Silver nanoparticles-based localized surface plasmon resonance biosensor for Escherichia coli detection

Escherichia coli (E. coli) bacteria with varying solution concentrations have been successfully detected using silver nanoparticles (Ag NPs)-based localized surface plasmon resonance (LSPR) biosensors. The Ag NPs were effectively synthesized by a chemical method using trisodium citrate with L-Histidine (L-His) and deposited on the surface of Au thin film-coated half-cylinder BK-7 prisms. He-Ne laser with a wavelength of 632.8 nm was used to generate LSPR phenomena in Kretschmann configuration with prism/Au thin film/His-Ag NPs/E. coli bacteria/air structure arrangements. The variation of E. coli bacteria concentration was carried out to determine the effect of E. coli bacteria concentration on the LSPR curve characteristics. The characterization results showed that the size of Ag NPs was 18.7 nm, and that of His-Ag NPs was 17.9 nm. Selected area electron diffraction results indicated the formation of diffraction rings with the presence of lattice planes (111), (200), (220), and (311), proving the face-centered cubic crystal structure of silver. The absorbance peak of Ag NPs shifted from a wavelength of 421-414 nm with an increase in band gap energy from 2.94 eV to 2.99 eV, along with a decreased average particle size. The functional groups observed in His-Ag NPs showed wavenumbers at 3320 to 3318 cm-1, 2106 to 2129 cm-1, and 1635 cm-1, showing the OH, CH, and C CO bonds, respectively. The SPR angle of the prism/Au thin film/air structure is 44.80°. Meanwhile, the LSPR angle for the prism/Au thin film/His-Ag NPs/air structure is 44.92°. There is an increase in the LSPR angle by 0.12°. Moreover, the minimum reflectance increases by 0.02. After detecting E. coli bacteria, the LSPR angle shifted by 0.26°, 0.38°, and 0.49° for concentrations of 6.0 × 108 CFU/mL, 6.0 × 107 CFU/mL and 6.0 × 106 CFU/mL respectively. However, the minimum reflectance rose from 0.09° to 0.14°, 0.20°, and 0.22°. Moreover, SPR testing with the structure of the prism/Au thin film/E. coli bacteria/air was carried out to determine the contribution of His-Ag NPs for detecting E. coli bacteria. The results showed that no angular shift occurs. These results indicate that using Ag NPs encapsulated with L-His is essential in amplifying the SPR signal and detecting E. coli bacteria. There was a notable alteration in both the LSPR angle and minimum reflectance indicating that adding His-Ag NPs facilitated the interaction between the E. coli and the sensor surface, thereby enhancing the performance of LSPR-based sensors for E. coli detection for low limit of detection value at 0.47 CFU/mL.

Comparative Metabolomic Profiling of L-Histidine and NEFA Treatments in Bovine Mammary Epithelial Cells

Non-esterified fatty acids (NEFAs) are pivotal in energy metabolism, yet high concentrations can lead to ketosis, a common metabolic disorder in cattle. Our laboratory observed lower levels of L-histidine in cattle suffering from ketosis, indicating a potential interaction between L-histidine and NEFA metabolism. This relationship prompted us to investigate the metabolomic alterations in bovine mammary epithelial cells (BMECs) induced by elevated NEFA levels and to explore L-histidine's potential mitigating effects. Our untargeted metabolomic analysis revealed 893 and 160 metabolite changes in positive and negative models, respectively, with VIP scores greater than 1 and p-values below 0.05. Notable metabolites like 9,10-epoxy-12-octadecenoic acid were upregulated, while 9-Ethylguanine was downregulated. A pathway analysis suggested disruptions in fatty acid and steroid biosynthesis pathways. Furthermore, L-histidine treatment altered 61 metabolites in the positive model and 34 in the negative model, with implications for similar pathways affected by NEFA. Overlaying differential metabolites from both conditions uncovered a potential key mediator, 1-Linoleoylglycerophosphocholine, which was regulated in opposite directions by NEFA and L-histidine. Our study uncovered that both NEFA L- and histidine metabolomics analyses pinpoint similar lipid biosynthesis pathways, with 1-Linoleoylglycerophosphocholine emerging as a potential key metabolite mediating their interaction, a discovery that may offer insights for therapeutic strategies in metabolic diseases.

Effect of carnosine synthesis precursors in the diet on jejunal metabolomic profiling and biochemical compounds in slow-growing Korat chicken

The slow-growing Korat chicken (KR) has been developed to provide an alternative breed for smallholder farmers in Thailand. Carnosine enrichment in the meat can distinguish KR from other chicken breeds. Therefore, our aim was to investigate the effect of enriched carnosine synthesis, obtained by the β-alanine and L-histidine precursor supplementation in the diet, on changes to metabolomic profiles and biochemical compounds in slow-growing KR jejunum tissue. Four hundred 21-day-old female KR chickens were divided into 4 experimental groups: a group with a basal diet, a group with a basal diet supplemented with 1.0% β-alanine, 0.5% L-histidine, and a mix of 1.0% β-alanine and 0.5% L-histidine. The feeding trial lasted 70 d. Ten randomly selected chickens from each group were slaughtered. Metabolic profiles were analyzed using proton nuclear magnetic resonance spectroscopy. In total, 28 metabolites were identified. Significant changes in the concentrations of these metabolites were detected between the groups. Partial least squares discriminant analysis was used to distinguish the metabolites between the experimental groups. Based on the discovered metabolites, 34 potential metabolic pathways showed differentiation between groups, and 8 pathways (with impact values higher than 0.05, P < 0.05, and FDR < 0.05) were affected by metabolite content. In addition, biochemical changes were monitored using synchrotron radiation-based Fourier transform infrared microspectroscopy. Supplementation of β-alanine alone in the diet increased the β-sheets and decreased the α-helix content in the amide I region, and supplementation of L-histidine alone in the diet also increased the β-sheets. Furthermore, the relationship between metabolite contents and biochemical compounds were confirmed using principal component analysis (PCA). Results from the PCA indicated that β-alanine and L-histidine precursor group was highly positively correlated with amide I, amide II, creatine, tyrosine, valine, isoleucine, and aspartate. These findings can help to understand the relationships and patterns between the spectral and metabolic processes related to carnosine synthesis.

Beyond rational-biosensor-guided isolation of 100 independently evolved bacterial strain variants and comparative analysis of their genomes

BACKGROUND

In contrast to modern rational metabolic engineering, classical strain development strongly relies on random mutagenesis and screening for the desired production phenotype. Nowadays, with the availability of biosensor-based FACS screening strategies, these random approaches are coming back into fashion. In this study, we employ this technology in combination with comparative genome analyses to identify novel mutations contributing to product formation in the genome of a Corynebacterium glutamicum L-histidine producer. Since all known genetic targets contributing to L-histidine production have been already rationally engineered in this strain, identification of novel beneficial mutations can be regarded as challenging, as they might not be intuitively linkable to L-histidine biosynthesis.

RESULTS

In order to identify 100 improved strain variants that had each arisen independently, we performed > 600 chemical mutagenesis experiments, > 200 biosensor-based FACS screenings, isolated > 50,000 variants with increased fluorescence, and characterized > 4500 variants with regard to biomass formation and L-histidine production. Based on comparative genome analyses of these 100 variants accumulating 10-80% more L-histidine, we discovered several beneficial mutations. Combination of selected genetic modifications allowed for the construction of a strain variant characterized by a doubled L-histidine titer (29 mM) and product yield (0.13 C-mol C-mol-1) in comparison to the starting variant.

CONCLUSIONS

This study may serve as a blueprint for the identification of novel beneficial mutations in microbial producers in a more systematic manner. This way, also previously unexplored genes or genes with previously unknown contribution to the respective production phenotype can be identified. We believe that this technology has a great potential to push industrial production strains towards maximum performance.

L-histidine inhibits the heat-induced gelation of actomyosin in a low ionic strength solution

The heat-induced gelation of actomyosin plays a key role in meat processing. Our previous study showed that L-histidine could affect the characteristics of a heat-induced gel of myosin on a low ionic strength. To apply the specific effect of L-histidine to meat processing, the heat-induced gel properties of actomyosin in the presence of L-histidine were investigated. Actomyosin in a low ionic strength solution containing L-histidine did not form a gel upon heating. The dynamic rheological properties of actomyosin in low ionic strength solutions were distinct depending on the presence or absence of L-histidine. Electron microscopy showed that, heated at 50°C, actomyosin in a low ionic strength solution containing L-histidine remained a filamentous structure. The surface hydrophobicity of actomyosin was stable up to 50°C in a low ionic strength solution containing L-histidine. In conclusion, L-histidine might suppress the aggregation of actomyosin and inhibit heat-induced gelation in a low ionic strength solution.

Regulation of salt tolerance in the roots of Zea mays by L-histidine through transcriptome analysis

Soil salinization is an important worldwide environmental problem and the main reason to reduce agricultural productivity. Recent findings suggested that histidine is a crucial residue that influences the ROS reduction and improves the plants' tolerance to salt stress. Herein, we conducted experiments to understand the underlying regulatory effects of histidine on maize root system under salt stress (100 mM NaCl solution system). Several antioxidant enzymes were determined. The related expressed genes (DEGs) with its pathways were observed by Transcriptome technologies. The results of the present study confirmed that histidine can ameliorate the adverse effects of salt stress on maize root growth. When the maize roots exposed to 100 mM NaCl were treated with histidine, the accumulation of superoxide anion radicals, hydrogen peroxide, and malondialdehyde, and the content of nitrate nitrogen and ammonium nitrogen were significantly reduced; while the activities of superoxide dismutase, peroxidase, catalase, nitrate reductase, glutamine synthetase, and glutamate synthase were significantly increased. Transcriptome analysis revealed that a total of 454 (65 up-regulated and 389 down-regulated) and 348 (293 up-regulated and 55 down-regulated) DEGs were observed when the roots under salt stress were treated with histidine for 12 h and 24 h, respectively. The pathways analysis of those DEGs showed that a small number of down-regulated genes were enriched in phytohormone signaling and phenylpropanoid biosynthesis at 12 h after histidine treatment, and the DEGs involved in the phytohormone signaling, glycolysis, and nitrogen metabolism were significantly enriched at 24 h after treatment. These results of gene expression and enzyme activities suggested that histidine can improve the salt tolerance of maize roots by enriching some DEGs involved in plant hormone signal transduction, glycolysis, and nitrogen metabolism pathways.

A Convenient and Label-Free Colorimetric Detection for L-Histidine Based on Inhibition of Oxidation of 3,3',5,5'-Tetramethylbenzidine-H2O2 System Triggered by Copper Ions

L-Histidine (L-His) is an essential amino acid, which is used to synthesize proteins and enzymes. The concentration of L-His in the body is controlled to regulate tissue growth and repair of tissues. In this study, a rapid and sensitive method was developed for colorimetric L-his detection using Cu²⁺ ions to inhibit the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB)-H₂O₂ system. H₂O₂ can oxidize TMB to oxTMB in the presence of copper, and the change in color from colorless (TMB) to blue (oxTMB) is similar to that observed in the presence of peroxidase. However, because the imidazole ring and carboxyl group of L-His can coordinate with Cu²⁺ ions to form stable L-His-Cu²⁺ complexes, the color of the TMB-H₂O₂ solution remains unchanged after the addition of L-His. Therefore, because L-His effectively hinders the colorimetric reaction of TMB with H₂O₂, this assay can be used to quantitatively determine the concentration of L-His in samples. Under optimized conditions, our colorimetric sensor exhibited two linear ranges of 60 nM to 1 μM and 1 μM to 1 mM for L-His detection and a detection limit of 50 nM (S/N = 3); furthermore, the assay can be performed within 20 min. Moreover, the proposed assay was used to determine the concentration of L-His in urine samples, suggesting that this convenient and label-free colorimetric method presents promising applications in bioanalytical chemistry and clinical diagnosis.

Single nanoparticle identification coupled with auto-identify algorithm for rapid and accurate detection of L-histidine

In this work, an auto-identify sensor was constructed for rapid and high-precision detection of L-histidine. The proposed strategy is based on the auto-identify algorithm and the aggregation of alkynyl and azide functionalized gold nanoparticles induced by the Cu⁺ catalyzed azides and alkynes cycloaddition (CuAAC) reaction. Specially, the color of scattering light spots for the aggregated gold nanoparticle (AuNPs) caused by CuAAC reaction was quite different from that of the monomers. However, L-histidine can bind to Cu²⁺ and inhibits the production of Cu⁺, hence preventing the aggregation of AuNPs. Therefore, there is a distinct change of color as the addition of L-histidine under dark-field microscopy. Then, L-histidine can be quantitatively detected by combining the color change with the Meanshift algorithm accurately and automatically. Such proposed method has been successfully applied for the detection of L-histidine in serum sample with satisfying result.

Anticancer Potential of L-Histidine-Capped Silver Nanoparticles against Human Cervical Cancer Cells (SiHA)

This study reports the synthesis of silver nanoparticles using amino acid L-histidine as a reducing and capping agent as an eco-friendly approach. Fabricated L-histidine-capped silver nanoparticles (L-HAgNPs) were characterized by spectroscopic and microscopic studies. Spherical shaped L-HAgNPs were synthesized with a particle size of 47.43 ± 19.83 nm and zeta potential of -20.5 ± 0.95 mV. Results of the anticancer potential of L-HAgNPs showed antiproliferative effect against SiHa cells in a dose-dependent manner with an IC₅₀ value of 18.25 ± 0.36 µg/mL. Fluorescent microscopic analysis revealed L-HAgNPs induced reactive oxygen species (ROS) mediated mitochondrial dysfunction, leading to activation of apoptotic pathway and DNA damage eventually causing cell death. To conclude, L-HAgNPs can act as promising candidates for cervical cancer therapy.

Green synthesis of some 3-(α,α-diarylmethyl)indoles by bio-nanocomposite from embedding L-histidinium trichloroacetate ionic liquid on functionalized magnetite (L-His+CCl3CO2-@PEG@SiO2-nano Fe3O4)

In this research, a new multilayered magnetized bio-nanocomposite has been prepared. At first, the amino acid-based ionic liquid was obtained from L-histidine and trichloroacetic acid (L-His⁺CCl₃CO₂^-), embedded on the polyethylene glycol-functionalized silicated-nanomagnetite, to prepare the final nanostructure (L-His⁺CCl₃CO₂^-@PEG@SiO₂-nano Fe₃O₄). The bio-nanocomposite was characterized by several techniques such as FT-IR, FESEM, TGA/DTG, EDAX, TEM, VSM, and XRD. The catalytic activity of the core-shell nanostructure was examined in one-pot three-component reaction between aryl aldehydes, indoles, and β-naphthol/phenols to get some new 3-(α,α-diarylmethyl)indoles under solvent-free conditions at 75 °C. Eco-friendly protocol in the absence of hazardous solvents, no observation of by-products such as bis(indolyl)methanes (BIMs), in addition to recovery and reusability of the nanostructure within 3 runs without activity loss are some highlighted notable features of the work. The reused bio-nanocomposite was also characterized through FESEM technique.

Effects of L-Histidine and Sodium Acetate on β-Casein Expression in Nutrient-Restricted Bovine Mammary Epithelial Cells

Simple Summary

Nutrient restriction is known to decrease the milk production and milk quality of dairy cows. However, providing cows with abundant nutrients also has a disadvantage because it will increase feed costs. Under such a situation, the use of feed additives can be a good strategy to reduce the feed cost. The objective of this study was to investigate the effects of histidine and sodium acetate on β-casein expression in nutrient-restricted bovine mammary epithelial cells. The results indicate that histidine has the potential to increase the β-casein levels in bovine mammary cells when the nutrient is restricted, suggesting that histidine is a potential feed additive for cows in a nutrient-insufficient environment.

Abstract

Nutrient restriction is a challenging condition for the mammary glands of dairy cows. In this condition, supplementing amino acids and energy sources might be a good strategy to improve the concentration of one of the most important caseins in bovine milk. Therefore, the objective of this study was to investigate the effects of L-histidine (His) and sodium acetate (Ace) in a nutrient-restricted (NR) immortalized bovine mammary epithelial cell line (MAC-T cells). The treatments for the MAC-T cells are as follows: experiment (1) 0–5% diluted basal medium; experiment (2) supplementation of 0–9.6 mM of His or Ace in NR or normal conditions; experiment (3) supplementation of 0–9.6 mM of Ace plus 0.15 mM of His in NR or normal conditions. The 1% diluted medium showed no significant effect on the cell viability with the basal medium; thus, it was selected as the NR condition. The relative expression of β-casein was significantly increased in the NR condition with the inclusion of 0.15 mM His alone or with Ace compared to that in control. The supplementation of Ace increased the β-casein level under normal conditions. However, it did not change the expression of β-casein under the NR condition. The results suggest that His has the potential to increase the β-casein expression under the NR condition.

Effects of beta-alanine supplementation on Yo-Yo test performance: A meta-analysis

OBJECTIVE

The aim of this meta-analysis was to explore the effects of beta-alanine supplementation on Yo-Yo test performance.

METHODS

Nine databases were searched to find relevant studies. A random-effects meta-analysis of standardized mean differences (SMD) was performed for data analysis. Subgroup meta-analyses were conducted to explore the effects of beta-alanine supplementation duration on Yo-Yo test performance, and the effects of beta-alanine supplementation on performance only in Yo-Yo level 2 test variants.

RESULTS

Ten study groups were included in the meta-analysis. All studies included athletes as study participants. When considering all available studies, there was no significant difference between the placebo/control and beta-alanine groups (SMD: 0.68; 95% confidence interval [CI]: -0.30, 1.67). When considering only the studies that used supplementation protocols lasting between 6 and 12 weeks, there was a significant ergogenic effect of beta-alanine (SMD: 1.02; 95% CI: 0.01, 2.05). When considering only the studies that used the level 2 variants of the Yo-Yo test, there was a significant ergogenic effect of beta-alanine (SMD: 1.41; 95% CI: 0.35, 2.48).

CONCLUSIONS

This meta-analysis found that beta-alanine is ergogenic for Yo-Yo test performance in athletes when the supplementation protocol lasts between 6 and 12 weeks and when using the level 2 variants of the Yo-Yo test.

Effect of Biochar on the Production of L-Histidine From Glucose Through Escherichia coli Metabolism

The organic compounds from biochar play a role of hormone analogs, stimulating the expression of metabolites by controlling related gene and protein. In this experiment, we reported the L-histidine biosysthesis was promoted by biochar treatment in E. coli unlike genetic engineering of the traditional method. The related results indicated the most optimal concentration was found to be 3%, and 7% is the lethal dose. E. coli was inhibited in the high-concentration treatment. On the other hand, docking technology was usually used as drug screening, basing on Lock-and-key model of protein in order to better understand mechanisms. So the organic compounds of biochar from GC-MS analysis that acted as ligands were connected to HisG protein controlling L-histidine biosysthesis in E. coli. The result showed that the three organic molecules interacted with HisG protein by hydrogen bond. So we considered that these three compounds play regulatory roles in L-histidine biosysthesis, and the hisG gene expression fully supports this conclusion.

Case Report: Infusion-Related Reactions to Intravenous Infliximab and Subcutaneous Ustekinumab in Pediatric Crohn's Disease

Background: Although the biological agent ustekinumab (UST) is reported to be effective for Crohn's disease (CD) in pediatric as well as adult patients, data on the efficacy and safety of UST in pediatric patients with CD are limited. Here, we describe the case of a pediatric patient who showed an allergic reaction to UST after subcutaneous (SC) maintenance injections but not immediately after initial intravenous (IV) injection. Case Presentation: A 9-year-old boy presented to our hospital with diarrhea lasting 2 years and weight loss, leading to the diagnosis of CD. After prednisolone (PSL) was tapered and discontinued, he promptly relapsed. According to our institution's protocol, we introduced the biological agent infliximab (IFX) with premedication. Coughing and vomiting was observed after the second dose of IFX and it was changed to adalimumab (ADA). However, the effect of ADA gradually disappeared after 18 months; therefore, it was discontinued and he was treated using UST. The first IV UST dose was given after administering hydrocortisone (HDC), an antiallergic and antipyretic analgesic, as premedication, and no obvious adverse reaction was observed. After 8 weeks, UST was subcutaneously injected without premedication. The patient then complained of nausea, dizziness, and headache within 15 min of UST administration. Therefore, for the third dose of UST, HDC was administered again as premedication. However, nausea, dizziness, and headache presented 10 min after UST administration, resulting in discontinuation of further UST treatment. Conclusion: Careful distinction between "true" infusion-related reactions (IRRs) and anaphylaxis or allergic reactions is necessary to determine whether biological agents can be continued after the development of "so-called" IRRs. For true IRRs, it may be possible to continue using the biological agent with appropriate premedication; however, in cases of anaphylaxis, the biological agent itself should be changed.

Agonism of Histaminergic-H1 Receptors in Ischemic Postconditioning During Cerebral Ischemia-Reperfusion Injury is Protective

BACKGROUND

Stroke is associated with cerebral ischemia/reperfusion (I/R) injury. Ischemic postconditioning (IPoC) reduces cerebral ischemic injury in rats and offers neuroprotection. The central histaminergic pathway possesses a crucial role in the pathogenesis of cerebral I/R, but its neuroprotective role in IPoC is still unidentified.

OBJECTIVE

This research explored the role of the histaminergic in IPoC during cerebral I/R injury in the rat.

METHODS

Global cerebral ischemia/reperfusion (GCI/R) injury in Wistar albino rats was induced by occluding the bilateral carotid arteries for 10 minutes, followed by reperfusion. IPoC was provided by giving three episodes of I/R post GCI (10 min), after which of reperfusion was permitted. Inclined- beam-walk, hanging-wire, lateral-push, and rota-rod tests were employed to assess motor functions, and Morris water maze (MWM) was used to assess spatial learning as well as memory in animals. Cerebral oxidative markers (thiobarbituric acid reactive species-TBARS, reduced glutathione- GSH), inflammatory markers (myeloperoxidase-MPO), acetylcholinesterase activity- AChE, infarct size, and histopathological changes were also assessed. L-histidine and chlorpheniramine were used as histaminergic agonists and antagonists.

RESULTS

I/R animals showed a reduction in memory and motor function, and an increase in cerebral oxidative stress, inflammation, AChE activity, infarct size and histopathological changes. Episodes of IPoC post-ischemia attenuated the deleterious effects of I/R injury. Pretreatment (30 min before cerebral ischemia) with L-histidine mimicked the neuroprotective effects of IPoC. However, neuroprotection produced by IPoC was abolished by pretreatment with chlorpheniramine (histaminergic- H₁ receptor antagonist).

CONCLUSION

IPoC may provide neuroprotection against cerebral I/R induced brain injury by modulating the histaminergic-H1-receptor pathway.

L-histidine controls the hydroxyapatite mineralization with plate-like morphology: Effect of concentration and media

Hydroxyapatite (HA) is the main inorganic component of bone and dentin, and their non-stoichiometric compositions and plate-shaped morphology is responsible for their bioactivity and osteoconductive nature. Collagenous (CPs) and non-collagenous proteins (NCPs) facilitate mineralization and regulate structural properties of HA through their side-chains. The bioactivity of synthetic HA does not usually match with the HA found in bone and, therefore, there is a need to understand the role of biomolecules in bone mineralization in order to develop non-stoichiometric plate-shaped HA for bone grafts. Role of several amino acids has been investigated but the role of L-his has been rarely investigated under physiological conditions even though it is a part of HA inhibitor proteins, like albumin, amelogenin, and histidine-rich proteins. In this study, L-his and L-glu were used to modify the structural properties of HA in different experimental conditions and buffer systems (tris and hepes). The results showed that L-his was able to regulate the plate-shaped morphology of HA in every experimental condition, unlike the L-glu, where the crystal morphology was regulated by experimental conditions. Both amino acids behaved differently in DI water, tris, and hepes buffer, and the media used influenced the precipitation time and structural properties of HA. Hepes and tris buffers also influenced the HA precipitation process. Overall, the studies revealed that L-his may be used as an effective regulator of plate-shaped morphology of HA, instead of large NCPs/proteins, for designing biomaterials for bone regeneration applications and the choice of buffer system is important in designing and evaluating the systems for mineralization. In cell culture studies, mouse osteoblast precursor cells (MC3T3-E1) showed highest proliferation on the bone-like plate-shaped HA, among all the HA samples investigated.

Poly-L-histidine coated microfluidic devices for bacterial DNA purification without chaotropic solutions

We present a disposable polymeric microfluidic device capable of reversibly binding and purifying Salmonella DNA through solid phase extraction (SPE). The microfluidic channels are first oxygen plasma treated and simultaneously micro-nanotextured, and then functionalized with amine groups via modification with L-histidine or poly-L-histidine. L-Histidine and poly-L-histidine bind on the plasma treated chip surface, and are not detached when rinsing with DNA purification protocol buffers. A pH-dependent protocol is applied on-chip to purify Salmonella DNA, which is first bound on the protonated amines at a pH (5.0) lower than their pKa of surface amine-groups which is 6.0 and then released at a pH higher than the pKa value (10.5). It was found that modification with poly-L-histidine resulted in higher surface density of amine groups onto microfluidic channel. Using the chip modified with poly-L-histidine, high recovery efficiency of at least 550 ng of isolated Salmonella DNA as well as DNA purification from Salmonella cell lysates corresponding to less than 5000 cells or 0.026 ng of Salmonella DNA was achieved. The protocol developed does not require ethanol or chaotropic solutions typically used in DNA purification, which are known inhibitors for downstream operations such as polymerase chain reactions (PCR) and which can also attack some polymeric microfluidic materials. Therefore, the microfluidic device and the related protocol hold promise for facile incorporation in microfluidics and Lab-on-a-chip (LOC) platforms for pathogen detection or in general for DNA purification.

[Elucidation of New Function in Endothelial Cells for Efficient Delivery Strategy of Drug to Tissues]

The author has described two new functions of endothelial cells for efficient delivery of drugs to tissues. First, it was indicated that tight junction (TJ)-associated protein, claudin-1, exerts potent paracellular barrier function in cultured mouse lung microvascular endothelial cells (LMECs). This barrier was instantly and reversibly opened by reduction of TJ proteins expression via histamine H₁ and H₂ receptors. Histamine was biosynthesized by l-histidine decarboxylase from uptaken l-histidine, and biotransformed by type B of monoamine oxidase, suggesting that histamine concentration is controlled in rat brain MECs (BMECs) and LMECs. Moreover, uptake of l-histidine into BMECs and LMECs markedly increased with addition of ZnSO₄. Second, it was suggested that drug-metabolizing enzymes such as CYP and flavin-containing monooxygenase exist in vascular endothelial cells exposed to blood and to aerobic conditions. These cells have the same ability to metabolize drugs as hepatocytes, demonstrating that vascular endothelial cells are a metabolic barrier against tissue transfer of drugs. From these results, it was suggested that reversible opening of TJ and selective inhibition of drug metabolism in vascular endothelial cells may be efficient delivery strategies of drugs to tissues. Finally, I hope that this research will lead to development of new drugs and possible re-evaluation of discontinued drugs.

Application of Mn-Cu Helical Star-Shaped (Pine-Tree-Like) Sculpted Thin Films with Different Symmetries Using Surface-Enhanced Raman Spectroscopy (SERS)

In this work, the surface engineering method is used to produce Mn helical star-shaped (pine-tree-like) nanosculptured thin films with three-, four-, and fivefold symmetries on Cu substrates using an oblique angle deposition technique together with rotation of the sample holder at certain angles. Nano structure and morphologies of the produced samples were obtained by means of atomic force microscope and field emission scanning electron microscope. Raman spectroscopy of the Mn/Cu samples impregnated by 4,4'-bipyridine (C₁₀H₈N₂) solution with different concentrations, zidovudine (C₁₀H₁₃N₅O₄), and L-histidine (C₆H₉N₃O₂) was performed using 532 nm laser wavelength. A high degree of enhancement is achieved on Raman spectroscopy of all of these specimens. Comparison of the surface-enhanced Raman spectroscopy (SERS) results for 4,4' bipyridine (bipy) obtained in this work with the published literature using Ag and Au substrates in different shapes showed a significant enhancement improvement by using Mn sculptured structures. Reduction of the bipy concentration changed the enhancement factor. Enhancement factors of 10⁷ and 10⁵ were obtained for threefold symmetry sample using 2.885 × 10^-2 and 10^-3mol L^-1 bipy concentrations, respectively. Surface-enhanced Raman spectroscopy results of this work show that Mn nanostructures designed and engineered in this work can not only replace Ag and Au materials, but also provide a much higher enhancement factor.

The Potential of Carnosine in Brain-Related Disorders: A Comprehensive Review of Current Evidence

Neurological, neurodegenerative, and psychiatric disorders represent a serious burden because of their increasing prevalence, risk of disability, and the lack of effective causal/disease-modifying treatments. There is a growing body of evidence indicating potentially favourable effects of carnosine, which is an over-the-counter food supplement, in peripheral tissues. Although most studies to date have focused on the role of carnosine in metabolic and cardiovascular disorders, the physiological presence of this di-peptide and its analogues in the brain together with their ability to cross the blood-brain barrier as well as evidence from in vitro, animal, and human studies suggest carnosine as a promising therapeutic target in brain disorders. In this review, we aim to provide a comprehensive overview of the role of carnosine in neurological, neurodevelopmental, neurodegenerative, and psychiatric disorders, summarizing current evidence from cell, animal, and human cross-sectional, longitudinal studies, and randomized controlled trials.

Effect of Amino Acids on Growth Performance, Carcass Characteristics, Meat Quality, and Carnosine Concentration in Broiler Chickens

The aim of this research was to investigate the deposition of carnosine in broiler muscles by feeding treatments comprising β-alanine, L-histidine, and magnesium oxide in various concentrations. The research was carried out on 120 Cobb 500 broilers divided into four groups. From weeks four to six, broilers were fed finisher mixtures as follows: P1, control group; P2, 0.5% β-alanine + 0.24% MgO; P3, 0.25% L-histidine + 0.24% MgO; and P4, 0.20% β-alanine + 0.10% L-histidine + 0.24% MgO. This paper presents the weights of broilers and their carcasses, portions of main parts of carcasses, technological quality of breast muscles, and concentrations of carnosine in breast and thigh muscles. The following traits of muscle tissue quality were measured: initial and final pH value (45 min after slaughtering pH₁, and 24 h after cooling pH₂), drip loss, color (Minolta colorimeter, expressed as CIE L*, CIE a*, and CIE b* values), meat softness, and cooking loss. Data on relative concentration of protein carbonyl (nmol/mg protein) in the muscles of breasts and thighs and levels of thiobarbituric acid-reactive substances (TBARS) in fresh and frozen breasts muscles (nmol/mg of tissue) are presented. Statistical analysis proved that feeding treatments had an effect on the live weight of broilers in the 4th, 5th, and 6th weeks of fattening (P<0.05), as well as on the carcass quality at slaughter (P<0.05; except the portion of wings), pH₁ value (P=0.035), CIE a* indicator (P=0.007), drip loss (P=0.002), and meat texture (P=0.008). Compared to the control group, synthesis and deposition of carnosine were increased in breast muscles in groups P2, P3, and P4 by 7.51%, 10.62%, and 62.93%, respectively, and in thigh muscles by 61.05%, 78.95%, and 89.52%, respectively. It was also confirmed that feeding treatments influenced the level of TBARS in frozen broiler breast muscles (P=0.014).

Semi-Mechanistic Population Pharmacokinetic Modeling of L-Histidine Disposition and Brain Uptake in Wildtype and Pht1 Null Mice

PURPOSE

To develop a semi-mechanistic population pharmacokinetic (PK) model to quantitate the disposition kinetics of L-histidine, a peptide-histidine transporter 1 (PHT1) substrate, in the plasma, cerebrospinal fluid and brain parenchyma of wildtype (WT) and Pht1 knockout (KO) mice.

METHODS

L-[¹⁴C]Hisidine (L-His) was administrated to WT and KO mice via tail vein injection, after which plasma, cerebrospinal fluid (CSF) and brain parenchyma samples were collected. A PK model was developed using non-linear mixed effects modeling (NONMEM). The disposition of L-His between the plasma, brain, and CSF was described by a combination of PHT1-mediated uptake, CSF bulk flow and first-order micro-rate constants.

RESULTS

The PK profile of L-His was best described by a four-compartment model. A more rapid uptake of L-His in brain parenchyma was observed in WT mice due to PHT1-mediated uptake, a process characterized by a Michaelis-Menten component (V_max = 0.051 nmoL/min and K_m = 34.94 μM).

CONCLUSIONS

A semi-mechanistic population PK model was successfully developed, for the first time, to quantitatively characterize the disposition kinetics of L-His in brain under in vivo conditions. This model may prove a useful tool in predicting the uptake of L-His, and possibly other PHT1 peptide/mimetic substrates, for drug delivery to the brain.

Effects of intraperitoneally administered L-histidine on food intake, taste, and visceral sensation in rats

To evaluate relative factors for anorectic effects of L-histidine, we performed behavioral experiments for measuring food and fluid intake, conditioned taste aversion (CTA), taste disturbance, and c-Fos immunoreactive (Fos-ir) cells before and after i.p. injection with L-histidine in rats. Animals were injected with saline (9 ml/kg, i.p.) for a control group, and saline (9 ml/kg, i.p.) containing L-histidine (0.75, 1.5, 2.0 g/kg) for a L-histidine group. Injection of L-histidine decreased the average value of food intake, and statistically significant anorectic effects were found in animals injected with 1.5 or 2.0 g/kg L-histidine but not with 0.75 g/kg L-histidine. Taste abnormalities were not detected in any of the groups. Animals injected with 2.0 g/kg L-histidine were revealed to present with nausea by the measurement of CTA. In this group, a significant increase in the number of Fos-ir cells was detected both in the area postrema and the nucleus tractus solitarius (NTS). In the 0.75 g/kg L-histidine group, a significant increase in the number of Fos-ir cells was detected only in the NTS. When the ventral gastric branch vagotomy was performed, recovery from anorexia became faster than the sham-operated group, however, vagotomized rats injected with 2.0 g/kg L-histidine still acquired CTA. These data indicate that acute anorectic effects induced by highly concentrated L-histidine are partly caused by induction of nausea and/or visceral discomfort accompanied by neuronal activities in the NTS and the area postrema. We suggest that acute and potent effects of L-histidine on food intake require substantial amount of L-histidine in the diet.

Enantioselective surface plasmon resonance sensor based on C60 fullerene-glutathione self-assembled monolayer (SAM)

A novel enantioselective surface plasmon resonance (SPR) sensor based on a self-assembled monolayer of C60 fullerene as the chiral selector is proposed. A binding assay, apparent affinity constant, and apparent dissociation binding constant were used to analyze and study the enantioselectivity of C60 fullerene-glutathione film for L-histidine, which was chosen as the model analyte. The apparent affinity constant for the complex formed by L-histidine with C60 fullerene-glutathione film was 5.2 x 10(9)  M(-1). The proposed SPR sensor can be used for the assay of L-histidine in the 10(-10)-10(-7)  mol/L concentration range.