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Sham Procedure (sham + procedure)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Model density approach to the Kohn,Sham problem: Efficient extension of the density fitting technique

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2005
Uwe Birkenheuer
Abstract We present a novel procedure for treating the exchange-correlation contributions in the Kohn,Sham procedure. The approach proposed is fully variational and closely related to the so-called "fitting functions" method for the Coulomb Hartree problem; in fact, the method consistently uses this auxiliary representation of the electron density to determine the exchange-correlation contributions. The exchange-correlation potential and its matrix elements in a basis set of localized (atomic) orbitals can be evaluated by reusing the three-center Coulomb integrals involving fitting functions, while the computational cost of the remaining numerical integration is significantly reduced and scales only linearly with the size of the auxiliary basis. We tested the approach extensively for a large set of atoms and small molecules as well as for transition-metal carbonyls and clusters, by comparing total energies, atomization energies, structure parameters, and vibrational frequencies at the local density approximation and generalized gradient approximation levels of theory. The method requires a sufficiently flexible auxiliary basis set. We propose a minimal extension of the conventional auxiliary basis set, which yields essentially the same accuracy for the quantities just mentioned as the standard approach. The new method allows one to achieve substantial savings compared with a fully numerical integration of the exchange-correlation contributions. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source]

Cardiopulmonary, blood and peritoneal fluid alterations associated with abdominal insufflation of carbon dioxide in standing horses

EQUINE VETERINARY JOURNAL, Issue 3 2003
F. G. LATIMER
Summary Reasons for performing study: Abdominal insufflation is performed routinely during laparoscopy in horses to improve visualisation and facilitate instrument and visceral manipulations during surgery. It has been shown that high-pressure pneumoperitoneum with carbon dioxide (CO2) has deleterious cardiopulmonary effects in dorsally recumbent, mechanically ventilated, halothane-anaesthetised horses. There is no information on the effects of CO2 pneumoperitoneum on cardiopulmonary function and haematology, plasma chemistry and peritoneal fluid (PF) variables in standing sedated horses during laparoscopic surgery. Objectives: To determine the effects of high pressure CO2 pneumoperitoneum in standing sedated horses on cardiopulmonary function, blood gas, haematology, plasma chemistry and PF variables. Methods: Six healthy, mature horses were sedated with an i.v. bolus of detomidine (0.02 mg/kg bwt) and butorphanol (0.02 mg/kg bwt) and instrumented to determine the changes in cardiopulmonary function, haematology, serum chemistry and PF values during and after pneumoperitoneum with CO2 to 15 mmHg pressure for standing laparoscopy. Each horse was assigned at random to either a standing left flank exploratory laparoscopy (LFL) with CO2 pneumoperitoneum or sham procedure (SLFL) without insufflation, and instrumented for measurement of cardiopulmonary variables. Each horse underwent a second procedure in crossover fashion one month later so that all 6 horses had both an LFL and SLFL performed. Cardiopulmonary variables and blood gas analyses were obtained 5 mins after sedation and every 15 mins during 60 mins baseline (BL), insufflation (15 mmHg) and desufflation. Haematology, serum chemistry analysis and PF analysis were performed at BL, insufflation and desufflation, and 24 h after the conclusion of each procedure. Results: Significant decreases in heart rate, cardiac output and cardiac index and significant increases in mean right atrial pressure, systemic vascular resistance and pulmonary vascular resistance were recorded immediately after and during sedation in both groups of horses. Pneumoperitoneum with CO2 at 15 mmHg had no significant effect on cardiopulmonary function during surgery. There were no significant differences in blood gas, haematology or plasma chemistry values within or between groups at any time interval during the study. There was a significant increase in the PF total nucleated cell count 24 h following LFL compared to baseline values for LFL or SLFL at 24 h. There were no differences in PF protein concentrations within or between groups at any time interval. Conclusions: Pneumoperitoneum with CO2 during standing laparoscopy in healthy horses does not cause adverse alterations in cardiopulmonary, haematology or plasma chemistry variables, but does induce a mild inflammatory response within the peritoneal cavity. Potential relevance: High pressure (15 mmHg) pneumoperitoneum in standing sedated mature horses for laparoscopic surgery can be performed safely without any short-term or cumulative adverse effects on haemodynamic or cardiopulmonary function. [source]

Ovariectomy increases vascular calcification via the OPG/RANKL cytokine signalling pathway

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2008
B. G. Choi
ABSTRACT Background, Observational studies suggest a strong relationship between menopause and vascular calcification. Receptor activator of nuclear factor-,, ligand (RANKL) and osteoprotegerin (OPG) are critical regulators of bone remodelling and modulate vascular calcification. We assessed the hypothesis that ovariectomy increases vascular calcification via the OPG/RANKL axis. Materials and methods, Age-matched sexually mature rabbits were randomized to ovariectomy (OVX, n = 12) or sham procedure (SHAM, n = 12). One month post-procedure, atherosclerosis was induced by 15 months 0·2%-cholesterol diet and endothelial balloon denudations (at months 1 and 3). Aortic atherosclerosis was assessed in vivo by magnetic resonance imaging (MRI) at months 9 and 15. At sacrifice, aortas were harvested for ex vivo microcomputed tomography (µCT) and molecular analysis of the vascular tissue. Results, Vascular calcification density and calcific particle number were significantly greater in OVX than SHAM (8·4 ± 2·8 vs. 1·9 ± 0·6 mg cm,3, P = 0·042, and 94 ± 26 vs. 33 ± 7 particles cm,3, P = 0·046, respectively). Calcification morphology, as assessed by the arc angle subtended by the largest calcific particle, showed no difference between groups (OVX 33 ± 7° vs. SHAM 33 ± 5°, P = 0·99). By Western blot analysis, OVX increased the vascular OPG:RANKL ratio by 66%, P = 0·029, primarily by decreasing RANKL (P = 0·019). At month 9, MRI demonstrated no difference in atheroma volume between OVX and SHAM, and no significant change was seen by the end of the study. Conclusions, In contrast to bone, vascular OPG:RANKL ratio increased in response to ovariectomy with a corresponding fourfold increase in arterial calcification. This diametrical organ-specific response may explain the comorbid association of osteoporosis with calcifying atherosclerosis in post-menopausal women. [source]

Selective Vestibular Ablation by KTP Laser in Endolymphatic Hydrops,,

THE LARYNGOSCOPE, Issue 6 2001
Melanie Adamczyk MD
Abstract Objectives and Hypothesis Vertigo, the cause of disability in many patients with Ménière's disease, may be the result of the effects of endolymphatic hydrops on the semicircular canals. We hypothesize that intractable vertigo may be controlled by destruction of the semicircular canal neuroepithelium using visible light lasers without the need for extensive fenestration of the bony labyrinth. This study was designed to assess the cochlear effects of potassium titanyl phosphate (KTP) laser-assisted triple semicircular canal ablation (TSCA) in endolymphatic hydrops. Study Design Randomized, prospective, and controlled. Methods Forty-one adult guinea pigs underwent either a unilateral endolymphatic duct occlusion to induce hydrops or a sham procedure. Ten weeks after induction of the hydrops, a KTP laser-assisted TSCA or a sham surgery was performed. Results Electrocochleographic thresholds to clicks and tone-bursts (2,20 kHz) did not change significantly up to 4 weeks after TSCA in hydropic ears. Cross-sectional histology confirmed the presence of hydrops and the ablation of the semicircular canals. Cochlear whole-mounts for hair cell counts showed no significant loss of outer or inner hair cells in hydropic ears treated with TSCA. Conclusion KTP laser-assisted TSCA can be performed in the guinea pig model of endolymphatic hydrops without significant loss of hearing. Evaluation of this technique may be warranted in patients with intractable Ménière's disease. [source]

Early Hemodynamic Injury During Donor Brain Death Determines the Severity of Primary Graft Dysfunction after Lung Transplantation

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 1 2007
V. S. Avlonitis
Sympathetic discharge and hypertensive crisis often accompany brain death, causing neurogenic pulmonary edema. Progressive systemic inflammatory response develops, which can injure the lung further. We investigated whether (a) early hemodynamic injury during donor brain death increases reperfusion injury after lung transplantation and (b) delaying lung recovery would augment reperfusion injury further, because of the progressive systemic inflammatory response in the donor. Brain death was induced by intracranial balloon inflation in rats, with or without ,-adrenergic blockade pretreatment to prevent the hypertensive crisis. Another group of rats had a sham procedure. Lungs were retrieved 15 min after brain death or sham procedure and reperfused using recipient rats. In a fourth group, brain death was induced and the lungs were retrieved 5 h after brain death and reperfused. Postreperfusion, lungs retrieved early from untreated brain-dead donors developed more severe reperfusion injury, as assessed by functional parameters and inflammatory markers, than those from sham or alpha-blockade-treated donors. Lungs retrieved late from brain-dead donors had similar inflammatory markers after reperfusion to those retrieved early, but significantly lower pulmonary vascular resistance. Early hemodynamic damage during donor brain death increases reperfusion injury after lung transplantation. Delaying retrieval may allow the lung to recover from the hemodynamic injury. [source]