Edge- and Node-Disjoint Paths in P Systems

In this paper, we continue our development of algorithms used for topological network discovery. We present native P system versions of two fundamental problems in graph theory: finding the maximum number of edge- and node-disjoint paths between a source node and target node. We start from the standard depth-first-search maximum flow algorithms, but our approach is totally distributed, when initially no structural information is available and each P system cell has to even learn its immediate neighbors. For the node-disjoint version, our P system rules are designed to enforce node weight capacities (of one), in addition to edge capacities (of one), which are not readily available in the standard network flow algorithms.Comment: In Proceedings MeCBIC 2010, arXiv:1011.005

On acceptance conditions for membrane systems: characterisations of L and NL

In this paper we investigate the affect of various acceptance conditions on recogniser membrane systems without dissolution. We demonstrate that two particular acceptance conditions (one easier to program, the other easier to prove correctness) both characterise the same complexity class, NL. We also find that by restricting the acceptance conditions we obtain a characterisation of L. We obtain these results by investigating the connectivity properties of dependency graphs that model membrane system computations

The Role of Occlusion of the External Ear Canal in Hearing Loss

Objective:The objectives are to determine and compare the degrees of hearing loss upon occlusion of the cartilaginous and the bony portion of the external ear canal (EAC).Methods:There were 20 healthy participants with normal ears, and all gave an informed consent. After an otoscopy, a baseline pure tone audiogram (PTA) was conducted. If the PTA of the participant was normal, aqueous cream was applied with a syringe via an 18 G cannula, from the tympanic membrane up to the isthmus which corresponds to the bony ear canal. A second PTA was conducted, and subsequently the cream was removed via suction under microscope guidance. The procedure was then repeated with the cream applied from the isthmus to the aperture of the external ear canal using the same cannula followed by a PTA and removal of cream under microscope.Results:The mean threshold difference of occlusion at both portions of the ear canal were compared and analyzed. The mean threshold difference of hearing loss upon occlusion at the cartilaginous EAC was 37.5 to 48 dB. The mean threshold difference of hearing loss upon occlusion at the bony EAC was less, with a range of 21 to 24.95dB. There was a statistical difference (p<0.05) in the hearing loss between the blockage of the cartilaginous canal versus the blockage of the bony canal with a maximum difference at 2kHz.Conclusion:Cartilaginous block of the external ear canal causes more hearing loss than block of the bony ear canal. This correlates with the concept and properties of sound waves, resonance and impedance

Significance of Targeting RNA Polymerase I in Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (IHCC) is a much-overlooked cancer with a mortality rate that has increased throughout recent years, as stated by the American Cancer Society [1]. In the United States alone, there are an estimated 8,000 adults being diagnosed with IHCC every year, with a five-year survival rate of 9% [2]. Chemotherapy options for the treatment of IHCC include systemic chemotherapy such as gemcitabine, capecitabine, and oxaliplatin. These medications carry a wide array of adverse factors that may warrant discontinuation due to the detriment to the well-being of the patient. Additionally, a broad field of therapy that may also be used, even throughout many other types of cancers, is aimed to arm the immune system, such as targeted therapy as well as immunotherapy. Even with the consideration of these options, we cannot say that our issue has been solved. If the cancer is diagnosed at an early stage and treated adequately, the five-year survival rate is still at 24% [2], which will still result in the mortality of majority of the individuals with IHCC. Therefore, the discovery of new potential molecular targets is required which could be used in rationale designing of the prevention and treatment strategies against advanced IHCC. The ribosome biogenesis process is dysregulated in most cancer cells because of the high demand of protein synthesis. However, the role of ribosome biogenesis components was the least studied in cancer settings. From our extensive research in various systems, we found that POLR1A (RPA194), a catalytic subunit of RNA polymerase I, is significantly overexpressed (

Using illness scripts to teach clinical reasoning skills to medical students

Background and Objectives: Most medical students learn clinical reasoning skills informally during clinical rotations that have varying quality of supervision. We conducted a randomized controlled trial to determine if a workshop that uses "illness scripts" could improve students' clinical reasoning skills when making diagnoses of patients portrayed in written scenarios. Methods: In 2007-2008, 53 fourth-year medical students were randomly assigned to either a family medicine (intervention) or psychiatry (control) clerkship at The Chinese University of Hong Kong. Students in the intervention group participated in a 3-hour workshop on clinical reasoning that used illness scripts. The workshop was conducted with small-group teaching using a Web-based set of clinical reasoning problems, individualized feedback, and demonstration of tutors' reasoning aloud. The effectiveness of the intervention was assessed using the Diagnostic Thinking Inventory (DTI) and the measurement of individual students' performance in solving clinical reasoning problems (CRP). Results: The postintervention overall DTI scores between groups were similar (mean difference 0, 95% confidence interval [CI]= -7.4 to 7.4). However, the total scores on the CRP assessment were 14% (95% CI=8% to 21%) higher in the intervention group than in controls. Conclusion: A workshop on illness scripts may have some benefit for improving diagnostic performance in clinical reasoning problems.link_to_OA_fulltex

Honey targets ribosome biogenesis process in human pancreatic cancer cells to inhibit their growth and metastatic phenotypes

Background: Pancreatic cancer (PanCa) is the fourth deadliest cancer worldwide and is expected to become the second deadliest cancer by 2030. In the USA, the National Cancer Institute put forth a grim prediction stating that there will be 64,050 new cases in 2023 alone and about 50,000 of these patients will die. Existing therapeutic regimens against PanCa are not that effective and show unacceptable toxicities. Therefore, developing highly effective new agents with less toxicity is urgently required, which could be used as a monotherapy or as an adjuvant to treat PanCa patients. Honey is known for its tremendous health benefits and has been used in various traditional medicines. Several studies have defined honey to be cardioprotective, neuroprotective, ant-inflammatory, and immunomodulatory. In addition to these advantages, honey also possesses anti-cancer properties. However, no study has explored its effect against PanCa. In this study, we evaluated the anti-cancer potential of honey and its molecular mechanisms against PanCa. Methods: MTT assay and colony formation assays were performed to determine the effect of honey on proliferation of human PanCa cells (AsPc-1 and MiaPaCa-2). Wound healing assay was performed to evaluate the antimigratory potential of honey against PanCa cells. Western blot and qPCR assays were performed to determine the effect of honey on the regulation of ribosome biogenesis, cell proliferation, and apoptosis in PanCa cells. Results: Ribosome biogenesis is dysregulated in most cancer types, which results in aggressive metastatic phenotypes seen in cancer cells. We observed that the transcription factor UBTF and other ribosome biogenesis components were aberrantly overexpressed in pancreatic tumor tissues as compared to normal pancreatic tissues. These associations are linked to aggressive phenotypes seen in PanCa cells. Interestingly, we observed that honey treatment significantly suppressed ribosome biogenesis in PanCa cells as observed by significant decrease in UBTF and 5’-ETS expression. Honey treatment markedly inhibited the expression of RPA194, a catalytic unit of RNA polymerase I, and nucleolin in both AsPC-1 and MiaPaCa-2 cells. MTT analysis indicated that honey exerted dose-dependent cellular cytotoxicity in AsPc-1 and MiaPaCa-2 cells, with IC50 values 45.2 and 30.3 mg/ml, respectively. In addition to its potential cytotoxicity, honey treatment clearly interfered with the wound healing and clonogenic ability of these PanCa cells as demonstrated by wound healing and colony formation assays. We also observed that honey treatment induced apoptosis in AsPC-1 and MiaPaCa-2 cells, which was confirmed by the the increase of the population of Annexin V positive cells and cleavage of PARP protein. A decrease in expression of Bcl-2 and p53 (truncated in AsPc-1 and mutated in MiaPaCa-2) also indicated that these cancer cells were undergoing apoptosis. Conclusions: Overall, our results demonstrated for the first time that honey has potential to induce apoptosis and prevent pancreatic cancer cell growth through modulation of ribosome biogenesis process. It implies that honey could be used as a natural remedy to prevent human pancreatic cancer and utilized as an adjuvant in ongoing chemo/-immunotherapy regimens. Further detailed studies using appropriate pre-clinical mouse models of PanCa will be warranted to establish its anti-cancer potential for the treatment of PanCa

Evolução do saco aneurismático após a exclusão cirúrgica dos aneurismas de artéria poplítea

Popliteal artery aneurysms are frequent and may lead to thromboembolic events and limb loss. PURPOSE: To evaluate clinical and ultrasonographic follow-up of patients who underwent exclusion of a popliteal artery aneurysm using the technique proposed by Edwards. METHODS: Data of all patients who underwent surgery to repair a popliteal artery aneurysm at Hospital das Clinicas, the São Paulo University Medical School between 1996 and 2004 were reviewed. Inclusion criteria were repair with aneurysm exclusion and bypass using the technique proposed by Edwards, as well as the existence of preoperative and postoperative measurements of the aneurysmal sac. RESULTS: Data of 16 patients who underwent 20 procedures for popliteal artery aneurysm exclusion and bypass were available to analysis. The preoperative diameter of the popliteal artery aneurysms ranged from 1.3 cm to 6.1 cm (mean = 3.1 cm). Patients underwent duplex ultrasound scanning 1 month to 7 years after surgical repair. Follow-up of the 20 cases revealed that 10 aneurysms exhibited decreased mean transverse diameters, ranging from 0.2 to 2.3 cm, while 7 had increased in diameter, ranging 0.3 to 3.3 cm, and 3 remained unchanged. Flow was observed only in 5 outo f the 20 procedures, 3 of which (60%) had increased diameters. CONCLUSION: Although exclusion is a widely accepted procedure for the repair of popliteal artery aneurysms, data in the literature and the results of this study, which did not include cases of rupture or compression, suggest that strict follow-up of patients who undergo aneurysm exclusion is necessary.Os aneurismas da artéria poplítea são freqüentes e estão associados a eventos trombo-embólicos que podem acarretar isquemia grave com risco de perda da extremidade inferior acometida. OBJETIVO: Avaliar a evolução clínica dos pacientes e ultra-sonográfica dos aneurismas de artéria poplítea excluídos pela técnica de Edwards. MÉTODO: Análise retrospectiva dos pacientes com diagnóstico de aneurisma da artéria poplítea operados no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, no período compreendido entre os anos de 1996 a 2004. Foram incluídos os pacientes submetidos à exclusão do aneurisma pela técnica de Edwards e que possuíam diâmetro transverso máximo do aneurisma mensurado no período pré e pós-operatório. RESULTADOS: Dezesseis pacientes foram submetidos a correção cirúrgica de 20 aneurismas. O diâmetro do aneurisma no período pré-operatório variou entre 1,3 cm a 6,1 cm (média 3,1cm). O controle ultrasonográfico foi realizado em intervalo de 1 mês a 7 anos do procedimento cirúrgico. Houve diminuição do diâmetro do aneurisma de artéria poplítea em 10/20 extremidades (variação de 0,2 cm a 2,3 cm), aumento em 7/20 (variação de 0,3 cm a 3,3 cm) e estabilidade em 3/20. Observou-se a ocorrência de fluxo no saco aneurismático em 5 dentre os 20 procedimentos. Destes, três apresentaram crescimento do mesmo (60% dos casos com fluxo). CONCLUSÃO: Esta amostra de pacientes, sem rotura ou sinais e sintomas de compressão, associada à análise da literatura, demonstra que o seguimento estreito do aneurisma excluído é necessário