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Search Results: 1 - 10 of 24 matches for " Venizelos "
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Intestinal cytochromes P450 regulating the intestinal microbiota and its probiotic profile
Eugenia Elefterios Venizelos Bezirtzoglou
Microbial Ecology in Health and Disease , 2012, DOI: 10.3402/mehd.v23i0.18370
Abstract: Cytochromes P450 (CYPs) enzymes metabolize a large variety of xenobiotic substances. In this vein, a plethora of studies were conducted to investigate their role, as cytochromes are located in both liver and intestinal tissues. The P450 profile of the human intestine has not been fully characterized. Human intestine serves primarily as an absorptive organ for nutrients, although it has also the ability to metabolize drugs. CYPs are responsible for the majority of phase I drug metabolism reactions. CYP3A represents the major intestinal CYP (80%) followed by CYP2C9. CYP1A is expressed at high level in the duodenum, together with less abundant levels of CYP2C8-10 and CYP2D6. Cytochromes present a genetic polymorphism intra- or interindividual and intra- or interethnic. Changes in the pharmacokinetic profile of the drug are associated with increased toxicity due to reduced metabolism, altered efficacy of the drug, increased production of toxic metabolites, and adverse drug interaction. The high metabolic capacity of the intestinal flora is due to its enormous pool of enzymes, which catalyzes reactions in phase I and phase II drug metabolism. Compromised intestinal barrier conditions, when rupture of the intestinal integrity occurs, could increase passive paracellular absorption. It is clear that high microbial intestinal charge following intestinal disturbances, ageing, environment, or food-associated ailments leads to the microbial metabolism of a drug before absorption. The effect of certain bacteria having a benefic action on the intestinal ecosystem has been largely discussed during the past few years by many authors. The aim of the probiotic approach is to repair the deficiencies in the gut flora and establish a protective effect. There is a tentative multifactorial association of the CYP (P450) cytochrome role in the different diseases states, environmental toxic effects or chemical exposures and nutritional status.
Language Impairment and Right Hemiparesis in a 54-Year-Old Woman
Alexander Venizelos,José Biller
Frontiers in Neurology , 2011, DOI: 10.3389/fneur.2011.00040
Abstract: A 54-year-old woman presented to the emergency room with 3 months of slurred speech, language problems, and right hemiparesis. Initial impression based on history, exam, and imaging was brain abscess vs. primary or metastatic neoplasm. Brain biopsy of the lesion and pathologic specimens were obtained. Below is a description of her presentation, hospital course, imaging, and pathology, as well as a short discussion of the final diagnosis.
Neutrophil Elastase Enhances Sputum Solubilization in Cystic Fibrosis Patients Receiving DNase Therapy
Venizelos Papayannopoulos,Doris Staab,Arturo Zychlinsky
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0028526
Abstract: Cystic fibrosis patients suffer from chronic lung infection and inflammation due to the secretion of viscous sputum. Sputum viscosity is caused by extracellular DNA, some of which originates from the release of neutrophil extracellular traps (NETs). During NET formation neutrophil elastase (NE) partially processes histones to decondense chromatin. NE is abundant in CF sputum and is thought to contribute to tissue damage. Exogenous nucleases are a palliative treatment in CF as they promote sputum solubilization. We show that in a process reminiscent of NET formation, NE enhances sputum solubilization by cleaving histones to enhance the access of exogenous nucleases to DNA. In addition, we find that in Cf sputum NE is predominantly bound to DNA, which is known to downregulate its proteolytic activity and may restrict host tissue damage. The beneficial role of NE in CF sputum solubilization may have important implications for the development of CF therapies targeting NE.
A patient with amyotrophic lateral sclerosis and atypical clinical and electrodiagnostic features: a case report
Alexander Venizelos, Youngsook Park, Morris A Fisher
Journal of Medical Case Reports , 2011, DOI: 10.1186/1752-1947-5-538
Abstract: We present the case of a 57-year-old Caucasian man with pathological findings on postmortem examination consistent with amyotrophic lateral sclerosis but atypical clinical and electrodiagnostic features. He died after a rapid course of progressive weakness. The patient did not respond to immunosuppressive therapy.Amyotrophic lateral sclerosis should be considered in patients with a rapidly progressive, unexplained neuropathic process. This should be true even if there are atypical clinical and electrodiagnostic findings. Absence of response to therapy and the development of upper motor neuron signs should reinforce the possibility that amyotrophic lateral sclerosis may be present. Since amyotrophic lateral sclerosis is a fatal illness, however, the possibility of this disease in patients with atypical clinical features should not diminish the need for a thorough diagnostic evaluation and treatment trials.Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by anterior horn cell and corticospinal degeneration, primarily involving motor neurons in the cerebral cortex, brainstem, and spinal cord. Despite its recognition for over 140 years, ALS remains a poorly understood, usually rapidly progressive and fatal disease. More than 60% of patients with ALS die within three years [1]. Riluzole is the only recognized medication treatment and its effect is modest, prolonging life for only two to three months [2]. Given this, an accurate diagnosis is critical. A primary responsibility for the physician caring for patients with ALS is considering other potentially treatable illnesses including an acquired neuropathy.Although criteria are available for diagnosing ALS [3,4], the diagnosis may be difficult given the variability of clinical findings and absence of a biological marker. The importance of electrodiagnostic studies in making a diagnosis of ALS has recently been emphasized [3]. We describe he case of a patient who had clinical an
Normal development of fetal hepatic haematopoiesis during the second trimester of gestation is upregulated by fibronectin expression in the stromal cells of the portal triads
Tamiolakis,D.; Venizelos,I.; Nikolaidou,S.; Jivanakis,T.;
Revista Espa?ola de Enfermedades Digestivas , 2007, DOI: 10.4321/S1130-01082007001000003
Abstract: objective: in midtrimester fetuses the principal site of hematopoiesis is the liver. in hematopoietic organs, stromal cells such as fibroblasts, epithelial cells, and macrophage-like cells develop networks to maintain hematopoiesis, i.e. hematopoietic stem cell self-renewal, proliferation, and growth, by interaction with hematopoietic progenitor cells. ecm glycoproteins produced by the stromal cells are known to play a critical role in the regulation of cell growth and differentiation. numerous soluble and membrane-bound factors directly regulating haematopoiesis have been documented, but little is known about fetal hepatic stromal cell activity and stromal extracellular matrix protein-fibronectin, on fetal hepatic haematopoiesis. the binding of late stage erythroid cells to fibronectin has been well characterized and is believed to be critical for the terminal stages of erythroid differentiation. the intention of this article is to determine the role of fibronectin in fetal hepatic hematopoietic proliferation and differentiation in different stages of development. material and method: we examined and compared the immunohistochemical expression of fibronectin in the hepatic stromal portal fields in the 1st, 2nd, and 3rd trimester of gestation respectively, in relation to the appearance of cd34 progenitor hematopoietic, stromal progenitor and vascular endothelial positive cells. results: our results demonstrated a quantitative difference in the second trimester of gestation concerning the expression of fibronectin in the connective tissue stroma of the hepatic portal fields over the equivalent expression of the protein in the first (p < 0.0001, t-test) and third trimester (p < 0.0001, t-test). similar changes in the above period were found concerning the expression of cd34 during the second trimester of gestation, over the first (p < 0.0001, t-test) and third trimesters (p < 0.0001, t-test), suggesting a direct involvement of fibronectin in the sustaining of hematopo
Tryptophan Transport in Human Fibroblast Cells— A Functional Characterization
Vumma Ravi, Johansson Jessica, Lewander Tommy and Venizelos Nikolaos
International Journal of Tryptophan Research , 2012, DOI: 10.4137/IJTR.S6913
Abstract: There are indications that serotonergic neurotransmission is disturbed in several psychiatric disorders. One explanation may be disturbed transport of tryptophan (precursor for serotonin synthesis) across cell membranes. Human fibroblast cells offer an advantageous model to study the transport of amino acids across cell membranes, since they are easy to propagate and the environmental factors can be controlled. The aim of this study was to functionally characterize tryptophan transport and to identify the main transporters of tryptophan in fibroblast cell lines from healthy controls. Tryptophan kinetic parameters (Vmax and Km) at low and high concentrations were measured in fibroblasts using the cluster tray method. Uptake of 3H (5)-L-tryptophan at different concentrations in the presence and absence of excess concentrations of inhibitors or combinations of inhibitors of amino acid transporters were also measured. Tryptophan transport at high concentration (0.5 mM) had low affinity and high Vmax and the LAT1 isoform of system-L was responsible for approximately 40% of the total uptake of tryptophan. In comparison, tryptophan transport at low concentration (50 nM) had higher affinity, lower Vmax and approximately 80% of tryptophan uptake was transported by system-L with LAT1 as the major isoform. The uptake of tryptophan at the low concentration was mainly sodium (Na+) dependent, while uptake at high substrate concentration was mainly Na+ independent. A series of different transporter inhibitors had varying inhibitory effects on tryptophan uptake. This study indicates that tryptophan is transported by multiple transporters that are active at different substrate concentrations in human fibroblast cells. The tryptophan transport trough system-L was mainly facilitated by the LAT1 isoform, at both low and high substrate concentrations of tryptophan.
"Induction of Thymic HLA-DR signaling with Alpha-smooth muscle Actin expression during the second and third trimesters of gestation "
Tamiolakis D,Venizelos J,Kotini A,Skafida P
Acta Medica Iranica , 2003,
Abstract: Less than 5% of prenatal thymoctes express HLA-DR before week 12 of gestation. However, the number of HLA-DR- positive cells increases during the late second and third trimesters of development. To determine the role of alpha-smooth muscle actin in fetal thymic HLA-DR signaling in different stages of development we examined and compared the immunohistochemical expression of alpha-smooth muscle actin in the myoid cells of the thymic medulla stroma in the 2 nd, and 3rd trimesters of gestation respectively, over the equivalent expression of the protein in the 1 st trimester, in relation with the appearance of HLA-DR-positive thymocytes. Our results demonstrated a quantitative difference in the second and third trimesters of development concerning the expression of alpha-smooth muscle actin in the stromal myoid cells of the thymic medulla over the equivalent expression of the protein in the first (P<0.0001, t-test). Similar changes in the above period wee found concerning the expression of HLA-DR over the first (P<0.0001, test), suggesting a direct involvement of alpha-smooth muscel acting in the sustainence of HLA-DR reactivity. Our data provide evidence that a contractile microfilament alpha-smooth muscle actin plays a pivotal role in HLA-DR expression, through interaction between medullary stromal cells and thymoctes.
Diffuse large B-cell lymphoma arising from a multicentric mixed variant of Castleman′s disease
Venizelos I,Tamiolakis D,Simopoulos C,Nikolaidou S
Indian Journal of Cancer , 2004,
Abstract: This case report describes a patient with multicentric mixed type Castleman′s disease and concomitant non-Hodgkin′s lymphoma of diffuse large B cell type in the neck. Multicentric CD is a systemic illness with disseminated lymphadenopathy; its aggressive and usually fatal course is associated with infectious complications and risk for malignant tumors, such as lymphoma or Kaposi sarcoma.
Primary MALT lymphomas of the stomach: A pathological study of 18 cases Linfomas gástricos primarios tipo MALT: un estudio patológico de 18 casos
I. Venizelos,D. Tamiolakis,M. Lambropoulou,S. Bolioti
Revista Espa?ola de Enfermedades Digestivas , 2007,
Abstract: Aim: it is doubtful that whoever is suffering from gastric malt lymphoma will escape from the disease, if treated with medication against helicobacter pylori. Material and methods: a cohort of 18 patients was analysed. Ten hosts had primary gastric malt lymphoma and were treated with gastric resection as the initial therapy. Eight hosts received antibiotics against Helicobacter pylori as the initial treatment. In all 18 patients Helicobacter pylori status, endoscopic findings and pathology features were evaluated. Immunohistochemistry was performed to assess the bcl-2 and p53 status. Results: patients with low grade malt lymphoma: a) were Helicobacter pylori positive (5 of 5); b) had a superficial lesion (5 of 5); c) had no lymph node involvement (5 of 5); and d) were downstaged by comparison to patients with high grade tumor. Bcl-2 was positive in 4 of 5 low grade tumors, and p53 was positive in 12 of 13 high grade ones. Investigation of patients with 5-year follow up (n = 18) revealed that all but one low-grade tumors remained superficial with no progression. These tumors were bcl-2+/p53-, and the one with a bcl-2+/p53+ immunophenotype progressed to an ulcerated low-grade tumor after disappearance of Helicobacter pylori. Complete regression was found in 6 of 8 patients from the non surgically treated group (n = 8) after Helicobacter pylori eradication. These tumors were superficial/low grade/node negative/bcl-2+/p53 inconclusive (n = 2), superficial/low grade/node negative/bcl-2+/p53- (n = 2), and ulcerative/high grade/node negative/bcl-2+/p53- (n = 2). The two persistent tumors were ulcerative/high grade/node negative/bcl-2+/p53+. Conclusion: gastric malt lymphoma Helicobacter pylori+/superficial/low grade/bcl-2+/p53- will disappear after Helicobacter pylori eradication. Objetivo: es difícil que alguien que padezca un linfoma gástrico de tipo MALT pueda librarse de la enfermedad,... a menos que se le trate con medicación para Helicobacter pylori. Material y métodos: se analizó una cohorte de 18 pacientes. Diez huéspedes tenían linfoma gástrico de tipo MALT y se trataron con resección gástrica como tratamiento inicial. Ocho recibieron antibióticos frente a Helicobacter pylori como tratamiento inicial. En los 18 pacientes se evaluaron la presencia de Helicobacter pylori, los hallazgos endoscópicos y los rasgos patológicos. Se realizó una inmunohistoquímica para valorar el bcl-2 y el p53. Resultados: los pacientes con linfoma MALT de grado bajo: a) dieron positivo a Helicobacter pylori (5 de 5); b) tenían una lesión superficial (5 de 5); c) no tenían afe
Normal development of fetal hepatic haematopoiesis during the second trimester of gestation is upregulated by fibronectin expression in the stromal cells of the portal triads El desarrollo normal de la hematopoyesis hepática fetal durante el segundo trimestre de embarazo está regulado al alza por la expresión de fibronectina en las células del estroma de las tríadas portales
D. Tamiolakis,I. Venizelos,S. Nikolaidou,T. Jivanakis
Revista Espa?ola de Enfermedades Digestivas , 2007,
Abstract: Objective: in midtrimester fetuses the principal site of hematopoiesis is the liver. In hematopoietic organs, stromal cells such as fibroblasts, epithelial cells, and macrophage-like cells develop networks to maintain hematopoiesis, i.e. hematopoietic stem cell self-renewal, proliferation, and growth, by interaction with hematopoietic progenitor cells. ECM glycoproteins produced by the stromal cells are known to play a critical role in the regulation of cell growth and differentiation. Numerous soluble and membrane-bound factors directly regulating haematopoiesis have been documented, but little is known about fetal hepatic stromal cell activity and stromal extracellular matrix protein-fibronectin, on fetal hepatic haematopoiesis. The binding of late stage erythroid cells to fibronectin has been well characterized and is believed to be critical for the terminal stages of erythroid differentiation. The intention of this article is to determine the role of fibronectin in fetal hepatic hematopoietic proliferation and differentiation in different stages of development. Material and method: we examined and compared the immunohistochemical expression of fibronectin in the hepatic stromal portal fields in the 1st, 2nd, and 3rd trimester of gestation respectively, in relation to the appearance of CD34 progenitor hematopoietic, stromal progenitor and vascular endothelial positive cells. Results: our results demonstrated a quantitative difference in the second trimester of gestation concerning the expression of fibronectin in the connective tissue stroma of the hepatic portal fields over the equivalent expression of the protein in the first (p < 0.0001, t-test) and third trimester (p < 0.0001, t-test). Similar changes in the above period were found concerning the expression of CD34 during the second trimester of gestation, over the first (p < 0.0001, t-test) and third trimesters (p < 0.0001, t-test), suggesting a direct involvement of fibronectin in the sustaining of hematopoietic activity. Conclusions: our data provide evidence that an ECM glycoprotein component, fibronectin, plays a relevant role in hematopoiesis interaction between stromal cells and hematopoietic progenitor cells. Objetivo: en el segundo trimestre de la gestación, el principal foco de hematopoyesis del feto es el hígado. En los órganos hematopoyéticos, las células del estroma, como fibroblastos, células epiteliales y células de tipo macrófago, desarrollan redes para mantener la hematopoyesis, es decir, la auto-renovación, la proliferación y el crecimiento de las células madre hematopoyéticas, a
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