ABSTRACT
The development of effective neurobiological adjuvants to rehabilitation of paresis caused by stroke will depend on understanding mechanisms of paresis. Our objective was to determine the extent to which upper-limb (UL) paresis after nonlacunar ischemic middle cerebral artery (MCA) distribution stroke is caused by infarction of posterior periventricular white matter (PVWM), where corticospinal fibers serving movement descend, and caused by infarction of the arm-hand region of precentral gyrus (ahPCG). We conducted a blinded, retrospective analysis of computed tomography and magnetic resonance imaging from a convenience sample of 64 prospectively evaluated subjects with UL paresis resulting from MCA distribution stroke. Of the subjects, 96.5% had PVWM involvement while 53% had minimal or no ahPCG involvement. Even in subjects with no UL function, 56% had very minimal infarction (<25%) of the ahPCG. Degree of paresis was statistically associated with presence or absence of detectable posterior PVWM damage but not with extent of ahPCG involvement. These preliminary findings suggest that posterior PVWM involvement may be a major, if not the principal, determinant of paresis in all hemispheric ischemic strokes and motivate further prospective studies of this problem.
Subject(s)
Arm/physiopathology , Cerebrum/diagnostic imaging , Infarction, Middle Cerebral Artery/complications , Paresis/physiopathology , Stroke, Lacunar/diagnostic imaging , Adult , Aged , Aged, 80 and over , Cerebrum/blood supply , Female , Humans , Infarction, Middle Cerebral Artery/diagnostic imaging , Infarction, Middle Cerebral Artery/physiopathology , Magnetic Resonance Imaging , Male , Middle Aged , Paresis/etiology , Pilot Projects , Retrospective Studies , Single-Blind Method , Stroke, Lacunar/complications , Stroke, Lacunar/physiopathology , Tomography, X-Ray ComputedABSTRACT
The effectiveness of Fenton process in municipal landfill leachate treatment, as a pre- or post-treatment approach, has been demonstrated. However, no general recommendations of universal validity could be made in the term of optimized conditions affecting Fenton process. At the first stage of this study, collected leachate samples from Aradkooh site, Tehran, Iran, were investigated using one-factor-at-a-time method to find out optimum coagulation pH and flocculation time values. Subsequently, the obtained results in addition to data issued previously by the authors were employed to develop a predictive model of the true response surface, namely chemical oxygen demand (COD) removal efficiency. Finally, the main parameters of Fenton procedure, i.e. initial pH, [H(2)O(2)]/[Fe(2+)] molar ratio, Fe(2+) dosage, and coagulation pH were optimized taking advantage of the above-mentioned quadratic model. The derived second-order model included both significant linear and quadratic terms and seemed to be adequate in predicting responses (R(2)=0.9896 and prediction R(2)=0.6954). It was found that the interaction between initial pH and Fe(2+) dosage has a significant effect on COD removal. While, the optimal [H(2)O(2)]/[Fe(2+)] molar ratio was independent of ferrous ion dosage. The optimum conditions for the maximum COD removal of 50.76% for the parameters of initial pH, [H(2)O(2)]/[Fe(2+)] molar ratio, Fe(2+) dosage, and coagulation pH were found to be 5.8, 8.0, 22,500 mg/L, and 8.7 respectively.
Subject(s)
Hydrogen Peroxide/chemistry , Iron/chemistry , Models, Theoretical , Waste Disposal, Fluid , Water Pollutants, Chemical/chemistry , Hydrogen-Ion Concentration , Regression Analysis , Time FactorsABSTRACT
The aim of this study was to investigate the use of the Fenton oxidation process for treating leachate from a municipal solid waste landfill collected from Aradkooh site, Tehran, Iran. The focus of the study was to evaluate the process performance by COD removal efficiency. Results indicate that the optimum amounts of oxidation parameters in the Fenton process were as follows: oxidation pH = 4, H(2)O(2)/Fe(2+) molar ratio = 4-5, Fe(2+) ion dosage = 11,200-19,600 mg L(-1) and oxidation time = 20-30 min. In addition, the maximum amount of COD that it was possible to remove by the Fenton process was about 47% of the initial value (i.e. 35 000 mg L(-1)). This level of removal was achieved by using 19 600 mg of Fe(2+) per litre of leachate with H(2)O(2)/Fe(2+) molar ratio of 4.5, for the following operational conditions: oxidation pH = 4; coagulation pH = 7.5; oxidation time = 100 min; coagulation time = 30 min. Furthermore, it was found that 90% of oxidation occurred during the first 20 min of the oxidation stage. All the experiments, except for oxidation time, were conducted in two rounds for better optimization.
Subject(s)
Hydrogen Peroxide/chemistry , Iron/chemistry , Refuse Disposal/methods , Water Pollutants, Chemical/chemistry , Biological Oxygen Demand Analysis , Hydrogen-Ion Concentration , Oxidation-Reduction , Oxygen/analysis , Water Pollutants, Chemical/analysisABSTRACT
We present the case of a 29-year-old woman with an alien limb and callosal disconnection syndrome who was diagnosed with moya-moya disease. We discuss the potential mechanisms responsible for the alien limb syndrome.
