Serum Diamine Oxidase Concentrations Research Articles

Measurement of diamine oxidase (DAO) during low-histamine or ordinary diet in patients with histamine intolerance

Background/ObjectivesQuantification of diamine oxidase (DAO) concentrations in serum has been proposed as an adjunctive diagnostic modality for the evaluation of histamine intolerance (HIT). Limited empirical data exist concerning the influence of dietary patterns on DAO levels.Subjects/MethodsIn the context of a prospective study employing a crossover design, 18 individuals diagnosed with HIT were randomized to initiate either a low histamine diet (LHD) or a conventional mixed diet (MXD). Serum DAO concentrations were measured at the commencement of the study and following each dietary phase. A control group underwent analogous DAO assessments without imposition of dietary constraints.ResultsDuring the time when a diet restricted in histamine was implemented, noticeable differences in changes in DAO levels did not become apparent when compared to the changes observed during the mixed (MXD) phase. Specifically, among the group, 10 of the 18 patients exhibited elevated DAO values subsequent to the LHD regimen, while the remaining eight displayed either reduced or unchanging DAO levels. The prevalence of elevated DAO levels in the LHD group did not differ significantly from that observed in the control group during the MXD phase. Additionally, during the LHD phase, patients reported a significant reduction in gastrointestinal and cutaneous symptoms.ConclusionsThis prospective investigation underscores the enduring utility of a histamine-restricted diet, coupled with structured dietary reintroduction, as an efficacious diagnostic approach for individuals presenting with suspected food-related histamine hypersensitivity. Notably, the measurement of DAO levels appears to furnish only a limited capacity to discern dietary-induced fluctuations. Notwithstanding, the dynamics of DAO alteration do not appear to exhibit a discernible association with specific dietary patterns, a finding consistent across both patient and control groups.

Maternal Magnolol Supplementation during Pregnancy and Lactation Promotes Antioxidant Capacity, Improves Gut Health, and Alters Gut Microbiota and Metabolites of Weanling Piglets.

Maternal nutrition exerts a profound effect on the postnatal performance of offspring, especially during the weaning period. The multifunctional bioactive component magnolol (MAG) has shown promise as a dietary supplement. This study aimed to explore the effects of maternal MAG supplementation on the antioxidant capacity, gut health, gut microbiome, and metabolome composition of weanling piglets. Fifty pregnant sows were randomly divided into two equally sized groups, the control group and the group supplemented with 100 g/t MAG during the gestation and lactation periods, and 7 days postweaning, the pups were euthanized. The microbiome and metabolome features of weanling piglet colons were compared. Our results revealed that maternal MAG supplementation modified the serum redox status of weanling piglets by decreasing malondialdehyde concentration and increasing superoxide dismutase activity and total antioxidant capacity. Moreover, the decreased indicators of diarrhea were accompanied by improved gut barrier function, in which serum diamine oxidase concentration was decreased, and expressions of zona occludens-1, claudin-1, and intestinal alkaline phosphatase were increased in the colon of weanling piglets from sows supplemented with MAG. Further analysis of the gut microbiota indicated that maternal MAG supplementation significantly increased the relative abundance of beneficial bacteria in the colon of weanling piglets, including Faecalibacterium prausnitzii and Oscillospira. Metabolome analysis identified 540 differential metabolites in the colon of piglets from MAG-fed dams, of which glycerophospholipid classes were highly correlated with progeny gut health and key beneficial bacteria. Our findings indicated that maternal MAG supplementation can improve the oxidative status and gut health of weanling piglets, possibly due to alterations in the gut microbiota and metabolites.

Changes in serum concentration and activity of diamine oxidase during the first month of life in calves.

The serum concentration and activity of diamine oxidase (DAO) in calves with or without diarrhea during the first month of life were examined. The serum DAO concentration was highest on day 0 after birth, and gradually decreased. No differences in serum DAO concentrations were observed between calves with diarrhea and control calves. In contrast, serum DAO activity was lowest on day 0 after birth, and gradually increased. Serum DAO activity in calves with diarrhea was lower than that in the control calves from day 20 after birth. These findings suggest that serum DAO activity and concentration are not correlated, and serum DAO activity is useful for assessing damage to the small intestinal mucosa in calves.

Sepsis induces variation of intestinal barrier function in different phase through nuclear factor kappa B signaling.

The intestinal barrier function disrupted in sepsis, while little is known about the variation in different phases of sepsis. In this study, mouse models of sepsis were established by caecal ligation and puncture (CLP). The H&E staining of sections and serum diamine oxidase concentration were evaluated at different timepoint after CLP. TUNEL assay and EdU staining were performed to evaluate the apoptosis and proliferation of intestinal epithelium. Relative protein expression was assessed by Western blotting and serum concentrations of pro-inflammatory cytokines was measured by ELISA. The disruption of intestinal barrier worsened in the first 24 h after the onset of sepsis and gradually recovered over the next 24 h. The percentage of apoptotic cell increased in the first 24 h and dropped at 48 h, accompanied with the proliferative rate of intestinal epithelium inhibited in the first 6 h and regained in the later period. Furthermore, the activity of nuclear factor kappa B (NF-κB) presented similar trend with the intestinal barrier function, shared positive correction with apoptosis of intestinal epithelium. These findings reveal the conversion process of intestinal barrier function in sepsis and this process is closely correlated with the activity of NF-κB signaling.

Standardization of a colorimetric technique for determination of enzymatic activity of diamine oxidase (DAO) and its application in patients with clinical diagnosis of histamine intolerance

BackgroundDiamine Oxidase (DAO) has an essential role for degradation of exogenous histamine in the intestine; thus, histamine intolerance (HI) mainly has been correlated to a low concentration and/or activity of this enzyme. The objective of the study was to standardize a colorimetric technique to measure the enzymatic activity (function) of hDAO to then apply it to a series of 22 patients with a clinical diagnosis of HI. MethodsFor the standardization variables such as volume and type of sample, incubation time, wavelength of maximum absorption, types of substrates, and concentration of oxidized ascorbate were evaluated. Then the activity and concentration of DAO was determined in 22 patients diagnosed with HI and 22 healthy subjects. ResultsThe mean of serum DAO concentration in the 22 patients was of 9.268 ± 1.124 U/mL. The mean of serum DAO concentration in the 22 controls was of 20.710 ± 2.509 U/mL, being significantly higher (P value 0.0002) the mean of the samples. The mean of serum DAO activity of the patients was of 1.143 ± 0.085 U/L and the controls was 1.533 ± 0.119 U/L, significantly greater than the patients (P value 0.011). In addition, the sensitivity of both techniques was 0.63. In the measuring of DAO concentration the specificity was 0.9, constituting a good diagnostic test, especially to rule out the true negatives. The determination of DAO activity had a specificity of 0.68. ConclusionsAlthough we used a small number of patients and controls and the absorbance values were lower than expected, statistically significant differences were found in the levels of concentration and DAO activity between the patients with histamine intolerance and the controls. Therefore, the measuring of DAO concentration and DAO activity is a good diagnostic strategy for study suspect cases of HI. The simultaneous use of both assays allows to reduce positive and negative false results, for example, patients with normal DAO levels that could present a dysfunction in the activity of this enzyme.

Human diamine oxidase is readily released from activated neutrophils ex vivo and in vivo but is rarely elevated in bacteremic patients.

During human diamine oxidase (DAO) ELISA development we noticed that in serum DAO concentrations appear to be higher when compared to plasma. Neutrophils contain DAO in the specific granules and we hypothesized that DAO is released from neutrophils during serum coagulation. If activation of neutrophils can release DAO, its concentrations might be elevated in vivo after lipopolysaccharide (LPS) administration and in bacteremic patients. Using blood from healthy volunteers DAO concentrations were measured ex vivo in serum, citrate, EDTA and heparin plasma over several hours and after activation of neutrophils. Lipopolysaccharide and granulocyte-colony stimulating factor (G-CSF) were administered to 15 and 8 healthy volunteers, respectively and DAO concentrations were measured at different timepoints. DAO antigen levels were also determined in three different subcohorts of patients with culture-proven bacteremia and high C-reactive protein (CRP) levels. DAO concentrations were elevated in a time-dependent manner in serum but not in EDTA or citrate plasma (P < 0.01). Neutrophil activation using phorbol myristate acetate (PMA) and zymosan dose-dependently caused DAO concentrations to be elevated more than 10-fold at both 22°C and 37°C (both P-values <0.001). Administration of LPS to healthy volunteers released DAO from neutrophils (P < 0.001). Of the 55 different bacteremic patients selected from three independent cohorts only 3 (5.4%) showed highly elevated DAO concentrations. Serum DAO concentrations do not accurately reflect circulating enzyme levels but coagulation-induced neutrophil activation and consequently DAO release. Only a few bacteremic patients show high DAO concentrations able to degrade histamine rapidly.

The protective effect of procyanidin against LPS-induced acute gut injury by the regulations of oxidative state.

BackgroundA 2 × 4 factorial arrangement of treatments was used to investigate the protective effect of procyanidin (PCA) against lipopolysaccharide (LPS)-induced acute gut injury by the regulations of oxidative state for a 21-days feeding trial.MethodsA total of 384 1-days-old broiler chicks were assigned to 8 treatments with 8 replicate of 6 broiler chickens per pen. Broiler chickens fed diets based on 4 levels of dietary PCA (0, 0.05, 0.075 and 0.1 % of the requirements). Half of the birds from each treatment group were challenged with 0.9 % NaCl solution or LPS (250 μg/kg body weight, injection administered) at 16, 18 and 21 days of age.ResultsThe results indicated that, prior to LPS challenge, there was no dietary effect on bird growth performance (P > 0.05). The injection of LPS were also not associated with any significant changes in poultry performance (P > 0.05). But LPS injection increased serum diamine oxidase (DAO) level and the malondialdehyde (MDA) content of intestinal mucosa (P < 0.05), cause adverse effects to the morphology of the small intestine (P < 0.05), decreased the glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activity of intestinal mucosa (P < 0.05). When LPS-challenged birds were pretreated with PCA, serum DAO concentration and MDA activity in jejunal and ileal mucosa were dramatically attenuated, and improved the morphology of the small intestine as well (P < 0.05).ConclusionIn conclusion, PCA is able to prevent LPS-induced oxidative stress response in vivo, improved the morphology of the small intestine. The beneficial effect of PCA may depend on increasing the activity of body’s antioxidant enzymes and scavenging free radical activity.

Therapeutic hypothermia reduces intestinal ischemia/reperfusion injury after cardiac arrest in rats

To investigate the effects of therapeutic hypothermia (TH) on the morphology and function of intestine after cardiac arrest and resuscitation, 45 male rats were randomly assigned into three groups: (1) normothermia group, animals underwent ventricular fibrillation (VF) and cardiopulmonary resuscitation (CPR) with the rectal temperature maintained at 36.8 ± 0.2°C until 4 h after return of spontaneous circulation (ROSC); (2) hypothermia group, TH was induced with the aid of ice packs and an electrical fan because VF occurred and was maintained at 33.5 ± 0.5°C for 4 h after ROSC; (3) sham-operated group, animals underwent identical anesthetic and surgical procedures without VF, CPR or defibrillation. Five animals in each group were sacrificed at 4, 24 and 72 h post resuscitation. Serum diamine oxidase (DAO) and apoptosis rate of intestinal epithelial cells were tested by ELISA and flow cytometry, respectively. The concentration of FITC-Dextran that leaked out of enteric cavity was used to analyze the permeability of intestine. Histological changes were graded and compared among the three groups. Serum DAO concentrations in normothermia group reached the peak at 4 h post resuscitation, and then decreased at 24 and 72 h. In comparison with normothermia group, serum DAO concentrations were lower at 4 h in hypothermia group (0.97 ± 0.16 vs. 1.24 ± 0.29, P < 0.05). The amount of FITC-Dextran that passed the wall of small intestine in hypothermia group was signii¬cantly lower than that in normothermia group at 24 h after ROSC (7.81 ± 1.11 vs. 13.07 ± 3.07, P < 0.05). The amount of FITC-Dextran had no difference between normothermia and hypothermia groups at 4 and 72 h post resuscitation. The detached intestinal epithelial cells in hypothermia group showed significant lower frequency of apoptosis than those in normothermia group at 4 h (17.30 ± 2.56 vs. 25.63 ± 4.09, P < 0.05) and 24 h (9.38 ± 1.29 vs. 11.98 ± 1.78, P < 0.05). No obvious injury was observed in both normothermia and hypothermia groups at 4 h with grade of 0 to 1. The histopathological injury in normothermia group reached the peak at 24 h with grade of 2 to 3, which was significantly severe than that in hypothermia group with grade of 1 to 2. At 72 h post resuscitation, an almost complete restitution of the intestinal mucous could be observed both in hypothermia and normothermia groups. This study demonstrates that short term ischemia induced by cardiac arrest and resuscitation resulted in intestinal ischemia/reperfusion (IR) injury, which could be attenuated by therapeutic hypothermia. Key words: Rat, intestine, cardiac arrest, cardiopulmonary resuscitation, therapeutic hypothermia.