuries in retired and working people suggest that retired people are still active. The prognosis of ocular trauma is better if the patients come early to be seen by the specialist, if the treatment is adequate and if the department has a proper equipment for advanced surgery techniques.

[A myopia study of glaucoma patients following pilocarpine instillation]

AIM

Our research studies transitory myopia induced by Pilocarpine treatment in glaucoma patients.

MATERIAL AND METHODS

48 patients with open angle glaucoma were selected, visual acuity and refraction were measured before and after the instillation of Pilocarpine 2%, for two hours. Induced myopia was compared for different ages and it was established the influence of Timolol and Acetazolamide administered in the same time.

RESULTS

Transitory myopia is important in young patients, reduced after 50 years and absent after 70 years. Acetazolamide increases myopia, Timolol has no effect on refraction.

CONCLUSIONS

The study confirms the unpleasant effect of Pilocarpine and suggests not performing refractometry in the first two hours after the instillation of the drug.

Crystal structures of mismatch repair protein MutS and its complex with a substrate DNA

DNA mismatch repair is critical for increasing replication fidelity in organisms ranging from bacteria to humans. MutS protein, a member of the ABC ATPase superfamily, recognizes mispaired and unpaired bases in duplex DNA and initiates mismatch repair. Mutations in human MutS genes cause a predisposition to hereditary nonpolyposis colorectal cancer as well as sporadic tumours. Here we report the crystal structures of a MutS protein and a complex of MutS with a heteroduplex DNA containing an unpaired base. The structures reveal the general architecture of members of the MutS family, an induced-fit mechanism of recognition between four domains of a MutS dimer and a heteroduplex kinked at the mismatch, a composite ATPase active site composed of residues from both MutS subunits, and a transmitter region connecting the mismatch-binding and ATPase domains. The crystal structures also provide a molecular framework for understanding hereditary nonpolyposis colorectal cancer mutations and for postulating testable roles of MutS.

Oligomerization of a MutS mismatch repair protein from Thermus aquaticus

The MutS DNA mismatch protein recognizes heteroduplex DNAs containing mispaired or unpaired bases. We have examined the oligomerization of a MutS protein from Thermus aquaticus that binds to heteroduplex DNAs at elevated temperatures. Analytical gel filtration, cross-linking of MutS protein with disuccinimidyl suberate, light scattering, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry establish that the Taq protein is largely a dimer in free solution. Analytical equilibrium sedimentation showed that the oligomerization of Taq MutS involves a dimer-tetramer equilibrium in which dimer predominates at concentrations below 10 microM. The DeltaG(0)(2-4) for the dimer to tetramer transition is approximately -6.9 +/- 0.1 kcal/mol of tetramer. Analytical gel filtration of native complexes and gel mobility shift assays of an maltose-binding protein-MutS fusion protein bound to a short, 37-base pair heteroduplex DNA reveal that the protein binds to DNA as a dimer with no change in oligomerization upon DNA binding.

Transformation of MutL by ATP binding and hydrolysis: a switch in DNA mismatch repair

The MutL DNA mismatch repair protein has recently been shown to be an ATPase and to belong to an emerging ATPase superfamily that includes DNA topoisomerase II and Hsp90. We report here the crystal structures of a 40 kDa ATPase fragment of E. coli MutL (LN40) complexed with a substrate analog, ADPnP, and with product ADP. More than 60 residues that are disordered in the apoprotein structure become ordered and contribute to both ADPnP binding and dimerization of LN40. Hydrolysis of ATP, signified by subsequent release of the gamma-phosphate, releases two key loops and leads to dissociation of the LN40 dimer. Dimerization of the LN40 region is required for and is the rate-limiting step in ATP hydrolysis by MutL. The ATPase activity of MutL is stimulated by DNA and likely acts as a switch to coordinate DNA mismatch repair.

Crystal structure and ATPase activity of MutL: implications for DNA repair and mutagenesis

MutL and its homologs are essential for DNA mismatch repair. Mutations in genes encoding human homologs of MutL cause multiorgan cancer susceptibility. We have determined the crystal structure of a 40 kDa N-terminal fragment of E. coli MutL that retains all of the conserved residues in the MutL family. The structure of MutL is homologous to that of an ATPase-containing fragment of DNA gyrase. We have demonstrated that MutL binds and hydrolyzes ATP to ADP and Pi. Mutations in the MutL family that cause deficiencies in DNA mismatch repair and a predisposition to cancer mainly occur in the putative ATP-binding site. We provide evidence that the flexible, yet conserved, loops surrounding this ATP-binding site undergo conformational changes upon ATP hydrolysis thereby modulating interactions between MutL and other components of the repair machinery.

[Pseudophacos explant: the causes and the functional results]

We've studied a number of 20 cases of pseudophakic explantation performed in the Eye Center Timişoara between 1991-1997 from 2605 pseudophakic implantations. The interval between implantation and the moment of explantation was between 4 days and 7 years. The causes which indicated pseudophakic explantation were: pseudophakic bullous keratopathy, IOL decentration and dislocation, uveitis, persistent secondary glaucoma. The study refers to the established treatment for avoiding the explantation and also to the functional results obtained after pseudophakic explantation. Most of the explanted artificial lens cases were anterior chamber lens--13, all of them ALCON type, also we've explanted 4 pupillary implants Fedorov type. The visual acuities obtained after explantation were between hand movement perception and 10/10. Before surgery, visual acuity was between light perception and 10/10. The best functional results were obtained in pseudophakic decentration and dislocation cases and the worst in pseudophakic bullous keratopathy, uveitis and secondary glaucoma cases.

Structural basis for MutH activation in E.coli mismatch repair and relationship of MutH to restriction endonucleases

MutS, MutL and MutH are the three essential proteins for initiation of methyl-directed DNA mismatch repair to correct mistakes made during DNA replication in Escherichia coli. MutH cleaves a newly synthesized and unmethylated daughter strand 5' to the sequence d(GATC) in a hemi-methylated duplex. Activation of MutH requires the recognition of a DNA mismatch by MutS and MutL. We have crystallized MutH in two space groups and solved the structures at 1.7 and 2.3 A resolution, respectively. The active site of MutH is located at an interface between two subdomains that pivot relative to one another, as revealed by comparison of the crystal structures, and this presumably regulates the nuclease activity. The relative motion of the two subdomains in MutH correlates with the position of a protruding C-terminal helix. This helix appears to act as a molecular lever through which MutS and MutL may communicate the detection of a DNA mismatch and activate MutH. With sequence homology to Sau3AI and structural similarity to PvuII endonuclease, MutH is clearly related to these enzymes by divergent evolution, and this suggests that type II restriction endonucleases evolved from a common ancestor.

Crystal structure of d(GCGCGCG) with 5'-overhang G residues

The crystal structure of the DNA heptamer d(GCGCGCG) has been solved at 1.65 A resolution by the molecular replacement method and refined to an R-value of 0.184 for 3598 reflections. The heptamer forms a Z-DNA d(CGCGCG)2 with 5'-overhang G residues instead of an A-DNA d(GCGCGC)2 with 3'-overhang G residues. The overhang G residues from parallel strands of two adjacent duplexes form a trans reverse Hoogsteen G x G basepair that stacks on the six Z-DNA basepairs to produce a pseudocontinuous helix. The reverse Hoogsteen G x G basepair is unusual in that the displacement of one G base relative to the other allows them to participate in a bifurcated (G1)N2 . . . N7(G8) and an enhanced (G8)C8-H . . . O6(G1) hydrogen bond, in addition to the two usual hydrogen bonds. The 5'-overhang G residues are anti and C2'-endo while the 3'-terminal G residues are syn and C2'-endo. The conformations of both G residues are different from the syn/C3'-endo for the guanosine in a standard Z-DNA. The two cobalt hexammine ions bind to the phosphate groups in both GpC and CpG steps in Z(I) and Z(II) conformations. The water structure motif is similar to the other Z-DNA structures.

Crystal structure of an alternating octamer r(GUAUGUA)dC with adjacent G x U wobble pairs

The crystal structure of the RNA duplex, r(GUAUGUA)dC, with a 3'-terminal deoxy C residue, has been determined at 1.38 A resolution. The r(GUAUGU) hexameric consensus sequence is present at the exon-intron junction in pre-mRNAs of yeast and higher eukaryotic organisms. The crystal belongs to the rhombohedral space group R3. The hexagonal unit cell dimensions are a = b = 39.71 A, c = 68.15 A and gamma = 120 degrees with one duplex in the asymmetric unit. The structure was solved using the molecular replacement method. The final model contains 332 atoms of the duplex and 67 solvent molecules. The R-factor is 17.6% (Rfree of 23.1%) for 4035 reflections with F > or = 1.5sigma(F) in the resolution range 10.0 to 1.38 A. The duplex is of the A-type with a pseudodyad relating the two strands. The RNA helix is slightly distorted, in spite of the presence of two adjacent G x U wobble base-pairs located at the center of the helix. The twist angle between the wobble pairs, 38.1 degrees, is above the average value and those between the wobble base-pairs and the flanking Watson-Crick base-pairs, 26.7 degrees and 26.3 degrees, respectively, are lower than the average values. The twist between the junction base-pairs are about 24 degrees. The G x U wobble pairs are bridged by water molecules and solvated in the grooves. G x U base-pairs are as stable as the Watson-Crick A x U pairs and only slightly less stable than the G x C pairs accounting for their frequent occurrence in RNA.

Crystal structure of the self-complementary 5'-purine start decamer d(GCGCGCGCGC) in the Z-DNA conformation. I

Alternating self-complementary oligonucleotides starting with a 5'-pyrimidine usually form left-handed Z-DNA; however, with a 5'-purine start sequence they form the right-handed A-DNA. Here we report the crystal structure of the decamer d(GCGCGCGCGC) with a 5'-purine start in the Z-DNA form. The decamer crystallizes in the hexagonal space group P6(5)22, unit cell dimensions a = b = 18.08 and c = 43.10 A, with one of the following four dinucleotide diphosphates in the asymmetric unit: d(pGpC)/d(GpCp)/d(pCpG)/d(CpGp). The molecular replacement method, starting with d(pGpC) of the isomorphous Z-DNA hexamer d(araC-dG)3 without the 2'-OH group of arabinose, was used in the structure analysis. The method gave the solution only after the sugar-phosphate conformation of the GpC step was manipulated. The refinement converged to a final R value of 18.6% for 340 unique reflections in the resolution range 8.0-1.9 A. A result of the sequence alternation is the alternation in the nucleotide conformation; guanosine is C3'-endo, syn, and cytidine is C2'-endo, anti. The CpG step phosphodiester conformation is the same as ZI or ZII, whereas that of the GpC step phosphodiester is "intermediate" in the sense that zeta (O3'-P bond) is the same as ZII but alpha (P-O5' bond) is the same as ZI. The duplexes generated from the dinucleotide asymmetric unit are stacked one on top of the other in the crystal to form an infinite pseudocontinuous helix. This renders it a quasi-polymerlike structure that has assumed the Z-DNA conformation further strengthened by the long inner Z-forming stretch d(CG)4. An interesting feature of the structure is the presence of water strings in both the major and the minor grooves. In the minor groove the cytosine carbonyl oxygen atoms of the GpC and CpG steps are cross-bridged by water molecules that are not themselves hydrogen bonded but are enclosed by the water rings in the mouth of the minor groove. In the major groove three independent water molecules form a zigzagging continuous water string that runs throughout the duplex.

Crystal structure of the self-complementary 5'-purine start decamer d(GCACGCGTGC) in the A-DNA conformation. II

The crystal structure of the alternating 5'-purine start decamer d(GCGCGCGCGC) was found to be in the left-handed Z-DNA conformation. Inasmuch as the A.T base pair is known to resist Z-DNA formation, we substituted A.T base pairs in the dyad-related positions of the decamer duplex. The alternating self-complementary decamer d(GCACGCGTGC) crystallizes in a different hexagonal space group, P6(1)22, with very different unit cell dimensions a = b = 38.97 and c = 77.34 A compared with the all-G.C alternating decamer. The A.T-containing decamer has one strand in the asymmetric unit, and because it is isomorphous to some other A-DNA decamers it was considered also to be right-handed. The structure was refined, starting with the atomic coordinates of the A-DNA decamer d(GCGGGCCCGC), by use of 2491 unique reflections out to 1.9-A resolution. The refinement converged to an R value of 18.6% for a total of 202 nucleotide atoms and 32 water molecules. This research further demonstrates that A.T base pairs not only resist the formation of Z-DNA but can also assist the formation of A-DNA by switching the helix handedness when the oligomer starts with a 5'-purine; also, the length of the inner Z-DNA stretch (d(CG)n) is reduced from an octamer to a tetramer. It may be noted that these oligonucleotide properties are in crystals and not necessarily in solutions.

Structure of the Purine–Pyrimidine Alternating RNA Double Helix, r(GUAUAUA)d(C), with a 3'-Terminal Deoxy Residue

The crystal structure of the purine-pyrimidine alternating octameric RNA helix, r(GUAUAUA)d(C), carrying a 3'-terminal deoxycytidine residue, has been determined at 2.2 A resolution. The molecule crystallizes in the rhombohedral space group R3 (hexagonal cell constants: a = b = 43.07,c = 59.36 A;alpha = beta = 90,gamma = 120 degrees )with one duplex in an asymmetric unit. The structure was solved by molecular replacement and refined with 83 and 2/3 solvent molecules and 2/3 sodium ions to a final R factor of 15.6% using 1775 reflections (86%). The duplexes are approximately linear, their global helix axes are inclined by 10 degrees with respect to the 3(2)-screw axes, and they are stacked on top of each other in a head-to-tail fashion. The twist between the junction base pairs of the stacked duplexes is negligible resulting in a discontinuity of the helix backbones and grooves. The sodium ions on the threefold axis play a significant role in the organization of the packing network. The helical parameters, particularly the twist and the roll, of this alternating sequence are in accord with Calladine's rules. Almost all the 2'-hydroxyl groups are involved in specific hydrogen-bonding interactions, either directly to the sugar ring oxygens O4' on the 3' side, or, through water bridges, to the sugars, phosphates, or bases. This hydrogen bonding of the 2'-hydroxyl groups restrains the conformation of the sugar-phosphate backbone and the glycosidic torsion angles of this RNA fragment. The lack of intermolecular packing contacts in the grooves provides a clear picture of the groove solvation.

Crystal structure of the highly distorted chimeric decamer r(C)d(CGGCGCCG)r(G).spermine complex--spermine binding to phosphate only and minor groove tertiary base-pairing

The crystal structure of the self-complementary chimeric decamer duplex r(C)d(CGGCGCCG)r(G), with RNA base pairs at both termini, has been solved at 1.9 A resolution by the molecular replacement method and refined to an R value of 0.145 for 2,314 reflections. The C3'-endo sugar puckers of the terminal riboses apparently drive the entire chimeric duplex into an A-DNA conformation, in contrast to the B-DNA conformation adopted by the all-deoxy decamer of the same sequence. Five symmetry related duplexes encapsulate a spermine molecule which interacts with ten phosphate groups, both directly and through water molecules to form multiple ionic and hydrogen bonding interactions. The spermine interaction severely bends the duplexes by 31 degrees into the major groove at the fourth base pair G(4).C(17), jolts it and slides the 'base plate' into the minor groove. This base pair, together with the adjacent base pair in the top half and the corresponding pseudo two-fold related base pairs in the bottom half, form four minor groove base-paired multiples with the terminal base pairs of two neighboring duplexes.

A single 2'-hydroxyl group converts B-DNA to A-DNA. Crystal structure of the DNA-RNA chimeric decamer duplex d(CCGGC)r(G)d(CCGG) with a novel intermolecular G-C base-paired quadruplet

We have found that the introduction of a single 2'-hydroxyl group on the sugar-phosphate backbone of the B-DNA decamer d(CCGGCGCCGG) transforms it to A-DNA. Thus, for the first time the X-ray structures of the same sequence have been observed in both the A and B-DNA conformations, permitting a comparison. Crystals of the DNA-RNA chimeric decamer d(CCGGC)r(G)d(CCGG) belong to the orthorhombic space group P2(1)2(1)2(1) with unit cell dimensions a = 25.63 A, b = 45.24 A and c = 47.99 A, and one decamer duplex in the asymmetric unit. The structure was solved by a rigid body search using the coordinates of the isomorphous structure d(CCCGGCCGGG) and refined to an R value of 0.136 using 2753 unique reflections at 1.9 A resolution. The final model contains 406 nucleotide atoms and 61 water molecules. The chimeric duplex exhibits typical A-DNA geometry, with all the sugars in the C(3')-endo puckering and the base-pairs inclined and displaced from the helix axis. The 2'-hydroxyl groups on rG6 and rG16 protrude into the minor groove surface and form different types of hydrogen bonds; that on strand 1 forms an intermolecular hydrogen bond with the furanose ring O(4') of a symmetry-related C1 residue, while that on strand 2 is involved in two water bridges. Crystal packing forces the G4-G17 base-pair in the top half of the duplex to slide significantly into the minor groove compared to the corresponding G7-G14 base-pair in the bottom half, resulting in these base-pairs exhibiting different base stacking and intermolecular interactions. The base G4 of the G4-G17 base-pair forms an unorthodox base "triple", G4*(G10-C11), hydrogen-bonding through its minor groove sites N(2) and N(3) to the minor groove atoms N(2) and O(2) of both bases of the G10-C11 base-pair of a symmetry-related molecule. The base G10 of this triple in turn forms a second similar unorthodox base triple, G10*(G3*C18), with the adjacent base-pair G3-C18 of the duplex, thus G10 is involved in a double triple. On the other hand, in the bottom half of the duplex, the C7-G14 base-pair is involved only in a single similar unorthodox base triple with G20, (C7-G14)*G20, while the adjacent base-pair rG6-C15 is involved in a novel quadruple with C1-G20, (rG6-C15) *(C1-G20), where the latter base-pairs are hydrogen-bonded to each other via the minor groove sites G(N(2))...C(O(2)).(ABSTRACT TRUNCATED AT 400 WORDS)

Structure of the recombinantParamecium tetraureliacalmodulin at 1.68 Å resolution

The crystal structure of the recombinant calmodulin from Paramecium tetraurelia (rPCaM, M(r) = 16 700, 148 residues) has been determined at 1.68 A resolution. X-ray intensity data were collected at 263 K using a Siemens-Nicolet area detector and Cu Kalpha radiation from a rotating-anode source. A total of 35 936 observations were processed with XENGEN1.3 and scaled to yield 16 255 unique reflections with R(symm)(I) of 4.1%. The crystals are triclinic, with unit-cell dimensions a = 29.89, b = 53.42, c = 25.35 A, alpha = 93.67, beta = 96.88, gamma = 89.24 degrees, space group P1, with one molecule in the unit cell. The atomic coordinates of the wild-type Paramecium calmodulin (PCaM) studied in our laboratory provided the starting model. Refinement of the structure by X-PLOR and refitting it into omit maps yielded an R value of 0.194 for 15 965 reflections greater than 3sigma(F) in the 6.0-1.68 A resolution range. The final model contained 1165 protein atoms for all of the 148 residues, four Ca(2+) ions, and 172 water molecules. The dumbbell structure has seven alpha-helices including a long 7.8 turn central helix connecting the two terminal domains each containing two EF-hand (helix-loop-helix motif) calcium-binding sites. The loops within each pair of EF-hand motifs in the N- and C-terminal domains are brought into juxtaposition to form a pair of hydrogen-bonded antiparallel beta-sheets which are extended at either ends by water bridges. The four calcium-binding EF-hands are superposable with r.m.s. deviations of 0.31-0.79 A. The best agreement is between site 1 and site 3 and the worst agreement is between site 1 and 4. The largest differences are in the ninth and tenth residues of the calcium-binding loops probably because of their involvement in the mini beta-sheets. The calcium coordination distances vary between 2.04 and 2.69 A, average 2.34 A. The rPCaM and wild-type PCaM have an r.m.s. deviation of 0.36 A for equivalent C(alpha) atoms. The side chains of Lys13 and Lys115 are more extended in rPCaM compared to the wild type where the post-translational modified di- and tri-methylated lysine residues are more folded. The sequence of PCaM differs from those of mammalian (MCaM) and Drosophila calmodulin (DCaM), but the overall structures are very similar, with r.m.s,. deviations of 0.44 and 1.68 A for equivalent C(alpha) atoms, respectively. However, in rPCaM, the first four N-terminal residues stretch out and make intermolecular crystal contacts, in contrast to those in recombinant Drosophila calmodulin (rDCaM), they stretch out in the opposite direction and towards the second calcium-binding site (see note below), while in MCaM and wild-type PCaM, the N-terminal residues are not visible. The central helix in rPCaM has all its backbone hydrogen bonds intact with no unusually long separation between the carbonyl and amide groups as found in MCaM and rDCaM.