Ivan Dimitrijevic

Relationship between internet use and depression

A cross-sectional observational study was conducted on a sample of 336 adolescents.There was a positive correlation between internet addiction and depression.The detected relationship is independent from social networking activities. The aim of the research was to investigate the potential relationship between internet addiction and depression in adolescents. A cross-sectional observational study was conducted on a sample of 336 high school students in Belgrade, Serbia. Each student was given a questionnaire consisting of Center for Epidemiologic Studies of Depression Scale for Children (CES-DC), Young Internet Addiction Test (IAT) as well as general questions related to internet and social networking site (SNS) use. The results of our study indicate that internet use and level of internet addiction measured with IAT scale are positively correlated with depressive symptoms. No such relationship existed between the time spent on social networking sites and depression, as well as between depression symptoms and SNS-related activities such as the number of Facebook friends. Neither the time spent on SNSs nor SNS-related activities had significant effect on the observed relationship between level of internet addiction and depression.

Matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) in preoperative serum as independent prognostic markers in patients with colorectal cancer.

Colorectal cancer is one of the leading causes of cancer related death in developed countries. One of the reasons is the absence of tumor specific diagnostic and prognostic markers. The aim of this study was to examine the correlation of matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) expressions in serum and clinicopathological features of the colorectal adenocarcinoma. Another aim was to examine expression of MMP-9 in the tissue of the colorectal carcinoma in MMP-9 serum positive patients. In addition, we tried to establish the correlation between preoperative levels of serum markers (CEA and CA 19-9) and presence of MMP-2 or MMP-9. The study was performed on 32 patients with colorectal adenocarcinoma who underwent surgery and 11 patients in a control group who were operated for benign diseases. The samples were analyzed by SDS-PAGE to determine the molecular mass and SDS-PAGE zymography to determine levels of MMP-2 and MMP-9. Expression of MMP-9 was determined immunohistochemically in the tissue of the colorectal carcinoma of MMP-9 serum positive patients. MMP-2 and MMP-9 levels were increased in the serum of the patients with colorectal cancer compared to the control group. There was significant correlation in MMPs levels among the patients with tumor stage I and II and the patients with tumor stage III and IV. Obtained results did not demonstrate correlation between levels of CEA, CA 19-9 and presence of MMP-2 or MMP-9. MMP-9 expression was positive in 85% of MMP-9 serum positive patients with colorectal carcinoma. The overexpression of MMP-2 and MMP-9 strongly suggests its association with colorectal adenocarcinoma. Detection of MMP-2 and MMP-9 in serum might be useful for identification of patients with higher risk for colorectal cancer recurrence.

Volumetric Analysis of Amygdala, Hippocampus, and Prefrontal Cortex in Therapy-Naive PTSD Participants

Objective. In our study we have hypothesized that volume changes of amygdala, hippocampus, and prefrontal cortex are more pronounced in male posttraumatic stress disorder participants. Material and Methods. We have conducted a study of 79 male participants who underwent MRI brain scanning. PTSD diagnosis was confirmed in 49 participants. After MRI was taken all scans were software based volume computed and statistically processed. Results. We found that left amygdala is the most significant parameter for distinction between PTSD participants and participants without PTSD. There were no significant differences in volumes of hippocampi and prefrontal cortices. Roc curve method outlined left amygdala AUC = 0.898 (95% CI = 0.830–0.967) and right amygdala AUC = 0.882 (95% CI = 0.810–0.954) in the group of PTSD participants which makes both variables highly statistically significant. Conclusion. The present investigation revealed significant volume decrease of left amygdala in PTSD patients. Concerning important functions of the amygdala and her neuroanatomical connections with other brain structures, we need to increase number of participants to clarify the correlation between impared amygdala and possible other different brain structures in participants with PTSD.

On Modified Gravity

We consider some aspects of nonlocal modified gravity, where nonlocality is of the type \(R\mathcal{F}(\square )R\). In particular, using Ansatz of the form \( \square R = cR^{\gamma}, \) we find a few special cosmological solutions for the spatially flat FLRW metric. There are singular and nonsingular bounce solutions. For late cosmic time, scalar curvature R(t) is in low regime and scale factor a(t) is decelerated.

Microsatellite instability affecting the T17 repeats in intron 8 of HSP110, as well as five mononucleotide repeats in patients with colorectal carcinoma.

AIM To investigate mononucleotide markers: BAT-25, BAT-26, NR-21, NR-22 and NR-24 in patients with colorectal cancer (CRC), and the status of HSP110T17, KRAS, BRAF and the MLH1 promoter mutations in microsatellite unstable CRC. METHODS Genetic assessments were performed on samples obtained following resection of CRC in 200 patients. RESULTS Allelic variations of HSP110T17 were found in all 18 patients with microsatellite instabilities (MSIs) in at least three markers (high-frequency MSI). By contrast, mutations of HSP110T17 were absent in all 20 patients with no MSI frequency. Eight out of 182 patients with low (instability in one marker) or no frequency MSI had allelic shifts due to polymorphisms of BAT-25 (1.5%), NR-21 (1.75%) and NR-24 (1.5%). BRAF mutations were associated with >5 bp shortening of HSP110T17. CONCLUSION Patients with high-frequency MSI CRC had allelic variations of HSP110T17. BRAF mutations occur along with greater shortening in HSP110T17 during oncogenesis via the MSI pathway.

Clinical and pathological tools for identifying microsatellite instability in colorectal cancer

Aim To assess practical accuracy of revised Bethesda criteria (BGrev), pathological predictive model (MsPath), and histopathological parameters for detection of high-frequency of microsatellite instability (MSI-H) phenotype in patients with colorectal carcinoma (CRC). Method Tumors from 150 patients with CRC were analyzed for MSI using a fluorescence-based pentaplex polymerase chain reaction technique. For all patients, we evaluated age, sex, family history of cancer, localization, tumor differentiation, mucin production, lymphocytic infiltration (TIL), and Union for International Cancer Control stage. Patients were classified according to the BGrev, and the groups were compared. The utility of the BGrev, MsPath, and clinical and histopathological parameters for predicting microsatellite tumor status were assessed by univariate logistic regression analysis and by calculating the sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values. Results Fifteen out of 45 patients who met and 4 of 105 patients who did not meet the BGrev criteria had MSI-H CRC. Sensitivity, specificity, PPV, and NPV for BGrev were 78.9%, 77%, 30%, and 70%, respectively. MSI histology (the third BGrev criterion without age limit) was as sensitive as BGrev, but more specific. MsPath model was more sensitive than BGrev (86%), with similar specificity. Any BGrev criterion fulfillment, mucinous differentiation, and right-sided CRC were singled out as independent factors to identify MSI-H colorectal cancer. Conclusion The BGrev, MsPath model, and MSI histology are useful tools for selecting patients for MSI testing.

Fibroepithelial polyp of the upper third of ureter.

A fibroepithelial polyp is an unusual benign tumour of the ureter. Clinically, it presents with symptoms secondary to obstruction.1–3 In children, the probability of making the correct diagnosis preoperatively is low (20%).4 In recently published papers on adults, ureteric fibroepithelial polyp excision is usually accomplished through ureteroscopy.5 In children, treatment usually involves an open surgical procedure.4 A 10-year-old boy presented for evaluation of left side flank pain. The patient had similar symptoms a few times over the preceding 10months. Urine analysis showed microscopic haematuria. Urinary culture was negative, and complete blood count and blood chemistry were normal. Ultrasonography showed left side hydronephrosis. A plain abdominal X-ray showed no calculi. Intravenous pyelography confirmed left side hydronephrosis, with dilatation of the upper third of ureter. Ureteroscopy showed that the ureteral lumen was occupied by a tumourous mass. The polyp could not be excised endoscopically because it completely obstructed the lumen. The site of the obstruction was found by open surgery (assisted by ureteroscopic light directed retrogradely) on the border between the upper and the medial ureteric third. The ureter was opened, and the polyp removed. The site of the attachment of the polyp required a shunt segment of the ureter to be removed, and a wide anastomosis was made. The ureteric stent was inserted and removed after a month. Histological examination of the specimen confirmed that it was a fibroepithelial polyp. There were no perioperative complications, and the child was discharged after 3 days. At 3 years after surgery, the patient remained well. Follow-up ultrasonography confirmed the resolution of hydroureteronephrosis. The child’s family was offered psychological counseling and support by a pyschiatrist in order to overcome their concerns regarding the outcome of the procedure and the wellbeing of the child. Tumours of the ureter are extremely rare in children. A ureteric fibroepithelial polyp is a tumour of a mesodermal origin and comprises 20% of all ureteric tumors.1 In the paediatric population, the majority occur in the posterior urethra, but if the ureter is involved, it is usually in its upper part, and predominantly in boys. The polyp has a fibrovascular core covered with normal transitional epithelial cells. Macroscopically, it resembles a tree branch. The aetiology of ureteric fibroepithelial polyp is unknown, despite various speculations – chronic irritation, infection, hormonal imbalance, allergy and developmental defects.2 Intermittent flank pain and haematuria (micro and macro) are dominant in clinical presentation. Preoperative diagnosis of ureteric tumour is difficult. In these patients, ultrasonography shows dilatation of the pyelocalyceal system of the kidney and a part of the ureter. IVP is a more sensitive means in the diagnosis of ureteric polyp over ultrasonography or a nuclear medicine renal excretory study (up-to-date methods for the diagnosis of pelviureteric junction (PUJ) obstruction).4 Differentiating the ureteral polyp from other causes of PUJ or ureteric obstruction may require retrograde pyelography or ureteroscopy. Although ureteric malignancy in children is extremely rare, histopathological evaluation (a ureteroscopic cold-cup punch biopsy or open surgical ‘ex tempore’ biopsy) is imperative before definitive treatment. The best treatment of ureteric fibroepithelial polyps in adults is polypectomy by ureteroscopy (before which ‘thinking about it cause of obstruction’ is required, as well as the availability of adequate devices and a skilful ureteroscopist). Ureteroscopic treatment of ureteric fibroepithelial polyp in children is infrequent4; open surgical management has been standard (with dismembered pyeloplasty or reanastomosis of the ureter), perhaps because of difficulties making a correct preoperative diagnosis In our patient, we used ureteroscopic light to identify the level of ureteric obstruction. We did not continue with ureteroscopic excision because this large polyp completely obstructed the ureter and had a wide base. Open surgical method allowed a total excision of the polyp. In atypical hydronephrosis and dilatation of the ureter, the diagnosis of fibroepithelial polyp should be considered. Ureteroscopy is useful to confirm and localize the polyp. In children, open surgery is used frequently to confirm and to remove the polyp. Such an approach seems justifiable and acceptable.

Cosmological solutions in modified gravity with monomial nonlocality

We consider cosmological properties of modified gravity with nonlocal term R p F ( ? ) R q in its Lagrangian. Equations of motion are presented. For the flat FLRW metric, and some particular values of natural numbers p and q cosmological solutions of the form a ( t ) = C e - γ 12 t 2 are found.

Constant curvature cosmological solutions in nonlocal gravity

Modified gravity model with nonlocal term of the form R−1F(□)R is considered. Cosmological solutions for constant scalar curvature are found for all three values of curvature constant k = 0, ±1. Among these solutions there are two nonsingular bounce solutions and one singular cyclic cosmic solution.

Some Power-Law Cosmological Solutions in Nonlocal Modified Gravity

Modified gravity with nonlocal term \(R^{-1}\mathcal{F}(\square )R,\) and without matter, is considered from the cosmological point of view. Equations of motion are derived. Cosmological solutions of the form \(a(t) = a_{0}\vert t - t_{0}\vert ^{\alpha },\) for the FLRW metric and k = 0, ±1, are found.