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result(s) for
"Karageorgos, Athanasios"
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Accuracy of pedicle screw placement: a systematic review of prospective in vivo studies comparing free hand, fluoroscopy guidance and navigation techniques
by
Xenakis, Theodoros A.
,
Paschos, Nikolaos K.
,
Politis, Angelos N.
in
Bone Screws
,
Computed tomography
,
Cortex
2012
Introduction
With the advances and improvement of computer-assisted surgery devices, computer-guided pedicle screws insertion has been applied to the lumbar, thoracic and cervical spine. The purpose of the present study was to perform a systematic review of all available prospective evidence regarding pedicle screw insertion techniques in the thoracic and lumbar human spine.
Materials and methods
We considered all prospective in vivo clinical studies in the English literature that assessed the results of different pedicle screw placement techniques (free-hand technique, fluoroscopy guided, computed tomography (CT)-based navigation, fluoro-based navigation). MEDLINE, OVID, and Springer databases were used for the literature search covering the period from January 1950 until May 2010.
Results
26 prospective clinical studies were eventually included in the analysis. These studies included in total 1,105 patients in which 6,617 screws were inserted. In the studies using free-hand technique, the percentage of the screws fully contained in the pedicle ranged from 69 to 94%, with the aid of fluoroscopy from 28 to 85%, using CT navigation from 89 to 100% and using fluoroscopy-based navigation from 81 to 92%. The screws positioned with free-hand technique tended to perforate the cortex medially, whereas the screws placed with CT navigation guidance seemed to perforate more often laterally.
Conclusions
In conclusion, navigation does indeed exhibit higher accuracy and increased safety in pedicle screw placement than free-hand technique and use of fluoroscopy.
Journal Article
Host cystathionine-γ lyase derived hydrogen sulfide protects against Pseudomonas aeruginosa sepsis
by
Platoni, Kalliopi
,
Szabo, Csaba
,
Papapetropoulos, Andreas
in
Animals
,
Antibiotics
,
Antiinfectives and antibacterials
2021
Hydrogen sulfide (H 2 S) has recently been recognized as a novel gaseous transmitter with several anti-inflammatory properties. The role of host- derived H 2 S in infections by Pseudomonas aeruginosa was investigated in clinical and mouse models. H 2 S concentrations and survival was assessed in septic patients with lung infection. Animal experiments using a model of severe systemic multidrug-resistant P . aeruginosa infection were performed using mice with a constitutive knock-out of cystathionine-γ lyase ( Cse) gene ( Cse -/- ) and wild-type mice with a physiological expression ( Cse +/+ ). Experiments were repeated in mice after a) treatment with cyclophosphamide; b) bone marrow transplantation (BMT) from a Cse +/+ donor; c) treatment with H 2 S synthesis inhibitor aminooxyacetic acid (ΑΟΑΑ) or propargylglycine (PAG) and d) H 2 S donor sodium thiosulfate (STS) or GYY3147. Bacterial loads and myeloperoxidase activity were measured in tissue samples. The expression of quorum sensing genes (QS) was determined in vivo and in vitro. Cytokine concentration was measured in serum and incubated splenocytes. Patients survivors at day 28 had significantly higher serum H 2 S compared to non-survivors. A cut- off point of 5.3 μΜ discriminated survivors with sensitivity 92.3%. Mortality after 28 days was 30.9% and 93.7% in patients with H 2 S higher and less than 5.3 μΜ (p = 7 x 10 −6 ). In mice expression of Cse and application of STS afforded protection against infection with multidrug-resistant P . aeruginosa . Cyclophosphamide pretreatment eliminated the survival benefit of Cse +/+ mice, whereas BMT increased the survival of Cse -/- mice. Cse -/- mice had increased pathogen loads compared to Cse +/+ mice. Phagocytic activity of leukocytes from Cse -/- mice was reduced but was restored after H 2 S supplementation. An H 2 S dependent down- regulation of quorum sensing genes of P . aeruginosa could be demonstrated in vivo and in vitro . Endogenous H 2 S is a potential independent parameter correlating with the outcome of P . aeruginosa . H 2 S provides resistance to infection by MDR bacterial pathogens.
Journal Article
Prevalence of Small Intestinal Bacterial Overgrowth Syndrome in Patients with Non-Alcoholic Fatty Liver Disease/Non-Alcoholic Steatohepatitis: A Cross-Sectional Study
by
Gkolfakis, Paraskevas
,
Triantafyllou, Konstantinos
,
Mathur, Ruchi
in
Alcohol
,
Bacteria
,
Catheters
2023
Introduction: Non-alcoholic fatty liver disease (NAFLD) is a multifactorial, wide-spectrum liver disorder. Small intestinal bacterial overgrowth (SIBO) is characterized by an increase in the number and/or type of colonic bacteria in the upper gastrointestinal tract. SIBO, through energy salvage and induction of inflammation, may be a pathophysiological factor for NAFLD development and progression. Aim/Methods: Consecutive patients with histological, biochemical, or radiological diagnosis of any stage of NAFLD (non-alcoholic fatty liver [NAFL], non-alcoholic steatohepatitis [NASH], cirrhosis) underwent upper gastrointestinal endoscopy. Duodenal fluid (2cc) was aspirated from the 3rd–4th part of duodenum into sterile containers. SIBO was defined as ≥103 aerobic colony-forming units (CFU)/mL of duodenal aspirate and/or the presence of colonic-type bacteria. Patients without any liver disease undergoing gastroscopy due to gastroesophageal reflux disease (GERD) comprised the healthy control (HC) group. Concentrations (pg/mL) of tumor necrosis factor alpha (TNFα), interleukin (IL)-1β, and IL-6 were also measured in the duodenal fluid. The primary endpoint was to evaluate the prevalence of SIBO in NAFLD patients, while the comparison of SIBO prevalence among NAFLD patients and healthy controls was a secondary endpoint. Results: We enrolled 125 patients (51 NAFL, 27 NASH, 17 cirrhosis, and 30 HC) aged 54 ± 11.9 years and with a weight of 88.3 ± 19.6 kg (NAFLD vs. HC 90.7 ± 19.1 vs. 80.8 ± 19.6 kg, p = 0.02). Overall, SIBO was diagnosed in 23/125 (18.4%) patients, with Gram-negative bacteria being the predominant species (19/23; 82.6%). SIBO prevalence was higher in the NAFLD cohort compared to HC (22/95; 23.2% vs. 1/30; 3.3%, p = 0.014). Patients with NASH had higher SIBO prevalence (6/27; 22.2%) compared to NAFL individuals (8/51; 15.7%), but this difference did not reach statistical significance (p = 0.11). Patients with NASH-associated cirrhosis had a higher SIBO prevalence compared to patients with NAFL (8/17; 47.1% vs. 8/51; 15.7%, p = 0.02), while SIBO prevalence between patients with NASH-associated cirrhosis and NASH was not statistically different (8/17; 47.1% vs. 6/27; 22.2%, p = 0.11). Mean concentration of TNF-α, IL-1β, and IL-6 did not differ among the different groups. Conclusion: The prevalence of SIBO is significantly higher in a cohort of patients with NAFLD compared to healthy controls. Moreover, SIBO is more prevalent in patients with NASH-associated cirrhosis compared to patients with NAFL.
Journal Article
Generalized inverses of the vandermonde matrix: Applications in control theory
by
Pantelous, Athanasios A.
,
Karageorgos, Athanasios D.
in
Analysis
,
Applied mathematics
,
Control
2013
In the literature of control and system theory, several explicit formulae appeared for solving square Vandermonde systems and computing the inverse of it. In the present paper, we will discuss and present analytically the generalized inverses of the rectangular and square Vandermonde matrix. These matrices have been appeared recently in an interesting control and system theory problem, where the change of the initial state of a linear descriptor system in (almost) zero time is required.
Journal Article
Designing the sampling period of a discretized LTI descriptor (regular) system with inputs
by
Pantelous, Athanasios A.
,
Kalogeropoulos, Grigoris I.
,
Karageorgos, Athanasios D.
in
Analysis
,
Approximation
,
Control
2011
In this brief paper, a new sharper upper bound for the error ‖
x
(
kT
) −
x
k
‖ that derives from the procedure of discretization of the solution of a Linear descriptor (regular) differential input system with consistent initial conditions, and Time-Invariant coefficients (LTI) is calculated and fully discussed. Practically speaking, considering numerous applications in engineering (especially in robotics and digital control) and computer science, we are very interested in determining such kind of upper bounds, since they are significant in the design process of the sampling period
T
.
Journal Article
Solution Properties of Linear Descriptor (Singular) Matrix Differential Systems of Higher Order with (Non-) Consistent Initial Conditions
by
Athanasios D. Karageorgos
,
Athanasios A. Pantelous
,
Grigoris I. Kalogeropoulos
in
Agricultural engineering
,
Studies
,
System theory
2010
In some interesting applications in control and system theory, linear descriptor (singular) matrix differential equations of higher order with time-invariant coefficients and (non-) consistent initial conditions have been used. In this paper, we provide a study for the solution properties of a more general class of the Apostol-Kolodner-type equations with consistent and nonconsistent initial conditions.
Journal Article
Effect of intravenous clarithromycin in patients with sepsis, respiratory and multiple organ dysfunction syndrome: a randomized clinical trial
2022
Background
Clarithromycin may act as immune-regulating treatment in sepsis and acute respiratory dysfunction syndrome. However, clinical evidence remains inconclusive. We aimed to evaluate whether clarithromycin improves 28-day mortality among patients with sepsis, respiratory and multiple organ dysfunction syndrome.
Methods
We conducted a multicenter, randomized, clinical trial in patients with sepsis. Participants with ratio of partial oxygen pressure to fraction of inspired oxygen less than 200 and more than 3 SOFA points from systems other than the respiratory function were enrolled between December 2017 and September 2019. Patients were randomized to receive 1 gr of clarithromycin or placebo intravenously once daily for 4 consecutive days. The primary endpoint was 28-day all-cause mortality. Secondary outcomes were 90-day mortality; sepsis response (defined as at least 25% decrease in SOFA score by day 7); sepsis recurrence; and differences in peripheral blood cell populations and leukocyte transcriptomics.
Results
Fifty-five patients were allocated to each arm. By day 28, 27 (49.1%) patients in the clarithromycin and 25 (45.5%) in the placebo group died (risk difference 3.6% [95% confidence interval (CI) − 15.7 to 22.7];
P
= 0.703, adjusted OR 1.03 [95%CI 0.35–3.06];
P
= 0.959). There were no statistical differences in 90-day mortality and sepsis response. Clarithromycin was associated with lower incidence of sepsis recurrence (OR 0.21 [95%CI 0.06–0.68];
P
= 0.012); significant increase in monocyte HLA-DR expression; expansion of non-classical monocytes; and upregulation of genes involved in cholesterol homeostasis. Serious and non-serious adverse events were equally distributed.
Conclusions
Clarithromycin did not reduce mortality among patients with sepsis with respiratory and multiple organ dysfunction. Clarithromycin was associated with lower sepsis recurrence, possibly through a mechanism of immune restoration.
Clinical trial registration
clinicaltrials.gov identifier
NCT03345992
registered 17 November 2017; EudraCT 2017-001056-55.
Journal Article
Transferring Instantly the State of Higher-Order Linear Descriptor (Regular) Differential Systems Using Impulsive Inputs
by
Pantelous, Athanasios A.
,
Kalogeropoulos, Grigoris I.
,
Karageorgos, Athanasios D.
in
Control theory
,
Derivatives
,
Linear algebra
2009
In many applications, and generally speaking in many dynamical differential systems, the problem of transferring the initial state of the system to a desired state in (almost) zero-time time is desirable but difficult to achieve. Theoretically, this can be achieved by using a linear combination of Dirac δ-function and its derivatives. Obviously, such an input is physically unrealizable. However, we can think of it approximately as a combination of small pulses of very high magnitude and infinitely small duration. In this paper, the approximation process of the distributional behaviour of higher-order linear descriptor (regular) differential systems is presented. Thus, new analytical formulae based on linear algebra methods and generalized inverses theory are provided. Our approach is quite general and some significant conditions are derived. Finally, a numerical example is presented and discussed.
Journal Article
Discretizing LTI Descriptor (Regular) Differential Input Systems with Consistent Initial Conditions
by
Pantelous, Athanasios A.
,
Kalogeropoulos, Grigoris I.
,
Karageorgos, Athanasios D.
in
Approximation
,
Physics
,
Studies
2010
A technique for discretizing efficiently the solution of a Linear descriptor (regular) differential input system with consistent initial conditions, and Time-Invariant coefficients (LTI) is introduced and fully discussed. Additionally, an upper bound for the error ‖x¯(kT)−x¯k‖ that derives from the procedure of discretization is also provided. Practically speaking, we are interested in such kind of systems, since they are inherent in many physical, economical and engineering phenomena.
Journal Article
BioFire® FilmArray® Pneumonia Panel for Severe Lower Respiratory Tract Infections: Subgroup Analysis of a Randomized Clinical Trial
2021
IntroductionThe epidemiology of severe lower respiratory tract infections (LRTI) is constantly changing. We aimed to describe it using the BioFire® FilmArray® Pneumonia plus (PNplus) Panel.MethodsIn a sub-study of the PROGRESS trial, sputum samples of 90 patients with sepsis and LRTI were retrospectively studied. The primary endpoint was the comparative detection rate of pathogens between conventional microbiology and PNplus Panel; secondary endpoints were microbiology and the association with the inflammatory host response.ResultsFifty-six patients with community-acquired pneumonia without risk factors for multidrug-resistant (MDR) pathogens and another 34 patients with risk factors for MDR were studied; median pneumonia severity index (PSI) was 113 (88–135). PNplus detection rate was 72.2% compared to 10% by conventional microbiology (p < 0.001); Streptococcus pneumoniae was the most common pathogen. PSI and procalcitonin were greater among patients with bacterial pathogens than viral pathogens. Median procalcitonin was 0.49 ng/ml and 0.18 ng/ml among patients with ≥ 105 and < 105 copies/ml of detected bacteria, respectively (p = 0.004). Resistance reached 14.4%.ConclusionPNplus detects severe pneumonia pathogens at a greater rate than conventional microbiology. High levels of inflammation accompany bacterial detection.Trial RegistrationPROGRESS, ClinicalTrials.gov NCT03333304, 06/11/2017.
Journal Article