Can retrograde perfusion mitigate cerebral injury after particulate embolization? A study in a chronic porcine model

OBJECTIVE: We assessed the impact on histologic and behavioral outcome of an interval of retrograde cerebral perfusion after arterial embolization, comparing retrograde cerebral perfusion with and without inferior vena caval occlusion with continued antegrade perfusion. METHODS: Sixty Yorkshire pigs (27 to 30 kg) were randomly assigned to the following groups: antegrade cerebral perfusion control; antegrade cerebral perfusion after embolization; retrograde cerebral perfusion control; retrograde cerebral perfusion after embolization; retrograde cerebral perfusion with inferior vena cava occlusion, retrograde cerebral perfusion with inferior vena cava occlusion control, and retrograde cerebral perfusion with inferior vena cava occlusion after embolization. After cooling to 20 degrees C, a bolus of 200 mg of polystyrene microspheres 250 to 750 (microm diameter (or saline solution) was injected into the isolated aortic arch. After 5 minutes of antegrade cerebral perfusion, 25 minutes of antegrade cerebral perfusion, retrograde cerebral perfusion, or retrograde cerebral perfusion with inferior vena cava occlusion was instituted. After the operation, all animals underwent daily assessment of neurologic status until the time of death on day 7. RESULTS: Aortic arch return, cerebral vascular resistance, and oxygen extraction data during retrograde cerebral perfusion showed differences, suggesting that more effective flow occurs during retrograde cerebral perfusion with inferior vena cava occlusion, which also resulted in more pronounced fluid sequestration. Microsphere recovery from the brain revealed significantly fewer emboli after retrograde cerebral perfusion with inferior vena cava occlusion. Behavioral scores showed full recovery in all but one control animal (after retrograde cerebral perfusion with inferior vena cava occlusion) by day 7 but were considerably lower after embolization, with no significant differences between groups. The extent of histopathologic injury was not significantly different among embolized groups. Although no histopathologic lesions were present in either the antegrade cerebral perfusion control group or the retrograde cerebral perfusion control group, mild significant ischemic damage occurred after retrograde cerebral perfusion with inferior vena cava occlusion even in control animals. CONCLUSIONS: Although effective washout of particulate emboli from the brain can be achieved with retrograde cerebral perfusion with inferior vena cava occlusion, no advantage of retrograde cerebral perfusion with inferior vena cava occlusion after embolization is seen from behavioral scores, electroencephalographic recovery, or histopathologic examination; retrograde cerebral perfusion with inferior vena cava occlusion results in greater fluid sequestration and mild histopathologic injury even in control animals. Retrograde cerebral perfusion with inferior vena cava occlusion shows clear promise in the management of embolization, but further refinements must be sought to address its still worrisome potential for harm.     

Intraclass correlation for two-by-two tables under three sampling designs

Several sampling designs for assessing agreement between two binary classifications on each of n subjects lead to data arrayed in a four-fold table. Following Kraemer's (1979, Psychometrika 44, 461-472) approach, population models are described for binary data analogous to quantitative data models for a one-way random design, a two-way mixed design, and a two-way random design. For each of these models, parameters representing intraclass correlation are defined, and two estimators are proposed, one from constructing ANOVA-type tables for binary data, and one by the method of maximum likelihood. The maximum likelihood estimator of intraclass correlation for the two-way mixed design is the same as the phi coefficient (Chedzoy, 1985, in Encyclopedia of Statistical Sciences, Vol. 6, New York: Wiley). For moderately large samples, the ANOVA estimator for the two-way random design approximates Cohen's (1960, Psychological Measurement 20, 37-46) kappa statistic. Comparisons among the estimators indicate very little difference in values for tables with marginal symmetry. Differences among the estimators increase with increasing marginal asymmetry, and with average prevalence approaching .50.     

Reproducibility and accuracy of interactive segmentation procedures for image analysis in cytology

The segmentation of nuclear images is a crucial step in the development of procedures using image analysis for the cytological diagnosis of cancer. The purpose of this study is to evaluate the reproducibility and accuracy of several interactive segmentation methods which can be used in this context. Four methods were studied: a thresholding-based method enabling selection of intensity histogram contrast and brightness, manual tracing with a stylus, and arc- and ellipse-fitting routines. Features of nuclear size and shape were derived from nuclei segmented on repeated occasions by several individuals. Variance component models provided a statistical framework for evaluating the intraobserver and interobserver variability of these measurements in terms of their intraclass correlation coefficients. Of the methods tested, the arc-fitting segmentation method gave the most reproducible results, and thresholding the least. Reproducibility was generally very high both between individuals and for repeated segmentations by a single individual. Accuracies of area measurements for the various methods, as determined with respect to point counting, paralleled the reproducibilities of the methods. Sample size requirements were observed to be more dependent on the biological variability of the tissue sampled than on the particular segmentation method or on the number of individuals performing segmentation.     

Annual Rainfall Forecasting Using Hybrid Artificial Intelligence Model: Integration of Multilayer Perceptron with Whale Optimization Algorithm

Water Resources Management - Rainfall, as one of the key components of hydrological cycle, plays an undeniable role for accurate modelling of other hydrological components. Therefore, a precise...     

Retrograde cerebral perfusion enhances cerebral protection during prolonged hypothermic circulatory arrest: a study in a chronic porcine model

BACKGROUND: This study was undertaken to confirm earlier findings that retrograde cerebral perfusion (RCP) can improve cerebral outcome after prolonged hypothermic circulatory arrest (HCA), and to determine whether RCP with inferior vena caval occlusion, which is more effective in removing particulate emboli, is superior to conventional RCP in enhancing cerebral protection. METHODS: Sixty-two pigs (27 to 30 kg) were randomly assigned to undergo one of the following for 90 minutes at 20 degrees C: antegrade cerebral perfusion (ACP); conventional RCP (RCP); RCP with occlusion of the inferior vena cava (RCP-O), or HCA with the head packed in ice. RCP flow was regulated to a sagittal sinus pressure of 20 mm Hg. Hemodynamic, electrophysiologic, and metabolic monitoring were carried out until 4 hours after rewarming, daily behavioral and neurologic assessments until elective sacrifice on day 7, and histologic analysis of the brain after death. RESULTS: Complete behavioral recovery was seen in all surviving animals by day 5 after ACP or RCP, but in only 83% after RCP-O and 50% after HCA (p = 0.001). A histopathologic score of 2 or more, indicating more than mild injury, was not found in any animal after ACP, in 27% after RCP, in 47% after HCA, and in 68% after RCP-O (p = 0.002). The median oxygen consumption was 6.66 mL/min after ACP, 1.37 mL/min with RCP, and 1.02 mL/min with RCP-O (p < 0.0001). The median amount of fluid sequestered was 2,450 mL after RCP-O, 760 mL after RCP, and -200 mL after ACP (p < 0.0001). CONCLUSIONS: Conventional RCP without inferior vena caval occlusion results in a significantly better outcome than RCP-O after prolonged HCA, despite more efficient cerebral perfusion during RCP-O, and also provides cerebral protection superior to prolonged HCA alone, but care must be taken during its implementation to minimize cerebral edema and other possible causes of retroperfusion-related cerebral injury.     

Rainfall-runoff modelling of water resources in the upper Senegal River basin

The streamflow series for the upstream basin of the Senegal River is marked by considerable gaps. The objective of this article is to simulate and extend hydrological data, using the GR2M rainfall-runoff model. A sensitivity analysis of the model to rainfall and water holding capacity input data was performed. This analysis was performed after calculating catchment rainfall, mean potential evapotranspiration, and maximum, minimum and mean water holding capacity. The best combination of input data was chosen by catchment based on the Nash-Sutcliffe criterion. Then cross calibration-validation tests were performed, using the selected input data to choose model parameter sets.     

Mutational analysis of the active site and antibody epitopes of the complement-inhibitory glycoprotein, CD59

The Ly-6 superfamily of cell surface molecules includes CD59, a potent regulator of the complement system that protects host cells from the cytolytic action of the membrane attack complex (MAC). Although its mechanism of action is not well understood, CD59 is thought to prevent assembly of the MAC by binding to the C8 and/or C9 proteins of the nascent complex. Here a systematic, structure-based mutational approach has been used to determine the region(s) of CD59 required for its protective activity. Analysis of 16 CD59 mutants with single, highly nonconservative substitutions suggests that CD59 has a single active site that includes Trp-40, Arg-53, and Glu-56 of the glycosylated, membrane-distal face of the disk-like extra-cellular domain and, possibly, Asp-24 positioned at the edge of the domain. The putative active site includes residues conserved across species, consistent with the lack of strict homologous restriction previously observed in studies of CD59 function. Competition and mutational analyses of the epitopes of eight CD59-blocking and non-blocking monoclonal antibodies confirmed the location of the active site. Additional experiments showed that the expression and function of CD59 are both glycosylation independent.     

Prolonged surgery increases the likelihood of admission of scheduled ambulatory surgery patients

STUDY OBJECTIVE: To identify variables influencing the likelihood of unanticipated admission following scheduled ambulatory surgery. DESIGN: Retrospective case-controlled chart review study. SETTING: A large academic tertiary care hospital. PATIENTS: 8,549 ASA physical status I, II, III, and IV patients who underwent scheduled ambulatory surgery in 1991. MEASUREMENTS AND MAIN RESULTS: Of the 8,549 patients, 216 were admitted, with complete medical record information available for 167 of the admitted patients. The most common reasons for admission among the 167 were surgical (43%), anesthetic (28%), and medical (17%) complications. Odds for admission following long surgery (of at least 60 minutes) were 7.5 times (p < 0.001) greater than following short surgery (under 60 minutes). Among long cases, independent variables influencing admission were: general anesthesia [odds ratio 20.8; 95% confidence interval (CI) 4.4 to 45.6], and monitored anesthesia care or regional anesthesia (combined odds ratio 8.3; 95% CI 1.7 to 40.8). ASA physical status and patient age did not significantly influence admission rate for long cases. For short cases, patients over 65 years (odds ratio 5.6; 95% CI 2.6 to 12.0), ASA physical status III or IV (odds ratio 4.8; 95% CI 2.0 to 11.6), use of general anesthesia (odds ratio 4.7; 95% CI 1.5 to 14.2), and monitored anesthesia care or regional anesthesia (odds ratio 3.1; 95% CI 1.0 to 10.1) independently influenced the likelihood of admission. Type of surgery and gender had no detectable effect on admission. CONCLUSIONS: Surgery duration of 60 minutes or longer was the most important predictor of unanticipated admission following scheduled ambulatory surgery.     

Sialyl-Tn antigen as a marker of colon cancer risk in ulcerative colitis: relation to dysplasia and DNA aneuploidy

Radiopharmaceuticals are essential to the performance of nuclear medicine procedures. These radioactive drugs consist of two components: a drug component for localization in a specific tissue or organ and a radioactive component for diagnostic or therapeutic purposes. The majority of radiopharmaceuticals are used for diagnostic imaging procedures. The radioisotopes used for radiopharmaceuticals are produced in a number of ways: as by-products of fission, by means of neutron activation, by cyclotrons, and by generators. These methods produce isotopes with both desirable and undesirable properties. Approximately 80% of all nuclear medicine procedures performed in the United States use radiopharmaceuticals labeled with technetium-99m. The chemical properties of technetium allow relatively simple preparation of Tc-99m compounds by using reagent kits. Quality control testing of radiopharmaceuticals is routinely performed to ensure compliance with various purity standards such as assay for radioactivity, radionuclidic purity, chemical purity, radiochemical purity, pharmaceutical purity, and biologic purity.     

The effect of a propofol-based sedation technique on cumulative embryo scores, clinical pregnancy rates, and implantation rates in patients undergoing embryo transfers with donor oocytes

STUDY OBJECTIVE: To determine the effect, if any, of a propofol-based sedation technique on the reproductive outcomes of patients undergoing embryo transfers with donor oocytes. These ova recipients form a unique subgroup, whose clinical outcomes are unrelated to direct anesthetic effects on their reproductive tracts. DESIGN: Retrospective chart review. SETTING: A 1200-bed university medical center. PATIENTS: 117 patients who received fresh embryo transfer cycles between January 1991 and December 1995. MEASUREMENTS AND MAIN RESULTS: The anesthesia records of 106 women who donated ova were reviewed for propofol usage during the transvaginal needle aspiration of the ova. The medical records of the 117 patients who received these donated embryos were reviewed for cumulative embryo scores, clinical pregnancy rates, and implantation rates. Fourteen patients received ova from women who were sedated with fentanyl and midazolam during ovum retrievals, while 103 patients received ova from women who had been given fentanyl, midazolam, and propofol in doses of 1.87 mg/kg to 8 mg/kg. The pregnancy rate among all patients who received ova from women who received propofol (44 of 103 = 42.7%) was 14.1% greater than those whose ovum donors did not receive propofol (4 of 14 = 28.6). 78.6% of both propofol and non propofol-exposed groups had cumulative embryo scores of greater than 50. Among patients who became pregnant, 52.3% of propofol-exposed and 50% of nonpropofol-exposed cases had greater than 20% implantation rates. CONCLUSION: There is no evidence from our data that the administration of propofol during the aspiration of ovarian follicles for oocyte donation had a negative impact on the oocytes as measured by cumulative embryo scores, probability of a clinical pregnancy, or implantation rate.