Multidimensional features of sporadic Creutzfeldt-Jakob disease in the elderly: a case report and systematic review.

Background: As a rare neurodegenerative disease, sporadic Creutzfeldt-Jakob disease (sCJD) is poorly understood in the elderly populace. This study aims to enunciate the multidimensional features of sCJD in this group. Methods: A case of probable sCJD was reported in a 90-year-old Chinese man with initial dizziness. Then, available English literature of the elderly sCJD cases (aged 80 years and over) was reviewed and analyzed. Patients (15 cases) were subdivided and compared geographically. Results: In the elderly sCJD cohort, the onset age was 84.9 ± 4.5 years and the median disease duration was 6.8 months, with respiratory infection/failure as the commonest death cause. Various clinical symptoms were identified, with cognitive disorder (86.7%) as the commonest typical symptom and speech impairment (66.7%) as the most atypical one. Restricted hyperintensities were reported in 60.0% cases on DWI, periodic sharp wave complexes in 73.3% cases on electroencephalogram, and cerebral hypoperfusion/hypometabolism in 26.7% cases on molecular imaging. The sensitive cerebrospinal fluid biomarkers were total tau (83.3%), 14-3-3 protein (75.0%), and PrP RT-QuIC (75.0%). Neuropathological profiles in the cerebral cortex revealed vacuolar spongiosis, neuronal loss, gliosis, and aging-related markers, with synaptic deposit as the commonest PrP pattern (60.0%). The polymorphic PRNP analysis at codon 129 was M/M (90.9%), with MM1 and MM2C as the primary molecular phenotypes. Latency to first clinic visit, hyperintense signals on DWI, and disease duration were significantly different between the patient subgroups. Conclusion: The characteristics of sCJD are multidimensional in the elderly, deepening our understanding of the disease and facilitating an earlier recognition and better care for this group.

Short-term steaming during processing impacts the quality of Citri Reticulatae 'Chachi' peel.

Citrus peel is a commonly used food-medicine material in the production of fast-moving consumer goods (FMCGs). For instance, Ganpu tea is manufactured by combining the peel of Citri Reticulatae 'Chachi' (PCRC) with Pu-erh tea. The alleviated irritation of PCRC through years of aging makes Citri reticulatae Pericarpium a traditional Chinese medicine. Herein, we introduced short-term steaming into the processing of PCRC to favor the quick removal of its irritation while retaining its food-medicine properties. Sensory evaluation and volatile component analysis showed that 60-s steaming reduced irritation of freshly prepared PCRC. Biological evaluations indicated no effects of steaming on the neuroprotective activity of PCRC. The process increased the contents of several bioactive ingredients, including hesperidin, nobiletin, tangeretin, and synephrine. In addition, physical indications of accelerating PCRC aging were observed. Taken together, our findings suggest that short-term steaming may offer a promising new possibility for enhancing the quality of citrus peel.

Enzymatic treatment to improve permeability and quality of cherry tomatoes for production of dried products.

BACKGROUND: Cherry tomatoes are nutritious and favored by consumers. Processing them into dried cherry tomatoes can prolong their storage life and improve their flavor. The pretreatment of tomato pericarp is crucial for the subsequent processing. However, the traditional physical and chemical treatments of tomato pericarp generally cause nutrient loss and environmental pollution. RESULTS: In this study, a novel enzymatic method for cherry tomatoes was performed using mixed enzymes containing cutinase, cellulase and pectinase. Results showed that the pericarp permeability of cherry tomatoes was effectively improved due to enzymatic treatment. Changes in the microscopic structure and composition of the cuticle were revealed. After treatment with different concentrations of enzymes, cherry tomatoes exhibited higher pericarp permeability and sensory quality to varying degrees. The lycopene content and total polyphenol content significantly increased 2.4- and 1.45-fold, respectively. In addition, the satisfactory effect of the six-time reuse of enzymes on cherry tomatoes could still reach the same level as the initial effect, which effectively reduced the cost of production. CONCLUSIONS: This study revealed for the first time that a mixed enzymatic treatment consisting of cutinase, pectinase and cellulase could effectively degrade the cuticle, enhance the pericarp permeability and improve the quality of cherry tomatoes, with the advantages of being mildly controllable and environmentally friendly, providing a new strategy for the processing of dried cherry tomatoes. © 2023 Society of Chemical Industry.

[Expression, thermal stability modification and application in PHB degradation of polyhydroxyalkanoate depolymerase from Thermomonospora umbrina].

Polyhydroxyalkanoate depolymerase (PHAD) can be used for the degradation and recovery of polyhydroxyalkanoate (PHA). In order to develop a PHAD with good stability under high temperature, PHAD from Thermomonospora umbrina (TumPHAD) was heterelogously expressed in Escherichia coli BL21(DE3). At the same time, a mutant A190C/V240C with enhanced stability was obtained via rational design of disulfide bonds. Characterization of enzymatic properties showed that the mutant A190C/V240C had an optimum temperature of 60 ℃, which was 20 ℃ higher than that of the wild type. The half-life at 50 ℃ was 7 hours, at 50 ℃ which was 21 times longer than that of the wild type. The mutant A190C/V240C was used for the degradation of polyhydroxybutyrate (PHB), one of the typical PHA. At 50 ℃, the degradation rate of PHB being treated for 2 hours and 12 hours was 2.1 times and 3.8 times higher than that of the wild type, respectively. The TumPHAD mutant A190C/V240C obtained in this study shows tolerance to high temperature resistance, good thermal stability and strong PHB degradation ability, which may facilitate the degradation and recovery of PHB.

Mechanistic Insights into How the Protonation State of D234 Dictates the Reactivity in Streptomyces coelicolor ß-N-Acetylhexosaminidase.

ß-N-Acetylhexosaminidases (HEXs) play important roles in human diseases and the biosynthesis of human milk oligosaccharides. Despite extensive research, the catalytic mechanism of these enzymes remains largely unexplored. In this study, we employed quantum mechanics/molecular mechanics metadynamics to investigate the molecular mechanism of Streptomyces coelicolor HEX (ScHEX), which has shed light on the transition state structures and conformational pathways of this enzyme. Our simulations revealed that Asp242, located near the assisting residue, can switch the reaction intermediate to an oxazolinium ion or a neutral oxazoline, depending on the protonation state of the residue. Moreover, our findings indicated that the free energy barrier of the second-step reaction starting from the neutral oxazoline increases steeply due to the reduction in the anomeric carbon positive charge and the shortening of the C1-O2N bond. Our results provide valuable insights into the mechanism of substrate-assisted catalysis and could facilitate the design of inhibitors and the engineering of analogous glycosidases for biosynthesis.

Synergism in sequential inactivation of Cryptosporidium parvum with trypsin and UV irradiation.

Cryptosporidium, a protozoan parasite, in wastewater presents a major public health concern for water safety. However, bactericidal efficiencies of conventional disinfection methods towards Cryptosporidium oocysts are still hampered owing to the presence of their thick outer wall. In this study, we present a novel UV inactivation process where the efficiency has been significantly enhanced by addition of a trypsin pretreatment stage. Notably, inactivation (log-reduction) of oocysts was noted to be 73.75-294.72% higher than that obtained by UV irradiation alone, under identical conditions. Experimental observations and supporting mechanistic analyses suggest that trypsin led to cleavage of the protein layers on the oocyst wall, facilitating penetration of UV radiation into the oocysts leading to degradation of their genomic DNA (gDNA). The dissociative effect of trypsin on the oocyst wall was indicated by the fact that 64.50% of oocysts displayed early apoptosis after trypsinization. Imaging by scanning electron microscopy indicated that this combined treatment led to substantial disruption of the oocyst coat, deforming their shape. This resulted in the release of cellular proteins and gDNA, their concentrations in bulk solution increasing by 1.22-8.60 times. As UV irradiation time was prolonged, gDNA was degraded into smaller fragments with lower molecular masses. Both laddering and diffuse smear patterns in gel analysis indicated significantly detrimental effects on gDNA and viability of oocysts. Overall, this study demonstrated enhancement of UV inactivation of Cryptosporidium oocysts by trypsin and explored the underlying mechanisms for the process.

3D nanocrystalline metal-organic framework materials for the improved output performance of triboelectric nanogenerators.

Triboelectric nanogenerators (TENGs) based on contact electrification and electrostatic induction can effectively convert low-frequency mechanical energy into electrical energy and has attracted considerable attention. However, the low current output performance seriously hinders the wide application of TENGs. Herein, a 3D nanocrystalline metal-organic framework (Cd-MOF) with a specific structure and morphology was reasonably designed as a high-performance triboelectric positive electrode material. The triboelectric test results showed that the maximum instantaneous short-circuit current of Cd-MT was 55.32 µA and the stable output performance maintained a long-term continuous operation for 10 000 s. The peak values of the charge density and electric power density were 102.39 µC m-2 and 2451.04 mW m-2, respectively. In addition, the Cd-MT could quickly fully charge commercial capacitors and light a large number of LED lamps. This work provides a new idea for the development and design of functional MOF triboelectric materials.

Simultaneous Improvement of Final Product-Tolerance and Thermostability of GH39 Xylosidase for Prebiotic Production by Directed Evolution.

Xylosidases are widely used for the production of prebiotics and the transformation of natural active substances in the food industry. However, xylosidases with excellent thermostability and product tolerance are required for industrial applications. In this study, the thermostability and final-product tolerance of the previously reported robust xylosidase Xyl21 were further improved via directed evolution. The triple mutant variant Xyl21-A16 (K16R, L94I, and K262N) showed significantly enhanced xylose tolerance, ethanol tolerance, and thermostability with no apparent changes in the specific activity, optimum pH, and temperature compared with the wild type. Single site mutations suggested that variant Xyl21-A16 is the cumulative result of three mutated sites, which indicated that K16 and L94 play important roles in enzyme characteristics. Moreover, a comparison of the predicted protein structures of Xyl21 and its variant indicated that additional molecular interactions formed by K16R and K262N might directly improve the rigidity of the protein structure, therefore contributing to the increased thermostability and product tolerance. The variant Xyl21-A16 developed in this study has great application potential in the production of prebiotics, and also provides a useful reference for the future engineering of other xylosidases.

[Determination of new carmine in beverages by one step rapid solid phase extraction based on metal organic framework extractant].

New coccine is an azo pigment that is widely used in food. To mitigate potential health issues arising from excessive consumption, China has issued provisions on the allowed addition limit of new coccine in food. Currently, there are certain difficulties with establishing detection methods for such trace pigments in foods; for example, preprocessing is complex and time-intensive. In addition, the low content of the target substance in the sample could be disturbed by food matrix, resulting in poor detection sensitivity. Metal organic frameworks (MOFs), as a novel class of highly efficient adsorbents, have attracted increasing attention because of their stability and large specific surface area. MOFs are porous coordination crystal structures that connect metal clusters with organic ligands via coordination. Owing to their molecule-sized pores, MOFs can be used in various fields such as adsorption, catalysis, and drug dispersion. However, at the same time, their ultra-high specific surface area also leads to ultra-low weight of the material itself; this makes it difficult to collect the material even under high-speed centrifugation. In this study, a MOF material (PCN-222) with a high specific surface area was prepared by the coordination of the carboxyl group in the porphyrin ring and metal zirconium ions. To simplify pretreatment, the nanomaterials were filled into an injection solid phase extraction device for the rapid extraction of new coccine pigments from beverages. The morphology, structure, and properties of the PCN-222 nanomaterials were studied by transmission electron microscopy, particle size analysis, X-ray single-crystal diffraction, infrared spectroscopy, and ultraviolet spectroscopy. The specific surface area of the synthesized material was 979 m2/g. A high specific surface area was conducive to the adsorption of trace target compounds. The surface charge of the material could be controlled by adjusting the pH value of the solution, which was beneficial to the selective adsorption and desorption of ionic pigments. The π-π interaction between the benzene ring of the porphyrin ring and the benzene ring of the azo pigment also promoted extraction. Thus, the extractant exhibited strong enrichment performance for the new coccine anionic pigment. The solid phase extraction conditions were optimized, and it was found that saturated adsorption capacity was achieved by filling 3 mg of extractant. The effect of pH on adsorption was also explored; the adsorption effect was the best at pH 3. In the desorption experiment, N,N-dimethylformamide at pH 11 was conducive to better elution of the target. Further elution volume studies showed that maximum recovery could be achieved by adding 3 mL of eluent. Subsequently, the sample pretreatment time was reduced to 5 min. The enriched sample was separated using a Zorbax eclipse XDB-C18 column (250 mm×4.6 mm, 5 µm), eluted with an ammonium acetate-methanol solvent system, and detected at 254 nm. Under the optimum conditions, the recoveries of the samples at high, medium, and low levels reached 99.5%-109.4%, and the relative standard deviation was less than 3%. The limit of detection (LOD, S/N=3) of this method was 0.1 µg/L and the limit of quantification (LOQ, S/N=10) was 0.3 µg/L. In the actual sample detection experiment, the detection signal of new coccine in the sample was amplified by solid phase extraction to achieve enrichment. In addition, the extraction capacity of PCN-222 remained higher than 90% after four uses, and the synthesized material could be recycled. The high precision and low detection limit indicate that the method is suitable for the enrichment and detection of trace carmine in beverages. The findings of this study will aid in the development of a new solid phase extraction technology for food safety evaluation.

Biochemical characterization of a novel halo/organic-solvents/final-products tolerant GH39 xylosidase from saline soil and its synergic action with xylanase.

Xylosidases with tolerance to high concentration of salts, organic solvents, and enzyme hydrolytic products are preferential for industrial application but were rarely reported. In this study, a novel xylosidase XYL21 belong to glycoside hydrolase 39 was characterized with optimal temperature of 45 °C and optimal pH of 5.50. Different to other GH39 xylosidases, XYL21 had excellent tolerance to salts, the activity of which is not inhibited but slightly increased in 0.50-1.50 M NaCl. It is also tolerant to organic solvents, especially retaining 105.18% relative activity even in the presence of 15.00% (v/v) ethanol. Moreover, XYL21 was insensitive to the final lignocellulose hydrolysis products including glucose, xylose, arabinose, mannose and galactose, which retains 111.36% and 53.49% relative activity in 0.30 and 0.90 M xylose, respectively. Further structural modeling analysis indicated that its excellent tolerance may be attributed to its high structural flexibility caused by the high proportion of random coils. Furthermore, XYL21 had a wide substrate specificity to catalyze xylan and xylo-oligosaccharides, and it significantly cooperated with xylanase to improve the hydrolysis efficiency with 1.52-fold. Considering these unique properties, XYL21 is a good candidate for both basic research and various potential industrial applications such as seafood processing and bioethanol production.

The critical roles of exposed surface residues for the thermostability and halotolerance of a novel GH11 xylanase from the metagenomic library of a saline-alkaline soil.

Thermostable and halotolerant GH11 xylanases are highly desirable in various industrial applications but they were rarely characterized. In this study, we firstly revealed the genetic diversity of GH11 xylanases from the metagenomic DNA of a saline-alkaline soil by constructing a gene fragment library. Twelve distinct xylanase fragment sequences were identified, which shared 62-96% identity to known GH11 xylanases. Among them, Xyn22 with the highest relative abundance was cloned and found to exhibit excellent halotolerance. Xyn22 retained 80 and 58% relative activity in the presence of 3 and 5 M NaCl, respectively, and had no loss of activity after incubation in 3 M NaCl at 37 °C for 1 h. Additionally, the acidic amino acid residues E137 and E139 on the protein's surface were revealed to cooperatively play important roles in its excellent halotolerance and halostabilty. Furthermore, the thermostability of Xyn22 was significantly improved without compromising halotolerance by introducing an aromatic interaction between Y48 and F53. In conclusion, this study not only provides a thermostable and halotolerant GH11 xylanase, but also reveals the key roles of surface-exposed amino acids in its thermostability and halotolerance, which could be used for further molecular modification of other xylanases and similar enzymes.

Novel pyridinium-based tags: synthesis and characterization for highly efficient analysis of thiol-containing peptides by mass spectrometry.

In this study, a novel type of pyridinium-based tags, 1-[3-[(2-iodo-1-oxoethyl)amino]propyl]-4-methylpyridinium bromide (IMP) and 1-[3-[(2-iodo-1-oxoethyl)amino]propyl]-4-propylpyridinium bromide (IPP), were designed, synthesized, and applied to the derivatization of thiol-containing peptides. With model peptides as the sample, the labeling efficiency and the stability of the peptide derivatives were investigated. The results indicate that nearly 100% derivatization yield was achieved with the developed tags and the peptide derivatives were stable at room temperature for at least one week. Furthermore, improved ionization efficiency and increased charge states were achieved via both matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MS) and electrospray ionization (ESI) MS, of which IPP exhibited the more obvious improvement of ionization efficiency. Further analysis of tryptic digests of bovine serum albumin (BSA) and α-transferrin, showed that increased identification efficiency of the thiol-containing peptides was achieved by combination with IMP or IPP derivatization. For example, the identification efficiency of the thiol-containing peptides of α-transferrin increased more than 42% upon combination with the IMP or IPP derivatives. We anticipate the novel tags are promising for highly efficient thiol-containing peptide identification in proteome research, especially for low concentrations.

Study of the surface ionization detector for gas chromatography.

The structure of the surface ionization detector (SID) and the operation parameters of GC-SID were investigated to reduce peak tailing and to enhance sensitivity. The performances of the GC-SID, including its repeatability, linearity, sensitivity, selectivity, and tolerance towards water vapor, were evaluated systematically. Compared with nitrogen-phosphorus detector (NPD), the SID was able to detect fg level triethylamine, and selectively respond to alkylamines, some anilines, and some nitrogen heterocyclic compounds. Among alkylamines, the SID sensitivity to diisobutylamine was rather small. Even so, it was also still 10 times higher than that on NPD. The SID selectivity, defined as the sensitivity ratio between triethylamine and various tested non-nitrogen compounds, was higher than 10(6). It was found that the SID is highly tolerant towards water vapor, allowing direct injection of water sample. Finally, the GC-SID was applied to directly measure trace amines in headspace gases of rotted meat and trace simazine in tap water. The SID sensitivity to simazine was proven to be 5 times higher than that on flame ionization detector (FID). This study suggests that the SID is a promising GC detector.

[Determination of nitrogen compounds in gasoline by gas chromatography-surface ionization detector].

Nitrogen compounds in gasoline were extracted by liquid-liquid extraction and analyzed by gas chromatography-surface ionization detector (GC-SID). Compared with the chromatograms obtained from GC-flame ionization detector (FID), GC-thermal ionization detector (NPD) and GC-mass spectrometry (MS), the peaks in the chromatogram obtained by GC-SID were assigned to the nitrogen compounds in gasoline. Most of these nitrogen compounds could not be detected by FID or NPD, which demonstrated the high selectivity and sensitivity of the SID. The types of nitrogen compounds in three gasoline samples (90#, 93#, 97#) were similar, but their contents varied with different gasoline brands. The extracted nitrogen compounds were mainly anilines, the amounts of which in the three gasoline samples were different. Trace amounts of several high boiling point nitrogen compounds were successfully detected because of the high sensitivity of SID. The SID is superior to the commercial NPD in detecting the nitrogen compounds in gasoline samples. In view of its high sensitivity and selectivity, the SID is a promising GC detector.

Temperature-controlled headspace liquid-phase microextraction device using volatile solvents.

A novel temperature-controlled headspace liquid-phase microextraction (TC-HS-LPME) device was established in which volatile solvents could be used as extractant. In this device, a PTFE vial cap with a cylindrical cavity was used as the holder of the extraction solvent. Up to 40 microl of extraction solvent could be suspended in the cavity over the headspace of aqueous sample in the vial. A cooling system based on thermoelectric cooler (TEC) was used to lower the temperature of extractant in PTFE vial cap to reduce the loss of volatile solvent during extraction process and increase the extraction efficiency. The selection of solvents for HS-LPME was then extended to volatile solvents, such as dichloromethane, ethyl acetate and acetone. The use of volatile extraction solvents instead of semi-volatile solvent reduced the interference of the large solvent peak to the analytes peaks, and enhanced the compatibility of HS-LPME with gas chromatograph (GC). Moreover, the use of larger volume of extractant solvent increases the extraction capacity and the injection volume of GC after extraction, thus improving detection limits. Several critical parameters of this technique were investigated by using chlorobenzenes (CBs) as the model analytes. High enrichment factors (498-915), low limits of detection (0.004-0.008 microg/L) and precision (3.93-5.27%) were obtained by using TC-HS-LPME/GC-FID. Relative recoveries for real samples were more than 83%.

A fiber-optic evanescent wave O2 sensor based on Ru(II)-doped fluorinated ORMOSILs.

A novel fiber-optic evanescent wave sensor (FOEWS) for O(2) detection based on [Ru(bpy)(3)](2+)-doped hybrid fluorinated ORMOSILs (organically modified silicates) has been developed. The sensing element was fabricated by dip-coating the optical fiber with [Ru(bpy)(3)](2+)-doped hybrid fluorinated ORMOSILs composed of n-propyltrimethoxysilane (n-propyl-TriMOS) and 3, 3, 3-trifluoropropyltrimethoxysilane (TFP-TriMOS). Fluorophores of [Ru(bpy)(3)](2+) were excited by the evanescent wave field produced on the fiber core surface and the emission fluorescence was quenched by O(2). Spectroscopic properties have been characterized by FTIR and UV-VIS absorption measurements. By using the presented hybrid fluorinated ORMOSILs, which enhances the coating surface hydrophobicity, the quenching response is increased. The sensitivity of the sensor is 7.5, which is quantified in terms of the ratio I (N2)/I (O2) (I (N2) and I (O2) represent the fluorescence intensities in pure N(2) and pure O(2) environments, respectively). The limit of detection (L.O.D.) is 0.01% (3sigma) and the response time is about 1 s. Meanwhile, the proposed FOEWS has the advantages of easy fabrication, low cost, fast response and suitable sensitivity for oxygen monitoring using a cheap blue LED as light source and coupling a miniature PMT detector directly to the optical fiber probe.

A glycerol assisted light-emitting diode-induced fluorescence detector for capillary flow systems.

A glycerol assisted light-emitting diode (LED)-induced fluorescence detector (IF) for capillary flow systems was constructed and evaluated. A blue LED was used as the excitation source, and optical fibers (OF) were used to transmit the excitation light and collect the fluorescence. A commercial available 5-port manifold was used as detection cell, where the capillary tube and the OF were fixed into the manifold. The precision of the holes on the manifold ensured a self-alignment of optical path. A refractive index matching fluid (RIMF)-glycerol was used to eliminate the interfaces between the OF and the LED, as well as between the fused silica capillary and the transmitting/collecting fiber. The enhancement of excitation light led to 2.8-folds improvement on the signal-to-noise ratio. The use of RIMF also eliminates focusing effect of the capillary wall and reduces both the excitation light directed to the detection cell and background signal, resulting in reduction in the fluorescence intensity and noise level. The intensity was reduced to 47-63% for laser and 60-77% for LED, respectively, for capillaries with i.d. from 50 to 250 microm; while the noise level was reduced to 1/3 when RIMF was used for both laser and LED on the tested capillaries. About 5.6-fold enhancement in signal-to-noise ratio was obtained in total. The detection limit of the LED-IF for fluorescein isothiocyanate (FITC) was 4 nM. Application of the LED-IF for the analysis of FITC-labeled amino acids by electrophoresis was demonstrated.

A lamp light-emitting diode-induced fluorescence detector for capillary electrophoresis.

A light-emitting diode-induced fluorescence detector (LED-FD) for capillary electrophoresis was constructed and evaluated. A lamp LED with an enhanced emission spectrum and a band pass filter was used as the excitation light source. Refractive index matching fluid (RIMF) was used in the detection cell to reduce scattering light and the noise level. The limit of detection (LOD) for fluorescein was 1.5 nM (SNR=3). The system exhibited linear responses in the range of 1 x 10(-8) to 5 x 10(-6)M (R=0.999). Application of the lamp LED-FD for the analysis of FITC-labeled ephedra herb extract by capillary electrophoresis was demonstrated.

[High-performance liquid chromatography-mass spectrometry for determining olmesartan in human plasma].

OBJECTIVE: To establish a simple and rapid HPLC-MS method for determining the contents of olmesartan in human plasma. METHODS: Plasma were precipitated with trifluoroacetic acid, then analyzed on an HyPurity C(18) column (150 mm 2.1 mm, 5 microm). Samples at 40 degrees celsius;. The mobile phase consisted of water-methanol- acetonitrile(14:60:26) with a flow rate of 0.22 ml/min. RESULTS: The lower limit of qualification was 25 microg/L. The calibration curve was linear over the range of 25-3200 microg/L (r=0.9998), with the intra-day and inter-day RSD less than 15%. CONCLUSION: The method is sensitive, rapid and suitable for the study of pharmacokinetics and bioavailability of olmesartan.