Protective effect of melatonin on experimental otitis media with effusion in guinea pigs

The aims of this study were: (a) to assess whether the increased oxidative stress in otitis media with effusion (OME) induced in guinea pigs by histamine injection into the middle ear cavity is reflected by lipid peroxidation in erythrocytes, plasma, and middle ear effusion fluid; (b) to survey the alterations of oxidant and antioxidant enzyme activities in experimental OME; and (c) to determine the effects of melatonin and methylprednisolone on this oxidative stress. Malondialdehyde (MDA) level, erythrocyte total (enzymatic plus non-enzymatic) superoxide scavenger activity (TSSA), non-enzymatic superoxide scavenger activity (NSSA), superoxide dismutase (SOD), catalase (CAT), and xanthine oxidase (XO) activities were measured in 4 groups of 7 guinea pigs at 3 hr after injection of 0.1 ml of histamine (or saline) into the middle ear. Group I was the control group, Group II was an experimental group with OME induced by histamine, Group III was a melatonin-pretreated OME group, and Group IV was a methylprednisolone-pretreated OME group. In erythrocyte, plasma, and middle ear effusion samples, MDA levels were significantly increased in guinea pigs with OME (Group II), compared to controls (Group I); erythrocyte TSSA and SOD activities were lower and erythrocyte XO activity was increased in guinea pigs with OME (Group II) compared to controls (Group I). No significant differences were found in erythrocyte NSSA and CAT activities. In Group III, pretreatment of guinea pigs with i.p. melatonin at 1 hr prior to histamine induction of OME decreased the erythrocyte, plasma, and effusion MDA levels, compared to Group II; erythrocyte XO activity was diminished and erythrocyte TSSA, SOD, and CAT activities were increased in Group III compared to Group II. In Group IV, pretreatment of guinea pigs with i.p. methylprednisolone at 1 hr prior to histamine induction of OME decreased the plasma and effusion MDA levels and increased the erythrocyte TSSA and SOD activities, compared to Group II. These results suggest that reactive oxygen species (ROS) play a role in histamine-induced OME. Pretreatment with i.p. melatonin or methylprednisolone both decrease the ROS generated by experimental OME, but melatonin appears to be more effective than methylprednisolone.     

Proteasome Subunit Beta Type-8 (PSMB8) Gene Polymorphisms in Vitiligo: A Possible Predictor of Auditory Involvement

IntroductionProteasome subunit beta type-8 (PSMB8) is a protein that contributes to the complete assembly of 20S proteasome complexes, which play a role in the pathogenesis of vitiligo.ObjectiveThe study aimed to evaluate the association between PSMB8 gene polymorphisms with vitiligo to assess its clinical significance among a sample of Egyptian patients with vitiligo.MethodsGenomic DNA was isolated from blood samples of 100 patients with vitiligo and 100 control subjects, and detection of PSMB8 polymorphisms was done by real-time PCR. Data analysis was carried out for the entire cohort. Statistics were performed using software. Audiological evaluation was performed, including pure-tone audiometry, extended high-frequency audiometry, transient evoked otoacoustic emissions, and auditory brainstem response.ResultsThere was a significant difference between PSMB8 genotypes and alleles distribution in patients and control groups. Ten percent of the study sample had sensorineural hearing loss. The patients with hearing loss were significantly older (P=0.0002), had significantly later age of onset (P=0.0007), longer duration (P=0.0021), higher body mass index (BMI) (P=0.045), and higher vitiligo area scoring index (VASI) scores (P=0.0015). All patients had extensive forms of vitiligo (generalized and universal). Regarding the VIT rs2071543 polymorphism, all of the patients with hearing loss were carrying the CA and AA genotypes. None of the patients carried the reference genotype, CC. The A allele of VIT rs2071543 was significantly associated with hearing affection (P=0.024).ConclusionIn our study, PSMB8 polymorphism was associated with the susceptibility to develop vitiligo and appeared to have clinical significance among the studied group of patients. Factors predicting auditory abnormalities should be further studied for early detection and management.     

Mucinous Pancreatic Cysts: Comparison of Cyst Size and Location in Certain Mucinous Cyst Subgroups

Background: There are studies reporting that the location of intraductal papillary mucinous neoplasia (IPMN) predicts malignancy. Therefore, we evaluated the cyst location’s relationship with malignancy, and the possibility of using cyst size and location to distinguish between non-main duct (non-MD)-IPMNs, mucinous cystic neoplasia (MCN), and cystic pancreatic ductal adenocarcinoma (PDAC).Methods: We performed a retrospective analysis of data from 122 patients with a definite cyto-histological diagnosis of non-MD-IPMNs, LR-MCNs, and cystic PDACs via endoscopic ultrasound fine-needle aspiration between October 2011 and October 2020. We grouped the cyst locations as head, uncinate, neck (HUN), and corpus or tail (CT). On histology, low-grade dysplasia and intermediate-grade dysplasia were considered low risk (LR), whereas high-grade dysplasia and invasive carcinoma were considered high risk (HR).Results: Of the 122 patients (61 (50%) women, median age 61.5 years (range 19-85), there were 34 (27.9%) LR-non-MD-IPMNs, 33 (27%) HR-non-MD-IPMNs, 19 (15.6%) LR-MCNs, and 36 (29.5%) cystic PDACs. We found no significant difference between LR- and HR-non-MD-IPMN locations (P = .803). Low-risk non-MD-IPMNs were significantly smaller than HR-non-MD-IPMNs (P < .001), LR-MCNs (P = .002), and cystic PDACs (P < .001). The area under the receiver operating characteristic curve (AUROC) was 0.819 (95% CI: 0.716-0.902; P < .0001), and demonstrated a cyst size cut-off <2.2 cm to differentiate LR cysts, while cysts <1.6 cm had a negative predictive value (NPV) of 100% in non-MD-IPMNs.Conclusion: Cyst location is not predictive of malignancy in non-MD-IPMNs. Low-risk non-MD-IPMNs were smaller than HR-non-MD-IPMNs, LR-MCNs, and cystic PDACs. The cyst size cut-off was 2.2 cm; however, <1.6 cm had a 100% NPV differentiating LR- from HR-non-MD-IPMNs.     

Mechanistic investigation of xanthene oxidation by heterogeneous and homogeneous electron transfers

Anodic oxidation of xanthene is investigated in acetonitrile at a platinum electrode by means of cyclic voltammetric and exhaustive potentiostatic electrolysis techniques. On the voltammetric scale time, the process involves two electrons and leads to xanthydrol. The corresponding mechanism is an ECE (electron–deprotonation–electron) type electrode reaction, the rate-determining step being the deprotonation of the cation radical obtained after the first electron transfer. On the other hand the analysis of the oxidation by homogeneous redox catalysis is carried out, using three organic catalysts. This allows the determination of the rate constants of the homogeneous electron transfers between xanthene and catalysts, the xanthene cation radical deprotonation rate constant and the standard potential of the xanthene cation radical/xanthene couple.