1591. The Sierpiński product of graphsJurij Kovič, Tomaž Pisanski, Sara Sabrina Zemljič, Arjana Žitnik, 2023, original scientific article Abstract: In this paper we introduce a product-like operation that generalizes the construction of the generalized Sierpiński graphs. Let $G$, $H$ be graphs and let $f: V(G) \to V(H)$ be a function. Then the Sierpiński product of graphs $G$ and $H$ with respect to $f$, denoted by $G\otimes_f H$, is defined as the graph on the vertex set $V(G) \times V(H)$, consisting of $|V(G)|$ copies of $H$; for every edge $\{g, g'\}$ of $G$ there is an edge between copies $gH$ and $g'H$ of form $\{(g, f(g'), (g', f(g))\}$. Some basic properties of the Sierpiński product are presented. In particular, we show that the graph $G\otimes_f H$ is connected if and only if both graphs $G$ and $H$ are connected and we present some conditions that $G, \, H$ must fulfill for $G\otimes_f H$ to be planar. As for symmetry properties, we show which automorphisms of $G$ and $H$ extend to automorphisms of $G\otimes_f H$. In several cases we can also describe the whole automorphism group of the graph $G\otimes_f H$. Finally, we show how to extend the Sierpiński product to multiple factors in a natural way. By applying this operation $n$ times to the same graph we obtain an alternative approach to the well-known $n$-th generalized Sierpiński graph. Keywords: Sierpiński graphs, graph products, connectivity, planarity, symmetry Published in DiRROS: 19.03.2024; Views: 446; Downloads: 337
Full text (533,30 KB) This document has many files! More... |
1592. |
1593. On metric dimensions of hypercubesAleksander Kelenc, Aoden Teo Masa Toshi, Riste Škrekovski, Ismael G. Yero, 2023, original scientific article Abstract: In this note we show two unexpected results concerning the metric, the edge metric and the mixed metric dimensions of hypercube graphs. First, we show that the metric and the edge metric dimensions of $Q_d$ differ by at most one for every integer $d$. In particular, if $d$ is odd, then the metric and the edge metric dimensions of $Q_d$ are equal. Second, we prove that the metric and the mixed metric dimensions of the hypercube $Q_d$ are equal for every $d \ge 3$. We conclude the paper by conjecturing that all these three types of metric dimensions of $Q_d$ are equal when d is large enough. Keywords: edge metric dimension, mixed metric dimension, metric dimension, hypercubes Published in DiRROS: 19.03.2024; Views: 366; Downloads: 74
Full text (259,98 KB) |
1594. Brain meningioma invading and destructing the skull bone : replacement of the missing bone in vivoTomaž Velnar, Rado Pregelj, Clara Limbaeck Stanic, 2011, original scientific article Abstract: Background. Meningiomas are frequently encountered tumours. In those invading locally into the adjacent tissue, reconstructions may pose a problem. Case report. We report a case of a benign convexity brain meningioma with invasion into the skull bone and subcutaneous tissue. The tumour was removed completely, together with the infiltrated tissue and the defects were successfully closed with in vivo bone reconstruction. Conclusions. The reconstruction of the skull bone is sometimes needed after the benign meningioma excision. Artificial bone may be a suitable material, allowing fastintraoperative reconstruction with excellent brain protection andcosmetic effect during the one-stage procedure. Published in DiRROS: 19.03.2024; Views: 251; Downloads: 142
Full text (685,53 KB) This document has many files! More... |
1595. |
1596. New developments in surgery of malignant gliomasAndrej Vranič, 2011, review article Abstract: Background. Malignant gliomas account for a high proportion of brain tumours. With new advances in neurooncology, the recurrence-free survival of patients with malignant gliomas has been substantially prolonged. It, however, remains dependent on the thoroughness of the surgical resection. The maximal tumour resection without additional postoperative deficit is the goal of surgery on patients with malignant gliomas. In order to minimize postoperative deficit, several pre- and intraoperative techniques have been developed. Conclusions. Several techniques used in malignant glioma surgery have been developed, including microsurgery, neuroendoscopy, stereotactic biopsy and brachytherapy.Imaging and functional techniques allowing for safer tumour resection have a special value. Imaging techniques allow for better preoperative visualization and choice of the approach, while functional techniques help us locate eloquent regions of the brain. Published in DiRROS: 19.03.2024; Views: 290; Downloads: 90
Full text (669,85 KB) |
1597. CD133/prominin1 is prognostic for GBM patient's survival, but inversely correlated with cysteine cathepsine' expression in gliobastoma derived spheroidsSeyed Yousef Ardebili, Irena Zajc, Boris Gole, Benito Campos, Christel Herold-Mende, Sara Drmota Prebil, Tamara Lah Turnšek, 2011, original scientific article Abstract: Introduction. CD133 is a marker for a population of glioblastoma (GBM) and normal neural stem cells (NNSC). We aimed to reveal whether the migratory potential and differentiation of these stem cells is associated with CD133 expression and with cathepsin proteases (Cats). Materials and methods. The invasiveness of normal NNSC, GBM/CD133+ cell lines and GBM spheroids was evaluated in 3D collagen, as well as of U87-MG and normal astrocytes (NHA) grown in monolayers in 2D Matrigel. Expression of Cats B, L and S was measuredat mRNA and activity levels and their relation to invasiveness, to CD133 mRNA in 26 gliomas, and to the survival of these patients. Results. The average yield of CD133+ cells from GBM samples was 9.6%. Survival of patients with higher CD133 mRNA expression was significantly shorter (p< 0.005). Invasion, associated with proteolytic degradation of matrix, was higher in normal stem cells and GBM spheroids and cells than in isolated GBM CD133+ cells. In glioma samples, there was no correlation between CD133 mRNA expression and Cat mRNAs, but there was an inverse correlation with Cat activities. Conclusions. The study confirms CD133 as a prognostic marker for the survival of GBM patients. We demonstrated that NNSC have higher invasion potential and invade the collagen matrix in a mode different from that of GBM,initiating stem cell spheres. This result could have implications for the design of new therapeutics, including protease inhibitors that specifically target invasive tumour stem cells. Increased activity of cathepsins in CD133- cells suggests their role in the invasive behaviour of GBM. Published in DiRROS: 19.03.2024; Views: 331; Downloads: 95
Full text (1,00 MB) |
1598. Microsatellite instability in colorectal cancerMatej Horvat, Borut Štabuc, 2011, review article Abstract: Background. Colorectal cancer (CRC) is the third most common cancer in the world. In 75% CRC develops sporadically, in 25% hereditary or as a consequenceof inflammatory bowel disease. CRC carcinogenesis develops over many years. The cause of CRC in 85% is chromosomal instability (CIN) and in 15% microsatellite instability (MSI-H), where hereditary nonpolyposis colorectal cancer (HNPCC) represents 10-20%. Microsatellite sequences (MS) arerepeated sequences of short stretches of DNA all over the genome. Microsatellite stability (MSS) means MS are the same in each cell of an individual, whereas microsatellite instability (MSI-H) means MS differ in normal and cancer cells of an individual. The cause of MSI-H is a damaged mismatch repair mechanism (MMR), with the most important MMR proteins being MSH2, MLH1 and MSH6. Conclusions. MSI-H seems to be an important prognostic factor in CRC and an important predictive factor of CRC chemotherapeutic treatment efficacy. Clinical trials conducted until now have shown contradictory findings in different chemotherapeutic settings, adjuvant and palliative; therefore MSI-H is going to be the object of the future research. The future of cancer treatment is in the individualized therapy based on molecular characteristics of the tumour, such as MSI-H in CRC. Published in DiRROS: 19.03.2024; Views: 336; Downloads: 156
Full text (489,56 KB) This document has many files! More... |
1599. Triple negative breast cancer : prognostic factors and survivalTanja Ovčariček, Snježana Frković-Grazio, Erika Matos, Barbara Možina, Simona Borštnar, 2011, original scientific article Abstract: Background. Triple negative breast cancer (TNBC) is defined by a lack of expression of both estrogen (ER) and progesteron(PgR) receptors as well as human epidermal growth factor receptor 2 (HER2). Our retrospective analysis addressed prognostic factors for short- and long-term outcomes of patients (pts) with TNBC pts treated in routine clinical practice. Patient and methods.Our retrospective study included 269 TNBC treated at Institute of Oncology Ljubljana between March 2000 and December 2006. The collected data included patientsć, tumoursć and treatmentsć characteristics. The survival analyses were performed using the Kaplan-Meier method. The Cox proportional hazard model was used in the multivariate analysis. Results. The median age ofour patients was 55.3 yrs (23-88.5) and the median follow-up was 5.9 yrs (0.3-9.6). Six (2%) pts experienced local only, 79 (92%) pts distal recurrenceand 66 (24%) died. The predominant localisation of the first relapsewas in visceral organs (70.4%). The 5-year disease-free survival (DFS) for the entire group was 68.2% and the 5-year overall survival (OS) was 74.5%.We found a pattern of high recurrence rate in the first 3 years following the diagnosis and a clear decline in recurrence rate over the next 3years. In the univariate analysis age, nodal status, size and lymphovascular invasion (LVI) were found to have a significant impact on DFS as well as on OS. In the multivariate analysis only age (HR=1.79; 95%CI=1.14-2.82; p=0.012) and nodal status (HR=2.71; 95%CI=1.64-4.46; p<0.001) retained their independent prognostic value for DFS and for OS only the nodal status (HR=2.96; 95%CI=1.51-5.82; p=0.002). (Abstract truncated at 2000 characters) Published in DiRROS: 19.03.2024; Views: 272; Downloads: 110
Full text (536,99 KB) |
1600. Image cytometric nuclear texture features in inoperable head and neck cancer : a pilot studyMargareta Strojan Fležar, Jaka Lavrenčak, Mario Žganec, Primož Strojan, 2011, original scientific article Abstract: Background. Image cytometry can measure numerous nuclear features which could be considered a surrogate end-point marker of molecular genetic changes in a nucleus. The aim of the study was to analyze image cytometric nuclear featuresin paired samples of primary tumor and neck metastasis in patients with inoperable carcinoma of the head and neck. Materials and methods. Image cytometric analysis of cell suspensions prepared from primary tumor tissue andfine needle aspiration biopsy cell samples of neck metastases from 21 patients treated with concomitant radiochemotherapy was performed. Nuclear features were correlated with clinical characteristics and response to therapy. Results. Manifestation of distant metastases and new primaries was associated (p<0.05) with several chromatin characteristics from primary tumor cells, whereas the origin of index cancer and disease response in the neck wasrelated to those in the cells from metastases. Many nuclear features of primary tumors and metastases correlated with the TNM stage. Conclusions. A specific pattern of correlation between well-established prognostic indicatorsand nuclear features of samples from primary tumors and those from neck metastases was observed. Image cytometric nuclear features represent a promising candidate marker for recognition of biologically different tumor subgroups. Published in DiRROS: 19.03.2024; Views: 282; Downloads: 81
Full text (427,02 KB) |