Dietary Fiber in Inflammatory Bowel Disease: Are We Ready to Change the Paradigm?

Accumulating evidence from pre-clinical and clinical studies demonstrate the benefit of dietary fibers for inflammatory bowel disease (IBD). However, the majority of patients avoid or limit their consumption to manage their symptoms during the active and remission phases, although limited research supports these long-term dietary habits. Although recent evidence-based dietary guidelines highlight the importance of promoting an adequate intake of dietary fiber in IBD patients, intervention trials have not yet clearly clarified the quality and quantity of dietary fiber that should be consumed to be equally tolerated by and provide benefit for patients with IBD. This narrative review describes dietary fibers and their characteristics, analyzes the real-word studies on the impact of dietary fiber consumption in IBD in different clinical settings, and concludes with potential future directions in fiber research, focusing on the real-world needs of characterizing the consumption of fiber-rich foods and promoting their adequate intake.

Endoscopic Resection for Duodenal Neuroendocrine Neoplasms between 10 and 20 mm-A Systematic Review and Meta-Analysis

Background. The optimal management of duodenal neuroendocrine neoplasms (dNENs) sized 10-20 mm remains controversial and although endoscopic resection is increasingly performed instead of surgery, the therapeutic approach in this setting is not fully standardized. We performed a systematic review of the literature and a meta-analysis to clarify the outcomes of endoscopic resection for 10-20 mm dNENs in terms of efficacy (i.e., recurrence rate) and safety. Methods. A computerized literature search was performed using relevant keywords to identify pertinent articles published until January 2023. Results. Seven retrospective studies were included in this systematic review. The overall recurrence rate was 14.6% (95%CI 5.4-27.4) in 65 patients analyzed, without significant heterogeneity. When considering studies specifically focused on endoscopic mucosal resection, the recurrence rate was 20.5% (95%CI 10.7-32.4), without significant heterogeneity. The ability to obtain the free margin after endoscopic resection ranged between 36% and 100%. No complications were observed in the four studies reporting this information. Conclusions. Endoscopic resection could be the first treatment option in patients with dNENs sized 10-20 mm and without evidence of metastatic disease. Further studies are needed to draw more solid conclusions, particularly in terms of superiority among the available endoscopic techniques.

Diagnostic Yield of Small Bowel Videocapsule Endoscopy in Patients with Iron Deficiency Anemia. A Systematic Review and meta-analysis

BACKGROUND AND AIM

Gastrointestinal (GI) bleeding or malabsorption represents the most frequent aetiologies of iron deficiency anemia (IDA). The cause of IDA remains undetermined in ~10% to 20% of patients undergoing upper and lower GI endoscopies. In this scenario, a small bowel examination with videocapsule endoscopy (VCE) is recommended. We performed a systematic review with meta-analysis to evaluate the diagnostic yield of VCE in patients with IDA without overt bleeding, assessing the prevalence of either any lesion or lesions at high potential of bleeding.

MATERIALS AND METHODS

A computerized literature search was performed using relevant keywords to identify all the pertinent articles published until March 2023.

RESULTS

Twelve studies with a total of 1703 IDA patients (Males: 47%; age range: 19-92 y) were included in this systematic review. The diagnostic yield of VCE for overall lesions in the small bowel was 61% (95% CI=44-77; 95 CI=97.2-98.1; I2=97.7%). When analyzing only small bowel lesions likely responsible of IDA, the diagnostic yield was 40% (95% CI=27-53; 95% CI=95.3-97; I2=96.3%).

CONCLUSION

VCE plays a relevant role in the diagnostic work-up of patients with IDA without overt bleeding with a satisfactory diagnostic yield.

Exploring the link: Porto-sinusoidal vascular disorder and inflammatory bowel disease - A comprehensive narrative review

Porto-sinusoidal vascular disorder (PSVD) encompasses a group of vascular disorders characterized by lesions involving the portal venules and sinusoids, independent of the presence of portal hypertension (PH), and for which liver biopsy is essential for diagnosis. PSVD has been shown to be common in patients with immune-mediated diseases, including inflammatory bowel disease (IBD). The association between PSVD and the use of thiopurines and thioguanine in patients with IBD has been well established. In addition, research suggests an association between PSVD and IBD, even in cases where patients haven't been exposed to specific medications, probably related to changes in intestinal permeability. The identification and management of patients with known IBD and PSVD is a challenge for gastroenterologists. This narrative review aims to summarize the currently available data on the association between IBD and PSVD and provide practical suggestions for the management of this group of patients.

The Use of a New Dedicated Electrocautery Lumen-Apposing Metal Stent for Gallbladder Drainage in Patients with Acute Cholecystitis

Aims: Lumen-apposing metal stents (LAMSs) in ultrasonography-guided gallbladder drainage (EUS-GBD) have become increasingly important for high-risk surgical patients. Our study aims to evaluate the technical and clinical success, safety, and feasibility of endoscopic ultrasonography-guided gallbladder drainage using a new dedicated LAMS. Methods: This is a retrospective multicenter study that included all consecutive patients not suitable for surgery who were referred to a tertiary center for EUS-GBD using a new dedicated electrocautery LAMS for acute cholecystitis at eight different centers. Results: Our study included 54 patients with a mean age of 76.48 years (standard deviation: 12.6 years). Out of the 54 endoscopic gallbladder drainages performed, 24 (44.4%) were cholecysto-gastrostomy, and 30 (55.4%) were cholecysto-duodenostomy. The technical success of LAMS placement was 100%, and clinical success was achieved in 23 out of 30 patients (76.67%). Adverse events were observed in two patients (5.6%). Patients were discharged after a median of 5 days post-stenting. Conclusions: EUS-GBD represents a valuable option for high-surgical-risk patients with acute cholecystitis. This new dedicated LAMS has demonstrated a high rate of technical and clinical success, along with a high level of safety.

Effect of Oral Contraceptives on Lacrimal Fluid Peroxidase Activity in Women

Lacrimal fluid peroxidase has been supposed to be involved in the protection against oxidative damage to the ocular surface. Our recent findings showed the existence of significant cyclic variations in lacrimal fluid peroxidase activity that were positively correlated with those of 17beta-estradiol plasma levels throughout the menstrual cycle of fertile women. In the present study lacrimal fluid peroxidase activity of 8 healthy normocyclic women using low-dose oral contraceptives during the monthly cycle was determined. Data showed that low-dose oral contraceptives caused a decrease in lacrimal fluid peroxidase activity and a lack of its cyclic pattern with respect to the enzyme activity of 8 untreated age-matched women. Moreover, this result suggests that lacrimal fluid peroxidase activity could be regulated by estrogen.

Variations of lacrimal fluid peroxidase activity in female and male rats

Previous research from this laboratory showed that human lacrimal fluid peroxidase has cyclic variations during the menstrual cycle, correlated with plasma levels of 17beta-oestradiol. In the present investigation, variations of enzyme activity and total protein content during the oestrous cycle of young adult female rats are analysed. Effects from circadian rhythm and a gender-related influence are also examined. In female rats, as in women, lacrimal fluid peroxidase activity shows cyclic variations; in fact, it significantly (p < 0.05) changes during the different phases of the oestrous cycle. In contrast, in males such variations do not occur. Thus, we suggest that gender seems to exert a significant influence on the secretion of this specific tear protein, probably by a direct effect of oestrogens.

Antiproliferative effect and apoptotic response in vitro of human melanoma cells to liposomes containing the ribosome-inactivating protein luffin

The present study describes the liposome-mediated delivery of the type 1 ribosome-inactivating protein luffin to human melanoma cells in vitro. Luffin from Luffa cylindrica seeds has been successfully incorporated into lecithin/cholesterol and lecithin/cholesterol/dicetylphosphate negatively charged liposomes. The exposure of melanoma cells to the two types of liposomes resulted in the inhibition of protein synthesis and cell growth; apoptotic cell death was verified by means of TUNEL reaction and quantitation of cytosolic oligonucleosome-bound DNA. The toxicity of encapsulated luffin varied with the lipid composition of the vesicles; the strongest effect was observed with lecithin/cholesterol liposomes. These results identify liposome-incorporated luffin as a possible alternative to immunotoxins for the treatment of human melanoma in situ.

Type B monoamine oxidase activity in human brain malignant tumors

An increase of monoamine oxidase (MAO) activity was observed in Central Nervous System (CNS) malignant tumors, but the isoform responsible was not identify (Marcozzi et al., 1985). In the present work we report additional data in order to ascertain whether the type A or B MAO isoform is increased in some malignant human tumors of CNS. In the homogenated tissues the amine oxidase activity was determined by the chemiluminescent method, using different and specific substrates or inhibitors of MAO A and B and copper-dependent enzymes. 19 samples from 4 different types of tumors and relative peritumoral tissues were analysed. The highest activity of was imputable to type B MAO.

Effects of surfactants on the stabilization of the bovine lactoperoxidase activity

Bovine lactoperoxidase (LPO) is taken as a model protein of mammalian peroxidases to investigate the activity and the stability of the enzyme in the presence of different surfactants. The cationic benzalkonium chloride (Bz) has proved efficient in preserving the enzymatic activity for over 10 days, while the native enzyme completely lost its activity within 3-4 days. The presence of Bz allows the enzyme to preserve its secondary structure for a long time, as shown in CD spectra, and creates a more hydrophobic environment for the enzyme, as indicated in fluorescence studies. Moreover, this surfactant at a concentration of 0.01% (0.3 mM) increases the lactoperoxidase activity in the first 2 h of incubation at 37 degrees C. Both hydrophobic and electrostatic interactions of the cationic surfactant seem to be responsible for the enzyme activation and stabilization, and this is a promising result in view of industrial applications of enzymes.

A simple method for the purification of type 1 RIPs

We describe a straightforward and simple method for obtaining pure and active preparations of type 1 ribosome inactivating proteins (RIPs). The very high isoelectric point values, characteristic of these proteins, allow this purification in a single chromatographic step.

A rapid procedure for the purification of human salivary peroxidase

An improvement to the purification method for human salivary peroxidase is presented. The enzyme is obtained at a higher degree of purity in two chromatographic steps instead of four, and avoiding lyophilation treatment. Differences in electrophoretic pattern confirm the genetic polymorphism of the peroxidase of human saliva.

Inhibition of copper-dependent amine oxidases by some hydrazides of pyrrol-1-ylbenzoic and pyrrol-1-ylphenylacetic acids

Some hydrazides of pyrrol-1-ylbenzoic and pyrrol-1-ylphenylacetic acids were prepared, and their effect on copper-dependent amine oxidases (Cu-AOs) and FAD monoamine oxidases (MAOs) activities was tested. The compounds were not substrates for Cu-AO enzymes but acted as noncompetitive inhibitors. Hydrazides of pyrrol-1-ylphenylacetic acids were highly specific for plasma amine oxidase (Ki = 0.5-1 microM). In contrast, all the hydrazides were weak inhibitors of MAO activity. Incubation with the hydrazide derivatives led to irreversible inactivation of Cu-AOs. Therefore, the inhibition implied two distinct steps. The first one consisted of the rapid formation of the enzyme-inhibitor complex and was reversed by dialysis. In the second step, the complex was irreversibly transformed, probably by the formation of a Schiff base between the hydrazide and the prosthetic carbonyl group of the enzyme.

Determination of amine oxidases in tissues by peroxidation-induced chemiluminescence of phthalazines

A method is proposed for the determination of the activity of amine oxidases in purified samples and tissue homogenates. The method is based on the chemiluminescence of luminol and other cyclic hydrazides elicited by the horseradish peroxidase-catalyzed peroxidation using H2O2 produced in the amine oxidase reaction. Several aspects of the chemiluminescence method for determining enzymatic activity in crude tissue extracts are discussed.

Pulse-radiolysis studies on the interaction of one-electron reduced species with blue oxidases. Reduction of type-2-copper-depleted ascorbate oxidase

The interaction of one-electron reduced metronidazole (ArNO2.-) with native and Type-2-copper-depleted ascorbate oxidase were studied in buffered aqueous solution at pH 6.0 and 7.4 by using the technique of pulse radiolysis. With ArNO2.-, reduction of Type 1 copper of the native enzyme and of the Type-2-copper-depleted ascorbate oxidase occurs via a bimolecular step and at the same rate. Whereas the native protein accepts, in the absence of O2, 6-7 reducing equivalents, Type-2-copper-depleted ascorbate oxidase accepts only 3 reducing equivalents with stoichiometric reduction of Type 1 copper. On reaction of O2.- with ascorbate oxidase under conditions of [O2.-] much greater than [ascorbate oxidase], removal of Type 2 copper results in reduction of all the Type 1 copper atoms, in contrast with reduction of the equivalent of only one Type 1 copper atom in the holoprotein. From observations at 610 nm, the rate of reduction of ascorbate oxidase by O2.- is not dependent on the presence of Type 2 copper. For the holoprotein, no significant optical-absorption changes were observed at 330 nm. It is proposed that electrons enter the protein via Type 1 copper in a rate-determining step followed by a fast intramolecular transfer of electrons within the protein. For the Type-2-copper-depleted protein, intramolecular transfer within the protein, however, is slow or does not occur. In the presence of O2, it is also suggested that re-oxidation of the partially reduced holoprotein occurs at steady state, as inferred from the observations at 330 nm and 610 nm. The role of Type 2 copper in ascorbate oxidase is discussed in terms of its involvement in redistribution of electrons within the protein or structural considerations.

A new crystalline modification of the copper enzyme ascorbate oxidase

The copper enzyme ascorbate oxidase, purified from green zucchini squash, has been crystallized at pH 5.4 employing the organic solvent 2-methyl-2,4-pentanediol. The crystals obtained are larger than one millimetre and belong to the space group P2(1)2(1)2, with unit cell parameters; a = 106.7 A, b = 105.1 A, c = 113.5 A. The crystallographic asymmetric unit contains two subunits of the enzyme (Mr = 140,000) and the solvent content of the crystals is 46% (v/v). The diffraction pattern extends to 2.5 A resolution; this crystal form is suitable for a X-ray structural investigation.

A reinvestigation on the quaternary structure of ascorbate oxidase from Cucurbita pepo medullosa

The optical properties, copper content, catalytic activity and quaternary structure of many preparations of ascorbate oxidase purified with two different methods were examined. Fresh samples appeared identical and were characterized by optical ratios A280/A610 = 25 +/- 1 and A330/A610 = 0.8 +/- 0.05, by specific activity toward ascorbate of 3.48 +/- 0.05 mol g-1 min-1 and by a copper content of 8 +/- 0.3 mol/145 000 Mr. The enzyme is composed of two non-covalently linked subunits of slightly different molecular mass (75 000 and 72 000 respectively). These subunits cannot be further resolved by reduction of disulfide bonds. Proteolytic cleavage of the protein chains was observed during purification and storage in the absence of the protease inhibitor 6-amino caproic acid. Ascorbate oxidase exists as a monomer at neutral pH and undergoes reversible association into higher molecular weight species at slightly acid pH values. Association is not accompanied by spectroscopic or catalytic changes.