Minimal brain dysfunction and methylphenidate.
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Biomedical subjects
S V Pizzo
Publications and source records attributed to S V Pizzo.
The effect of fibrin-stabilizing factor on the subunit structure of human fibrin.
The formation of human fibrin from fibrinogen has been examined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate, a method which separates a mixture of proteins on the basis of differences in molecular weight. It has been found that the plasma from a patient with a congenital deficiency of fibrin-stabilizing factor forms clots lacking the cross links among the alpha- and gammachains found in normal, cross-linked human fibrin. The addition of purified fibrin-stabilizing factor or normal plasma to the deficient plasma results in extensive cross-linking of the chains. Thus, the fibrinogen in the fibrin-stabilizing factor deficient plasma appears to be normal and forms fibrin which contains dimeric, cross-linked gamma-chains and polymeric, high molecular weight forms of alpha-chains. By the use of these electrophoretic methods, it has also been possible to develop a highly sensitive method for measuring the content of fibrin-stabilizing factor in plasma. This method depends upon the use of urea-treated fibrinogen, which is completely devoid of fibrin-stabilizing factor, but which forms the usual cross-linked subunits after conversion to fibrin by thrombin in the presence of fibrin-stabilizing factor.
Acetates↗
Purification and subunit structure of human plasma and platelet fibrin-stabilizing factor.
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Blood Platelets↗
Transcatheter electrocoagulation: a therapeutic angiographic technique for vessel occlusion.
Previous work has shown that localized electrocoagulation of blood vessels using direct current applied by catheter placed electrodes is feasible. In vitro and in vivo experiments showed that clot size and thrombosis of vessels are directly related to the product of the amount and duration of the current. Surgically created splenic hemorrhage was well controlled in 9 of 10 animals. The vessels remained permanently occluded after electrocoagulation in 8 of 9 animals. Pathological studies of all the vessels showed intimal damage at the sites of occlusion. These experiments indicate that clot formation may be a product of both intimal damage and platelet attraction to the positive electrode. The technique has advantages over embolization since no foreign material is injected and a localized clot is produced at the tip of the guidewire. There are certain disadvantages and further refinements must be developed to establish transcatheter electrocoagulation as a useful clinical technique for vessel occlusion.
Animals↗
Transcatheter electrocoagulation: experimental evaluation of the anode.
Transcatheter electrocoagulation using direct current has been shown to be an effective method for vessel occlusion. To date, the stainless steel anode has not been entirely satisfactory. Thus, an evaluation of bipolar platinum electrodes and a comparison of monopolar platinum and stainless steel electrodes have been performed. Experimental results have shown that both monopolar and bipolar platinum electrodes caused perforation in most cases. At the present time, we have not found a satisfactory replacement for the unipolar stainless steel anode.
Animals↗
Effect of increasing current and decreasing blood flow for transcatheter electrocoagulation (TCEC).
Arterial occlusion by direct-current transcatheter electrocoagulation (TCEC) has been developed experimentally and used successfully in clinical situations. The major shortcoming of the technique has been the lengthy time necessary for occlusion of larger arteries. In the present study we attempted to decrease the time necessary for TCEC occlusion of the renal and femoral arteries of heparinized mongrel dogs. The results showed that the occlusion time could be significantly decreased, either by increasing the TCEC current from 15 ma to 30 or 60 ma, or by using a Meditech balloon catheter to occlude the artery during TCEC. The combination of higher current and simultaneous balloon occlusion consistently produced permanent occlusion of arteries up to 7 mm in diameter in 15 minutes or less. Balloon occlusion with TCEC is significantly faster than without this modification and makes the technique of TCEC more applicable for human use and for continued experimental study than any previous refinements.
Animals↗
Characterization of human serum dipeptidyl peptidase IV (CD26) and analysis of its autoantibodies in patients with rheumatoid arthritis and other autoimmune diseases.
OBJECTIVES: To assess the serum levels, specific activity and other characteristics of dipeptidylpeptidase IV (DPP IV/CD26), an ectoenzyme that plays a critical role in the modulation and expression of autoimmune and inflammatory diseases, from patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), primary Sjögren syndrome (SS) and normal controls. To study the possible underlying molecular basis if significant differences were found. METHODS: Serum DPP IV was purified by ion-exchange and affinity chromatography techniques and its specific activity and sera levels were determined by an enzyme-linked assay (ELISA). The enzyme was further analyzed for its sialic acid content, its adenosine deaminase binding capacity and its electrophoretic mobility. The levels of circulating IgA, IgG, and IgM anti-DPP IV autoantibodies were determined by an ELISA technique. RESULTS: The median serum levels of DPP IV in RA patients was similar to controls (0.85 microg/ml versus 1.03 microg/ml, p = n.s.); in SLE and SS patients the enzyme serum levels were reduced to nearly one half of controls (p < 0.001). DPP IV specific activity was significantly reduced in serafrom RA patients when compared with those of SLE, SS and normal sera (12.24 versus 16.5, 19.69 and 16.34 mol pNA x 10(-4)/min/mol respectively, p < 0.005). Both RA and SLE enzymes were hypersialylated, but only RA DPP IV augmented its specific activity to close to control values after desialylation with V. cholerae neuraminidase. Sera from all patient groups contained anti-DPP IV autoantibodies, but only those of the IgA isotype were significantly higher than those found in normal subjects. CONCLUSION: The specific activity of serum DPP IV was decreased only in RA patients, although its levels were similar to normal controls. While both RA and SLE DPP IV were hypersialylated, desialylation restored the specific activity only of RA DPP IV. This finding suggests that different specific glycosylation sites in the enzyme might be involved as the underlying mechanism of the decreased enzyme specific activity of RA patients. The differences in DPP IV levels observed between RA and SLE patients seem to reflect a different status of T cell activation in both diseases.
Arthritis, Rheumatoid↗
Behçet's disease patients present high levels of deglycosylated anti-lipoteichoic acid IgG and high IL-8 production after lipoteichoic acid stimulation.
OBJECTIVES: Lipoteichoic acid (LTA), induces some of the clinical symptoms of Behçet's disease (BD) in a rat animal model. These results led to the hypothesis that LTA may also trigger BD in humans. We investigated the humoral and cellular immune response against LTA and lipopolysaccharide (LPS) in patients with BD, and compared these responses with those of patients with active chronic oral ulcers (OU) and normal controls. METHODS: Samples were obtained from 12 active BD, 12 inactive BD, 12 active OU and 12 normal controls. Anti-LTA, anti-LPS antibodies levels and the capacity of immune complexes anti-LTA IgG-LTA to activate complement were studied. Exposed mannose residues in anti-LTA IgG were analyzed in the four groups. The interleukin-8 (IL-8) production by peripheral blood mononuclear cells cultures after LTA and LPS stimulation was also studied in all groups. RESULTS: The capacity to bind mannan binding protein (MBP) of anti-LTA IgGs was significantly higher in BD and active OU patients relative to normal controls (p < 0.001). However, only active BD patients generated significantly higher levels of C5a than controls (p < 0.0001). The IgGs purified from the sera of BD patients showed a high specificity for LTA from Streptococcus sanguis or Streptococcus faecalis. LTA also stimulates the secretion of IL-8 in peripheral blood mononuclear cells isolated from active BD patients. Anti-LPS IgA and IgG titers were significantly higher only in active OU patients relative to normal controls (p < 0.0018). CONCLUSION: These results suggest a mechanism involving LTA from streptococci in the pathogenesis of BD.
Adult↗
Experimental pulmonary infarction in dogs: a comparison of chest radiography and computed tomography.
Transcatheter electrocoagulation of the pulmonary artery was used to successfully create experimental pulmonary infarcts in 15 to 16 dogs. The animals were evaluated from one to 13 weeks by chest radiography, computed tomography (CT), angiography, and pathologic examination. The abnormal densities in the dogs' lungs cleared in two to three weeks. The majority of the chest radiographs were normal in two weeks, and all were normal after three weeks. Prior to sacrifice, CT showed abnormal densities in the lungs in only two of eight animals. CT proved to be more sensitive than chest radiography for showing the densities in the lungs due to pulmonary infarction.
Angiography↗