Production, purification, and characterization of p-diphenol oxidase (PDO) enzyme from lignolytic fungal isolate Schizophyllum commune MF-O5.

Fungi are producers of lignolytic extracellular enzymes which are used in industries like textile, detergents, biorefineries, and paper pulping. This study assessed for the production, purification, and characterization of novel p-diphenol oxidase (PDO; laccase) enzyme from lignolytic white-rot fungal isolate. Fungi samples collected from different areas of Pakistan were initially screened using guaiacol plate method. The maximum PDO producing fungal isolate was identified on the basis of ITS (internal transcribed spacer sequence of DNA of ribosomal RNA) sequencing. To get optimum enzyme yield, various growth and fermentation conditions were optimized. Later PDO was purified using ammonium sulfate precipitation, size exclusion, and anion exchange chromatography and characterized. It was observed that the maximum PDO producing fungal isolate was Schizophyllum commune (MF-O5). Characterization results showed that the purified PDO was a monomeric protein with a molecular mass of 68 kDa and showed stability at lower temperature (30 °C) for 1 h. The Km and Vmax values of the purified PDO recorded were 2.48 mM and 6.20 U/min. Thermal stability results showed that at 30 °C PDO had 119.17 kJ/K/mol Ea value and 33.64 min half-life. The PDO activity was stimulated by Cu2+ ion at 1.0 mM showing enhanced activity up to 111.04%. Strong inhibition effect was noted for Fe2+ ions at 1 mM showing 12.04% activity. The enzyme showed stability against 10 mM concentration oxidizing reducing agents like DMSO, EDTA, H2O2, NaOCl, and urea and retained more than 75% of relative activity. The characterization of purified PDO enzyme confirmed its tolerance against salt, metal ions, organic solvents, and surfactants indicating its ability to be used in the versatile commercial applications.

Superior mesenteric artery syndrome: An often overlooked cause of abdominal pain!

OBJECTIVES: To determine the prevalence of superior mesenteric artery (SMA) syndrome in patients presenting with abdominal pains, and to evaluate computed tomographic (CT) findings needed for its diagnosis. METHODS: This retrospective record-based study was carried out at the radiology department, from January 2016 to January 2021. All young patients (aged under 25) who underwent CT scans for abdominal pains were reviewed. Post-surgery, tumor, and trauma cases were excluded. Imaging findings for SMA syndrome were recorded as 'suggestive' (reduced aortomesenteric angle and distance with proximal duodenal dilatation), 'possible' (reduced angle and distance without proximal duodenal dilatation) and 'probable' (reduction of either angle or distance). Two radiologists interpreted the findings and consensus reporting was made. Diagnoses were confirmed on clinical grounds (symptomatic improvement by specific treatment and exclusion of other diagnoses), or barium studies. Imaging findings were compared to final diagnoses. McNemar's Chi-square test was used to determine association. RESULTS: Out of 141 patients (mean age=10.8, standard deviation=4), 7 (4.9%) patients mostly females were having SMA syndromes based on 'suggestive' imaging criteria (p=0.0005), and one patient underwent surgery. CONCLUSION: Superior mesenteric artery syndrome is not an uncommon condition and should be considered in differential diagnosis of acute abdomen in young patients after excluding other diagnoses.

Magnetic resonance imaging findings in patients with initial manifestations of perianal fistulas.

BACKGROUND: Crohn's disease (CD) is a serious cause of perianal disease and the incidence is increasing in Saudi Arabia. MR imaging may document specific features that may help to foresee Crohn's disease in patients making an initial presentation. OBJECTIVE: Present MR imaging findings of perianal fistulas in patients making an initial presentation. DESIGN: Retrospective, observational. SETTING: Radiology clinic in in Dhahran. PATIENTS AND METHODS: All previously undiagnosed and untreated patients who presented for the first time to the outpatient clinics from September 2015-2018 with perianal fistulas were retrospectively evaluated. Previously diagnosed CD patients, post-surgical or intervention cases were excluded. Fistulas were categorized as low or high anal, simple or complex, and were graded per St. James University Hospital Classification. Imaging was interpreted by two experienced readers based on the Van Assche score. MAIN OUTCOME MEASURES: Fistula features on MR imaging and diagnosis of CD. SAMPLE SIZE: 171 patients. RESULTS: Of 171 patients, 139 (81.3%) were males with mean age of 37.2 (12.7) years; the 32 females had a mean age of 35.8 (10.6) years. Twenty-one patients (12.3%) had CD. Fourteen (40.4%) patients with complex fistulas had CD in comparison to only 5 (4.8%) simple fistula patients ( P=.0005). More than half of patients with complex and high anal fistulas had CD ( P=.0005). Females were more affected than males ( P=.0005). CONCLUSION: Complex or high anal fistula on MR imaging may be the initial presentation of CD and warrant further work up to establish the diagnosis. LIMITATIONS: Retrospective, small sample, single center, and short duration study. CONFLICT OF INTEREST: None.