جستجوی مقالات مرتبط با کلیدواژه « brain » در نشریات گروه « پزشکی »

Some voxels may alter the tractography results due to unintentional alteration of noises and other unwanted factors. This study aimed to investigate the effect of local phase features on tractography results providing data are mixed by a Gaussian or random distribution noise. In this simulation study, a mask was firstly designed based on the local phase features to decrease false-negative and -positive tractography results. The local phase features are calculated according to the local structures of images, which can be zero-dimensional, meaning just one point (equivalent to noise in tractography algorithm), a line (equivalent to a simple fiber), or an edge (equivalent to structures more complex than a simple fiber). A digital phantom evaluated the feasibility current model with the maximum complexities of configurations in fibers, including crossing fibers. In this paper, the diffusion images were mixed separately by a Gaussian or random distribution noise in 2 forms: a zero-mean noise and a noise with a mean of data. The local mask eliminates the pixels of unfitted values with the main structures of images, due to noise or other interferer factors.  The local phase features of diffusion images are an innovative solution to determine principal diffusion directions.

Volumetric modulated arc therapy (VMAT) is mostly considered due to its superior tumor coverage and sparing of organs at risk (OAR) with shorter treatment delivery time. This study aimed to explore the feasibility and potential benefits of VMAT with a constant dose rate (CDR). In this analytical study, 75 cancer patients (15 from each cancer) were selected. Step and shoot intensity-modulated radiation therapy (S&S IMRT), CDR, and VDR VMAT (variable dose rate VMAT) plans were generated for each patient using the Monte Carlo algorithm on the Monaco treatment planning system for 6 MV photon energy. For dosimetric comparison, some variables were compared, including doses to the planning target volume (PTV), OAR, homogeneity index, conformity index (CI), treatment delivery time, and monitor units. CI was higher in CDR and VDR VMAT plans compared to IMRT without any significant variation for PTV coverage V95 and PTV mean dose. In the sparing of OAR, no significant variation was found between CDR, VDR, and IMRT for the brain, head-neck, oesophagus, lung, and prostate. The treatment delivery time was reduced more, i.e., by up to 72-80% in the CDR VMAT technique compared to IMRT.  CDR VMAT technique generates a clinically acceptable plan in terms of PTV coverage, dose conformity, and OAR sparing as IMRT and VDR VMAT in all five cancer sites.

High-quality images with minimum radiation dose are considered a challenge in Computed Tomography (CT) scans. The current study aimed to assess the efficacy of the Iterative Reconstruction in Image Space (IRIS) algorithm combined with Automatic Tube Current Modulation (ATCM) compared to Filtered Back Projection (FBP) in brain CT scans. In this cross-sectional study, 200 patients underwent to brain CT scan, and images were then reconstructed using both FBP and IRIS. The CT Number (CTN), noise, and Signal-to-Noise Ratio (SNR) were computed for different tissues from CT images. The performance of two algorithms under different exposure conditions was evaluated using a water phantom. Two experienced radiologists assessed the image quality. Volume CT Dose Index (CTDIvol) and Dose Length Product (DLP) were recorded for each scan. FBP reconstruction exhibited higher noise and lower SNR compared to IRIS, both with and without ATCM. Noise levels significantly increased for FBP combined with ATCM. Subjective analysis showed higher performance for IRIS without ATCM compared to other approaches. The mean CTDIvol with and without ATCM was 20.04±3.33 and 36.37±4.65 mGy, respectively. In the phantom study, the noise with IRIS remained lower than that with FBP even with a 42% dose reduction.  IRIS algorithm can preserve the image quality when radiation dose is significantly reduced by ATCM in brain CT scan. Implementation of IRIS combined with ATCM is recommended for brain CT examinations.

Interest in naturally occurring phytochemicals has been on the increase, they are believed to reduce the risk of brain disorders. Hispidulin (HN) is a phenolic flavonoid compound with various pharmacological and biological effects on the central nervous system. It belongs to the flavone class of flavonoids. It can be found in different plant materials, especially fruits and vegetables. The literature used in this review was collected from credible scientific databases including ScienceDirect, Scopus, PubMed, Google Scholar, and Hindawi without time restriction, using relevant keywords, such as HN, brain, central nervous system, flavonoids, and flavones. HN was discovered to possess pro-apoptotic properties, act as an antioxidant, inhibit cytokine production and toll-like receptor 4 expression, as well as impede nuclear factor kappa beta and mitogen-activated protein kinase B. HN was also found to inhibit lipid peroxidation in vitro and reduce brain edema in mice. These pharmacological potentials suggest that HN is a promising candidate for neuroprotection in CNS disorders like depression and epilepsy. This review provides an update on the scientific literature concerning how these activities could help provide various forms of neuroprotection in the CNS. Additional experimental data on the effects of HN in models of neurological disorders and neuroprotection should be explored further. Based on the current study, HN is a promising candidate for neuroprotection of the CNS.

Maternal separation (MS) is a well-characterized model of early life stress, based on the postnatal disruption of the mother-infant interaction. Studies on rodents have demonstrated that MS, as an early adverse life event, leads to spatial memory deficits and lasting changes in brain plasticity. Here, we review data from animal studies regarding the impact of MS on long-term potentiation (LTP). Evidence shows that animal models are useful for evaluating the effects of MS on LTP. Overall, studies suggest that MS impairs LTP.

Numerous physical and chemical agents can induce destructive effects on the brain tissue. Noise and toluene, which are some of these harmful agents, have significant adverse effects on the brain tissue. This work aimed to investigate the neurotoxic changes induced by co-exposure to toluene and noise. 

A total of 24 male white New Zealand rabbits were randomly segregated into four groups, including toluene exposure, noise exposure, co-exposure to noise and toluene, and control. This in vivo study tested the neurotoxic effects of exposure to 1000 ppm toluene and 100 dB noise during two weeks (8 h/day). The serum levels of brain-derived neurotrophic factor-α (BDNF-α), malondialdehyde (MDA), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase and total antioxidant capacity (TAC) values in the brain tissue were measured. Moreover, hematoxylin and eosin (H&E) staining was utilized for brain pathological analysis.

Exposure to noise increased TAC values in the cerebral cortex. Co-exposure to toluene and noise increased the serum levels of BDNF-α. Nevertheless, exposure to noise decreased the levels of BDNF-α in serum. On the other hand, histopathological examinations using H&E staining exhibited that different signs of inflammation, such as lymphocyte infiltration, pyknosis, vacuolization, and chromatolysis were induced by exposure to noise and toluene in the cerebellum, hippocampus, and frontal section in the brain tissue. In addition, simultaneous exposure to toluene and noise induced antagonistic and synergistic changes in some neurotoxic parameters.

Exposure to noise and toluene, which caused inflammation in the brain tissue cells, could be a noticeable risk factor for the neurological system.

Hypoxic-ischemic encephalopathy (HIE) is still a relevant cause of neonatal mortality and morbidity. HIE severity can predict long-term outcomes. Sarnat staging is one of the most common methods used to evaluate HIE severity. However, an ongoing urge exists to find other accurate and affordable ways to accompany this clinical staging for HIE. This study aimed to evaluate the relationship between cerebral arteries’ resistive indices and other hypoxic-ischemic encephalopathy indicators using Sarnat scoring of newborns subjected to perinatal asphyxia.

In this retrospective study, 76 neonates with gestational age ≥34 weeks affected with HIE were investigated. The patients were categorized into three groups according to Sarnat staging: I, II, and III. Initially, perinatal data were analyzed to assess the correlation between HIE severity and various factors such as gestational age, type of delivery, Apgar scores, necessity for resuscitation, and requirement for respiratory assistance. Notably, these relationships were significant.

Examining various symptoms in different HIE stages showed that the incidence of coagulopathy was significantly higher in severe HIE neonates than in mild neonates. Eventually, proposedly, cranial arterial Doppler indices, i.e., the anterior cerebral artery’s resistive index (RI), significantly differed between HIE stage groups.

This study represented a combination of available and affordable data to achieve early HIE staging, including perinatal data, clinical symptoms, and a bedside Doppler ultrasonography of cerebral perfusion. Higher cranial artery RI was associated with severe HIE and could be considered for therapeutic hypothermia, which may reduce HIE mortality and morbidity.

The process of vascular formation, also known as angiogenesis, primarily relies on endothelial cell proliferation, migration, and invasion. In recent years, it has been discovered that synthetic cannabinoids (SCs) may potentially impact angiogenic processes within the body. We evaluated the impact of the synthetic cannabinoid (R)-5-Fluoro-ADB on the proliferation rate and angiogenesis in Human Cerebral Microvascular Endothelial Cells (hBMECs).  hBMECs were treated with (R)-5-Fluoro-ADB and investigated for cell viability, migration rate, and tube-like structure formation. Furthermore, angiogenic-related proteins including Angopoitein-1 and -2, and Vascular Endothelial Growth Factors (VEGF) were examined on mRNA and protein levels. The results showed a notable rise in the rate of proliferation (P-value<0.0001) of HBMECs induced by (R)-5-Fluoro-ADB. The angiogenic capacity of HBMECs was also enhanced between 0.001 μM to 1 μM (R)-5-Fluoro-ADB. Moreover, an increase in the levels of ANG-1, ANG-2, and VEGF mRNA and protein, as well as elevated phosphorylation rate of GSK-3β, were observed across various concentrations of (R)-5-Fluoro-ADB. Our results suggest an innovative approach in pharmacology for addressing a range of conditions linked to angiogenesis. This approach involves precise targeting of both cannabinoid receptors type-1 and -2. To achieve this, specific agonists or antagonists of these receptors could be employed based on the particular characteristics of the diseases in question.

Methanol is a toxic alcohol for the human body. The molecular biology of methanol metabolites affecting different organs, such as the brain, is under investigation. This systematic review aimed to consider methanol toxic molecular biology, based on the original articles obtained from data banks to figure out recent achievements.

Scientific articles regarding the toxic effects and metabolites of methanol on the central nervous system (CNS) were collected from valid databases and classified based on their validity. Exclusion criteria were articles with duplicates, no available full text, review articles, case reports, and letters.

Current metabolic reactions were addressed in the development of CNS diseases, such as optic neuropathy, basal ganglia lesions, and Alzheimer’s disease. However, proteomic investigations introduced new metabolic changes, and serum proteins regarding blood coagulation, vitamin A metabolism, and immune responses were suggested for early detection of toxicity.

Besides CNS disorders introduced for methanol toxicity, there is no exact proteomic serum marker to diagnose toxicity soon; however, the interleukin-1 beta system is suggested as a candidate, and more investigation is required to improve its competency.

Living Donor Liver Transplantation (LDLT) is a promising approach to treating end-stage liver diseases, however, some post-operatory complications such as pneumonia, bacteremia, urinary tract infections, and hepatic dysfunction have been reported. In murine models using partial hepatectomy (PHx), a model that emulates LDLT, it has been determined that the synthesis of hepatic cell proliferation factors that are associated with noradrenaline synthesis are produced in locus coeruleus (LC). In addition, studies have shown that PHx decreases GABA and 5-HT2A receptors, promotes loss of dendritic spines, and favors microgliosis in rat hippocampus. The GABA and serotonin-altered circuits suggest that catecholaminergic neurons such as dopamine and noradrenaline neurons, which are highly susceptible to cellular stress, can also be damaged. To understand post-transplant affections and to perform well-controlled studies it is necessary to know the potential causes that explain as a liver surgical procedure can produce brain damage. In this paper, we review several cellular processes that could induce gliosis in LC after rat PHx.

The present study is devoted to the study of brain activation using fMRI in patients with depression (after acute coronary syndrome and somatically healthy) and in healthy volunteers.

The study enrolled a total of 51 patients: 11 with depression after acute coronary syndrome, 16 with primary depressive episode and recurrent depression without prior coronary event, and 24 with ACS without depression. The groups were matched by sex and age. The emotional information processing was evaluated with the Pennsylvania Test of Emotion Recognition. All patients underwent fMRI at the time of this test. The data processing was performed with SPM12 and xjView applications.

During the processing of emotional information in the depressed patients after ACS, specific activation zones in the frontal cortex (P < 0.001), right fusiform gyrus (P < 0.001), and right insular lobe were identified (P = 0.017). In the patients with primary depressive episode and recurrent depression without ACS, certain zones of activation were identified in frontal cortex (P < 0.001; 0.001), left fusiform gyrus (P < 0.001), occipital cortex (P < 0.001). In the patients who had ACS, without depression, some zones of activation were specified in the right middle occipital gyrus (P < 0.001), the right superior frontal gyrus (P = 0.088), and the putamen projection on the right (P < 0.001) and on the left (P = 0.009), as well as the left insular lobe (P = 0.015).

The pathogenesis of depression is significantly associated with the peculiarities of processing emotionally significant information, regardless of the conditions under which it develops.

Recent studies have utilized innovative techniques to investigate the neural mechanisms underlying social and individual decision-making, aiming to understand how individuals respond to the world.

In this review, we summarized current scientific evidence concerning the neural underpinnings of social decision-making and their impact on social behavior.

Critical brain regions involved in social cognition and decision-making are integral to the process of social decision-making. Notably, the medial prefrontal cortex (mPFC) and temporoparietal junction (TPJ) contribute to the comprehension of others' mental states. Similarly, the posterior superior temporal sulcus (pSTS) shows heightened activity when individuals observe faces and movements. On the lateral surface of the brain, the inferior frontal gyrus (IFG) and inferior parietal sulcus (IPS) play a role in social cognition. Furthermore, the medial surface of the brain, including the amygdala, anterior cingulate cortex (ACC), and anterior insula (AI), also participates in social cognition processes. Regarding decision-making, functional magnetic resonance imaging (fMRI) studies have illuminated the involvement of a network of brain regions, encompassing the ventromedial prefrontal cortex (vmPFC), ventral striatum (VS), and nucleus accumbens (NAcc).

Dysfunction in specific subregions of the prefrontal cortex (PFC) has been linked to various psychiatric conditions. These subregions play pivotal roles in cognitive, emotional, and social processing, and their impairment can contribute to the development and manifestation of psychiatric symptoms. A comprehensive understanding of the unique contributions of these PFC subregions to psychiatric disorders has the potential to inform the development of targeted interventions and treatments for affected individuals.

Coronavirus disease 2019 (COVID-19) is a multisystem disease, manifested by several symptoms of various degrees. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) can affect the central nervous system (CNS) through several mechanisms and brain imaging plays an essential role in the diagnosis and evaluation of the neurological involvement of COVID-19. Moreover, brain imaging of patients with COVID-19 would result in a better understanding of SARS-CoV-2 neuro-pathophysiology. In this study, we evaluated the brain imaging findings of patients with COVID-19 in Shohada-e Tajrish Hospital, Tehran, Iran.

This was a single-center, retrospective, and observational study. The hospital records and chest and brain computed tomography (CT) scans of patients with confirmed COVID-19 were reviewed.

161 patients were included in this study (39.1% women, mean age: 60.84). Thirteen patients (8%) had ischemic strokes identified by brain CT. Subdural hematoma, subdural effusion, and subarachnoid hemorrhage were confirmed in three patients. Furthermore, there were four cases of intracranial hemorrhage (ICH) and intraventricular hemorrhage (IVH). Patients with and without abnormal brain CTs had similar average ages. The rate of brain CT abnormalities in both genders did not differ significantly. Moreover, abnormal brain CT was not associated with increased death rate. There was no significant difference in lung involvement (according to lung CT scan) between the two groups.

Our experience revealed a wide range of imaging findings in patients with COVID-19 and these findings were not associated with a more severe lung involvement or increased rate of mortality.

Cerebrovascular diseases comprise a significant portion of neurological disorders related to coronavirus disease 2019 (COVID-19). We evaluated the clinical and imaging characteristics of a cohort of COVID-19 patients with stroke and also identified patients with watershed infarcts.

In this cross-sectional study, seventy-three COVID-19 patients with ischemic stroke were included between October 2020 and January 2021. Patients were evaluated based on the following clinical and imaging features: severity of COVID-19 (critical/non-critical), stroke type, presence/absence of clinical suspicion of stroke, medical risk factors, Fazekas scale, atherothrombosis, small vessel disease, cardiac pathology, other causes, and dissection (ASCOD) criteria classification, and presence or absence of watershed infarction. Clinical outcomes were assessed based on Modified Rankin Scale (MRS) and mortality.

Most cases of ischemic stroke were due to undetermined etiology (52.1%) and cardioembolism (32.9%). In terms of imaging pattern, 17 (23.0%) patients had watershed infarction. Watershed infarction was associated with the clinically non-suspicious category [odds ratio (OR) = 4.67, P = 0.007] and death after discharge (OR = 7.1, P = 0.003). Patients with watershed infarction had a higher odds of having high Fazekas score (OR = 5.17, P = 0.007) which was also shown by the logistic regression model (adjusted OR = 6.87, P = 0.030). Thirty-one (42%) patients were clinically non-suspected for ischemic stroke. Critical COVID-19 was more common among patients with watershed infarct and clinically non-suspicious patients (P = 0.020 and P = 0.005, respectively). Patients with chronic kidney disease (CKD) were more prone to having stroke with watershed pattern (P = 0.020).

Watershed infarct is one of the most common patterns of ischemic stroke in patients with COVID-19, for which clinicians should maintain a high index of suspicion in patients with critical COVID-19 without obvious clinical symptoms of stroke.