Molecular identification and phylogenetic analysis of free-living amoeba in the water resources of Arak, Iran

The aim of the present study was to detect free-living amoeba (FLA) in the water resources of Arak, Iran using molecular tools. A total of 154 samples were collected from different water supplies. Molecular analyses, sequencing, and phylogenetic study were conducted to confirm the species and genotypes of FLA. Fisher exact test was used to determine the significance. Of 154 water samples, 19 (12.3%) samples were tested positive for FLA. Three genotypes of Acanthamoeba including T4, subtype D, and T5 were identified among the isolates. The pathogenicity assay showed that the isolate of Acanthamoeba in drinking water was highly pathogenic. Three species of Naegleria, including N. australiensis, N. pagei, and N. gruberi were found among the samples. Six isolates of Vermamoeba were identified as V. vermiformis. Meanwhile, three other species including Vannella sp., Vahlkampfia avara, and Stenamoeba polymorpha were also recovered from the water samples. Statistical analysis showed a significant difference between the various water resources contaminated with FLA. This is the first study to reveal the presence of S. polymorpha in water sources in Iran. According to the findings of the present study, health officials should be beware of potential public health impacts of FLA in water resources

Predominance of Trichophyton tonsurans causing tinea capitis: A 12-year retrospective study in the north of Iran

Background and purpose: Among different clinical entities of dermatophytosis, tinea capitis (TC) is considered a major public health challenge in the world, especially in regions with poor health and low income. Therefore, this study aimed to provide a retrospective analysis of the patients suspected of TC who were referred to the medical mycology laboratory of Mazandaran, a northern province of Iran.Materials and Methods: A retrospective analysis was performed on the patients suspected of TC who were referred to the medical mycology laboratory from July 2009 to April 2022. Hair roots and skin scrapings were collected from the participants. The laboratory diagnosis was confirmed by direct microscopic examination and culture. Finally, 921 out of 11095 (8.3%) patients were suspected of TC.Results: Based on the findings, TC was confirmed in 209 out of 921 patients (22.7%). In terms of gender, 209 TC patients (75.1%) were male. Moreover, the male to female ratio of TC patients was 1:3.0. Trichophyton tonsurans (146/174, 83.91%) was the most etiological agent,followed by T. mentagrophytes (13/174, 7.47%), T. violaceum (9/174, 5.17%), Microsporum canis (3/174, 1.71%), T. verrucosum (2/174, 1.15%) and T. rubrum (1/174, 0.57%). Besides, endothrix (77.0%) was the most prevalent type of hair invasion.Conclusion: The results revealed the predominance of T. tonsurans, as a causative agent of TC. Despite the prevalence of TC, the absence of appropriate consideration highlights that it is a neglected complication among children

Dosage-Dependent Impact of Acute Serotonin Enhancement on Transcranial Direct Current Stimulation Effects

BACKGROUND: The serotonergic system has an important impact on basic physiological and higher brain functions. Acute and chronic enhancement of serotonin levels via selective serotonin reuptake inhibitor administration impacts neuroplasticity in humans, as shown by its effects on cortical excitability alterations induced by non-invasive brain stimulation, including transcranial direct current stimulation (tDCS). Nevertheless, the interaction between serotonin activation and neuroplasticity is not fully understood, particularly considering dose-dependent effects. Our goal was to explore dosage-dependent effects of acute serotonin enhancement on stimulation-induced plasticity in healthy individuals. METHODS: Twelve healthy adults participated in 7 sessions conducted in a crossover, partially double-blinded, randomized, and sham-controlled study design. Anodal and cathodal tDCS was applied to the motor cortex under selective serotonin reuptake inhibitor (20 mg/40 mg citalopram) or placebo medication. Motor cortex excitability was monitored by single-pulse transcranial magnetic stimulation. RESULTS: Under placebo medication, anodal tDCS enhanced, and cathodal tDCS reduced, excitability for approximately 60–120 minutes after the intervention. Citalopram enhanced and prolonged the facilitation induced by anodal tDCS regardless of the dosage while turning cathodal tDCS-induced excitability diminution into facilitation. For the latter, prolonged effects were observed when 40 mg was administrated. CONCLUSIONS: Acute serotonin enhancement modulates tDCS after-effects and has largely similar modulatory effects on motor cortex neuroplasticity regardless of the specific dosage. A minor dosage-dependent effect was observed only for cathodal tDCS. The present findings support the concept of boosting the neuroplastic effects of anodal tDCS by serotonergic enhancement, a potential clinical approach for the treatment of neurological and psychiatric disorders

Cognitive functions and underlying parameters of human brain physiology are associated with chronotype

Circadian rhythms have natural relative variations among humans known as chronotype. Chronotype or being a morning or evening person, has a specific physiological, behavioural, and also genetic manifestation. Whether and how chronotype modulates human brain physiology and cognition is, however, not well understood. Here we examine how cortical excitability, neuroplasticity, and cognition are associated with chronotype in early and late chronotype individuals. We monitor motor cortical excitability, brain stimulation-induced neuroplasticity, and examine motor learning and cognitive functions at circadian-preferred and non-preferred times of day in 32 individuals. Motor learning and cognitive performance (working memory, and attention) along with their electrophysiological components are significantly enhanced at the circadian-preferred, compared to the non-preferred time. This outperformance is associated with enhanced cortical excitability (prominent cortical facilitation, diminished cortical inhibition), and long-term potentiation/depression-like plasticity. Our data show convergent findings of how chronotype can modulate human brain functions from basic physiological mechanisms to behaviour and higher-order cognition