Diamine Oxidase-Conjugated Multiwalled Carbon Nanotubes to Facilitate Electrode Surface Homogeneity

Carbon nanomaterials have gained significant interest over recent years in the field of electrochemistry, and they may be limited in their use due to issues with their difficulty in dispersion. Enzymes are prime components for detecting biological molecules and enabling electrochemical interactions, but they may also enhance multiwalled carbon nanotube (MWCNT) dispersion. This study evaluated a MWCNT and diamine oxidase enzyme (DAO)-functionalised screen-printed electrode (SPE) to demonstrate improved methods of MWCNT functionalisation and dispersion. MWCNT morphology and dispersion was determined using UV-Vis spectroscopy (UV-Vis) and scanning electron microscopy (SEM). Carboxyl groups were introduced onto the MWCNT surfaces using acid etching. MWCNT functionalisation was carried out using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS), followed by DAO conjugation and glutaraldehyde (GA) crosslinking. Modified C-MWNCT/EDC-NHS/DAO/GA was drop cast onto SPEs. Modified and unmodified electrodes after MWCNT functionalisation were characterised using optical profilometry (roughness), water contact angle measurements (wettability), Raman spectroscopy and energy dispersive X-ray spectroscopy (EDX) (vibrational modes and elemental composition, respectively). The results demonstrated that the addition of the DAO improved MWCNT homogenous dispersion and the solution demonstrated enhanced stability which remained over two days. Drop casting of C-MWCNT/EDC-NHS/DAO/GA onto carbon screen-printed electrodes increased the surface roughness and wettability. UV-Vis, SEM, Raman and EDX analysis determined the presence of carboxylated MWCNT variants from their non-carboxylated counterparts. Electrochemical analysis demonstrated an efficient electron transfer rate process and a diffusion-controlled redox process. The modification of such electrodes may be utilised for the development of biosensors which could be utilised to support a range of healthcare related fields.

Polyamine Oxidation Is Indispensable for Wheat (Triticum aestivum L.) Oxidative Response and Necrotic Reactions during Leaf Rust (Puccinia triticina Eriks.) Infection

Hydrogen peroxide is a signal and effector molecule in the plant response to pathogen infection. Wheat resistance to Puccinia triticina Eriks. is associated with necrosis triggered by oxidative burst. We investigated which enzyme system dominated in host oxidative reaction to P. triticina infection. The susceptible Thatcher cultivar and isogenic lines with defined resistance genes were inoculated with P. triticina spores. Using diamine oxidase (DAO) and polyamine oxidase (PAO) inhibitors, accumulation of H2O2 was analyzed in the infection sites. Both enzymes participated in the oxidative burst during compatible and incompatible interactions. Accumulation of H2O2 in guard cells, i.e., the first phase of the response, depended on DAO and the role of PAO was negligible. During the second phase, the patterns of H2O2 accumulation in the infection sites were more complex. Accumulation of H2O2 during compatible interaction (Thatcher and TcLr34 line) moderately depended on DAO and the reaction of TcLr34 was stronger than that of Thatcher. Accumulation of H2O2 during incompatible interaction of moderately resistant plants (TcLr24, TcLr25 and TcLr29) was DAO-dependent in TcLr29, while the changes in the remaining lines were not statistically significant. A strong oxidative burst in resistant plants (TcLr9, TcLr19, TcLr26) was associated with both enzymes’ activities in TcLr9 and only with DAO in TcLr19 and TcLr26. The results are discussed in relation to other host oxidative systems, necrosis, and resistance level.

Association of Serum Copper Levels and Amine Oxidase Copper Gene 1 (AOC1) with Migraineurs

Migraine is a common neurovascular multifactorial disease with biochemical abnormalities in the central nervous system (CNS). It is characterized by episodes of frequent headaches, affecting about 14% of the world's population. Trace elements are essential to play an important role in neurotransmission and causing oxidative stress in patients with migraine. Also, it is hypothesized that Histamine (biogenic amine), catabolized by Diamine oxidase (DAO), induces a vascular headache. DAO contains Copper as a cofactor and is coded by the Amine oxidase copper containing 1 (AOC1) gene. This study aims to determine the level of serum copper (Cu), an association of the AOC1 gene and antioxidant capacity in migraine patients. In this study, a total number of 200 individuals (patients and controls) were equally distributed in each group according to demographic details obtained. The results obtained from this study were found to be significant to migraine. The frequency of T allele (rs10156191) in exon 4 AOC1 was 7.5% in migraineurs OR of 16.13; 95% CI- 0.63 to 47.97, and the p-value was observed to be 0.074. The mean concentration of Cu was found to be 0.09 ± 0.02 mg/L and 0.22 ± 0.10 mg/L in patients and controls, respectively. Antioxidant capacity of serum was found to be lower in patients (3 ± 1.2 μM ascorbic acid equivalents) when compared to controls (7 ± 0.9 μM ascorbic acid equivalents). Decreased Cu and a nonsynonymous of rs10156191 are associated with migraine, which may decrease in DAO activity. Further research, needs to be focused on the DAO activity that can determine the migraine-inducing effect.

The gut-liver axis in nonalcoholic fatty liver disease: association of intestinal permeability with disease severity and treatment outcomes

Objective To investigate the association between intestinal permeability and severity of nonalcoholic fatty liver disease (NAFLD), and the value of intestinal permeability in predicting the efficacy of metabolic therapy for NAFLD. Methods Disease severity was compared between patients with normal and elevated intestinal permeability; correlations between D-lactate and different NAFLD parameters were analyzed; and the effects of metabolic therapy on NAFLD patients with normal and elevated intestinal permeability were evaluated. Results A total of 190 patients with NAFLD were enrolled. NAFLD patients with elevated intestinal permeability had significantly higher levels of liver test parameters, liver ultrasonographic fat attenuation parameter, triglyceride, homeostasis model assessment of insulin resistance value and diamine oxidase (all P˂0.05) than NAFLD patients with normal intestinal permeability. Further, serum D-lactate levels were positively correlated with alanine transaminase, aspartate transaminase, gamma-glutamyl transpeptidase, total bilirubin, indirect bilirubin, fat attenuation parameter, triglyceride, and diamine oxidase (all P˂0.05). Moreover, NAFLD patients with elevated intestinal permeability showed less improvement in TG levels (P=0.014) after metabolic therapy. Conclusion Intestinal permeability correlates with the disease severity in patients with NAFLD. Moreover, intestinal permeability may have value for predicting the efficacy of metabolic therapy for NAFLD patients.

Effects of feed with different protein digestion kinetic profiles on intestinal health of growing pigs

This study evaluated the effects of feed ingredients with different protein digestion kinetic profiles on the intestinal health of growing pigs. Two protein sources were selected, namely casein (CAS) as a rapid release source of amino acids (AAs), and corn gluten meal (CGM) as a slow-release source. Twenty-four crossbred barrows (Duroc × Landrace × Yorkshire) with similar bodyweight (43.27 ± 3.51 kg) were selected and randomly assigned to four treatments with six barrows. These consisted of T1: 13.2% digestible crude protein (CP) with supplemental CAS; T2: 13.2% digestible CP with supplemental CGM; T3: 11.2% digestible CP with supplemental CAS (T3); and T4: 11.2% digestible CP with supplemental CGM. Diets with CGM had increased crypt depth in the duodenum, jejunum, and ileum and reduced villi height in the jejunum in comparison with CAS. They also had increased intestinal permeability, as seen by the high level of serum diamine oxidase (DAO) compared with CAS. The diets with CAS increased health-promoting Lactobacillus and decreased health-threatening Treponema compared with those fed CGM diets. The CAS diets had a positive effect on gut functions with increased villi height, decreased crypt depth and high villi height/crypt depth. Thus, use of CAS in diets for pigs is favoured over CGM.

Ageratina adenophora Disrupts the Intestinal Structure and Immune Barrier Integrity in Rats

The aim of this study was to investigate the effects of Ageratina adenophora on the intestines morphology and integrity in rat. Rats were randomly divided into two groups and were fed with 10 g/100 g body weight (BW) basal diet and 10 g/100 g BW experimental diet, which was a mixture of A. adenophora powder and basal diet in a 3:7 ratio. The feeding experiment lasted for 60 days. At days 28 and 60 of the experiment, eight rats/group/timepoint were randomly selected, weighed, and sacrificed, then blood and intestinal tissues were collected and stored for further analysis. The results showed that Ageratina adenophora caused pathological changes and injury in the intestine, elevated serum diamine oxidase (DAO), D-lactate (D-LA), and secretory immunoglobulin A (sIgA) levels, reduced occludin levels in intestinal tissues, as well as increased the count of intraepithelial leukocytes (IELs) and lamina propria leukocytes (LPLs) in the intestine (p < 0.05 or p < 0.01). In addition, the mRNA and protein (ELISA) expressions of pro-inflammation cytokines (IL-1β, IL-2, TNF-α, and IFN-ϒ) were elevated in the Ageratina adenophora treatment groups, whereas anti-inflammatory cytokines such as IL-4 and IL-10 were reduced (p < 0.01 or p < 0.05). Therefore, the results obtained in this study indicated that Ageratina adenophora impaired intestinal function in rats by damaging the intestine structure and integrity, and also triggered an inflammation immune response that led to intestinal immune barrier dysfunction.

Heparin-binding motif mutations of human diamine oxidase allow the development of a first-in-class histamine-degrading biopharmaceutical

<strong>Background:</strong> Excessive plasma histamine concentrations cause symptoms in mast cell activation syndrome, mastocytosis or anaphylaxis. Anti-histamines are often insufficiently efficacious. Human diamine oxidase (hDAO) can rapidly degrade histamine and therefore represents a promising new treatment strategy for conditions with pathological histamine concentrations. <strong>Results:</strong> Recombinant hDAO is rapidly cleared from the circulation in rats and mice. After replacement of positively charged amino acids of the heparin-binding motif with polar serine or threonine residues binding to heparin and heparan sulfate was strongly reduced. The double mutant rhDAO-R568S/R571T showed minimal cellular uptake. The short α-distribution half-life of the wildtype protein was eliminated and the clearance was significantly reduced in rodents. <strong>Conclusions: </strong>The successful decrease in plasma clearance of rhDAO by mutations of the heparin-binding motif with unchanged histamine-degrading activity represents the first step towards the development of rhDAO as a first-in-class biopharmaceutical to effectively treat diseases characterized by excessive histamine concentrations in plasma and tissues. <strong>Funding: </strong>Austrian Science Fund (FWF) Hertha Firnberg program grant T1135 (EG); ADD funding Sigrid Juselius Foundation, Medicinska Understödsförening Liv och Hälsa rft (TAS and SeV).

Histamine Intolerance in Children: A Narrative Review

Histamine intolerance is defined as a disequilibrium of accumulated histamine and the capacity for histamine degradation. This clinical term addresses a non-immunologically mediated pathology when histamine ingested with food is not particularly high, however its degradation is decreased. This paper aims to provide a narrative review on etiopathology, epidemiology, possible diagnostic algorithms and diagnostic challenges of histamine intolerance in children. The clinical picture of histamine intolerance in children is similar to that observed in adults apart from male predominance found in paediatric patients. Both in children and adults, a histamine-reduced diet is typically the treatment of choice. Diamine oxidase supplementation offers another treatment option. There is no symptom or test pathognomonic for histamine intolerance. Nevertheless, manifestations of chronic gastrointestinal symptoms, measurements of diamine oxidase deficits, positive results of histamine provocation tests and improvement in symptoms with histamine-reduced diet considerably increase the probability of histamine intolerance diagnosis. These factors have been included in the proposed diagnostic algorithm for histamine intolerance. In children histamine intolerance most likely co-occurs with allergies and bowel diseases, which creates an additional diagnostic challenge. As the evidence for children is poor further research is needed the determine epidemiology, validate diagnostic algorithms and establish possible treatment options regarding histamine intolerance.