Response allocation to concurrent fixed-ratio reinforcement schedules with work requirements by adults with mental retardation and typical preschool children.

The present experiments examined the effect of work requirements in combination with reinforcement schedule on the choice behavior of adults with mental retardation and preschool children. The work requirements of age-appropriate tasks (i.e., sorting silverware, jumping hurdles, tossing beanbags) were manipulated. Participants were presented with their choice of two response options for each trial that varied simultaneously on both work requirement and reinforcement schedule. Results showed that when responding to both choices occurred on the same reinforcement schedule, participants allocated most of their responses to the option with the easier work requirement. When the response option requiring less work was on a leaner reinforcement schedule, most participants shifted their choice to exert more work. There were individual differences across participants regarding their pattern of responding and when they switched from the lesser to the greater work requirement. Data showed that participants' responding was largely controlled by the reinforcement received for responding to each level of work. Various conceptualizations regarding the effects of work requirements on choice behavior are discussed.

D-dimer tests detect both plasmin and neutrophil elastase derived split products.

Both plasmin and elastase, a protease released from neutrophil granulocytes, are known to degrade fibrin(ogen). This raises the possibility that elevated plasma levels of split products such as D-dimer may in part result from elastase action. After incubation in vitro of fibrinogen and fibrin clots with elastase, a clearcut increase of D-dimer immunoreactivity was demonstrated by two commercial ELISA kits. In the plasma of 79 patients with inflammatory bowel disease, D-dimer values measured by one of the ELISA kits were correlated significantly not only with markers of thrombin and plasmin activation, but also with elastase-alpha 1-antitrypsin complexes (r = 0.3555; P = 0.014). Thus, the findings of this study suggest that indeed the D-dimer levels in patients with inflammatory disorders are influenced by neutrophil elastase. New tests discriminating effects of activated haemostasis from proteolysis by neutrophil enzymes might be helpful in differential diagnosis and monitoring of therapy.

Thrombomodulin and ristocetincofactor in homocystinuria: a study in two siblings.

Homocystinuria due to cystathionine-beta-synthase deficiency (CBS-def-HOCY) initially often presents with vascular disorders, e.g. thromboembolic events. The measurement of vascular endothelial markers in plasma could help to assess endothelial damage. We determined von Willebrand factor (measured as Ristocetincofactor, RiCoF) and thrombomodulin (TM), two endothelial cell markers to our knowledge not measured systematically before in homocystinuria patients in a longitudinal study of two homocystinuric patients: Patient1 with thromboembolic disease and his asymptomatic sister, patient2. Before start of therapy in patient 1, TM and RiCoF levels both were increased. In patient 2 a moderately elevated RiCoF and a normal level of TM were found. Vitamin therapy with 15 mg folate and 600 mg pyridoxine per day led to almost complete normalization of amino acids in urine and plasma, and complete normalization of RiCoF and TM levels in both patients. Thus, TM and RiCoF elevations demonstrate that CBS-def-HOCY leads to endothelial cell damage, which resolved under vitamin therapy in the patients studied.

Coagulation factors and markers of activation of coagulation in homocystinuria (HOCY): a study in two siblings.

Homocystinuria due to cystathionine-beta-synthase deficiency (CBS-def-HOCY) initially often present with thromboembolic events. In most cases in which coagulation factors have been analysed, a deficiency of AT-IIIc and factor VIIc has been reported, the cause of which has not been elucidated. Activation of coagulation with consumption of coagulation factors has been postulated as the mechanism. This paper reports a longitudinal study of two patients: patient 1 with thromboembolic disease and his asymptomatic sister, patient 2. Before start of therapy in patient 1, a reduction of FVIIc, other coagulation factors, and AT-IIIc was found. Markers of activation of coagulation (F1 + 2, TAT, FM, D-dimers) were elevated only in patient 1, and only at the time of thrombotic complications. In patient 2 reduced levels of FVIIc and other coagulation proteins, and a low borderline AT-IIIc level was found. Thus, in the two patients, sustained activation of coagulation can be reasonably excluded to be the cause of low levels of coagulation proteins. Vitamin therapy with 15 mg folate and 600 mg pyridoxine per day led to almost complete normalization of amino acids in urine and plasma. Thrombosis has not recurred to date. FVIIc and the other coagulation proteins and AT-IIIc increased in parallel with the biochemical remission. Direct inhibition of the activity of AT-III and coagulation factor VIII and other factors by homocysteine was attempted in vitro but could not be shown at HC concentrations known to occur in the plasma of HOCY patients. Therefore, in these patients, deficient synthesis of coagulation factors and AT-III due to a disturbance of amino acid metabolism is still the most probable explanation for the observed low levels.

Optimizing electroporation parameters for a variety of human hematopoietic cell lines.

The parameters affecting electroporation of four human hematopoietic cell lines were investigated. The optimal conditions for electroporation are described for both transient and stable expression of foreign genes. A correlation exists between the levels of transient gene expression and stable transfection frequency. In addition, linear DNA yields higher stable transfection frequencies than supercoiled DNA. The cumulative results indicate that electroporation is a simple and useful method for obtaining transient and stable expression of foreign genes in human hematopoietic cells.

Adeno-associated virus: a vector system for efficient introduction and integration of DNA into a variety of mammalian cell types.

Adeno-associated virus (AAV) is a single-stranded DNA parvovirus that is dependent on adenovirus or herpesvirus for reproductive functions. We describe the construction of recombinant AAV vectors containing the chloramphenicol acetyltransferase gene or the neomycin phosphotransferase gene. These vectors carried their respective genes into a wide variety of cell types, including primary skin fibroblasts and hematopoietic cells. Infection efficiencies varied with cell type and ranged up to 3.0%. Coinfection of two different recombinant viruses was also used to introduce two different sequences simultaneously into a given cell. Finally, methods for obtaining recombinant AAV vectors with minimal contamination of wild-type virus are described. These various attributes of AAV vectors make them a viable DNA transduction system.

Inducible gene expression from multiple promoters by the tumor-promoting agent, PMA.

Phorbol ester tumor promoters affect a broad scope of changes in mammalian cells. This report describes the activation of expression of an introduced chloramphenicol acetyltransferase (CAT) reporter gene by the phorbol ester, phorbol 12-myristate 13-acetate (PMA), in a variety of fibroblast and hematopoietic cell lines. PMA-mediated activation appears to be promoter region specific, yet widespread. Enhanced gene expression is observed for four out of five promoter systems tested, and, in some cases, is dependent on the cellular environment. Further experiments indicate that PMA mediates elevated gene expression by rapidly increasing steady state levels of CAT mRNA. The broad range of promoters affected by PMA may help explain the high potency of this agent in tumor production.

The proteinase inhibitor complexes (antithrombin III-thrombin, alpha 2antiplasmin-plasmin and alpha 1antitrypsin-elastase) in septicemia, fulminant hepatic failure and cardiac shock: value for diagnosis and therapy control in DIC/F syndrome.

Thrombin (Thr), plasmin (Pl) and elastase (ELP) are serine proteinases which are quickly inactivated by their specific inhibitors (AT III, alpha 2AP, alpha 1AT), if intravascular activation of coagulation and fibrinolytic system or if release from PMN granulocytes by different stimuli (F.I., endotoxin, activated factor XII, a.o.) occurs. The immunological determination of the developing proteinase inhibitor complexes (PIC) AT III-Thr, alpha 2AP-Pl and alpha 1AT-ELP gives information as to whether intravascular coagulation, hyperfibrinolysis or unspecific proteolysis induced by elastase have taken place. Despite the high antiprotease activity in the plasma the a.m. serine proteinases may exert their proteolytic activity towards their specific substrates in vivo. In infectious diseases, fulminant hepatic failure and cardiac shock a complex consumption of coagulation factors and inhibitors may cause severe coagulation defects, microcirculatory disturbances and bleeding tendency. The PICs behaviour was determined in more than 80 patients with infectious diseases, in 5 patients with fulminant hepatic failure (FHF) and 7 patients with cardiac shock. Only in infectious diseases, mainly in septic complications, and septic complications during FHF and cardiac shock, are alpha 1AT-ELP levels found to be highly elevated. After cardiac shock, in FHF and in infectious diseases coagulation and fibrinolysis may additionally be activated. In this case AT III-Thr and alpha 2AP-Pl complexes could be detected in the patients plasma. This indicates that intravascular coagulation and hyperfibrinolysis has additionally taken place. To prevent bleeding complications a replacement therapy with plasma derivatives (AT III, plasminogen concentrate, PPSB and FFP) has been successfully performed in several patients with septic complications and in the 5 patients with FHF and the 7 patients with cardiac shock. No bleeding complication occurred, and the haemostatic balance could be maintained in the treated patients. AT III replacement therapy is necessary to stop DIC, PPSB improves severe coagulation defects, only FFP may additionally provide alpha 1AT, alpha 2AP and factor V. In acute renal failure sometimes plasminogen replacement is necessary to maintain a normal activity of the fibrinolytic system. The complex consumption of coagulation proteins in infectious diseases, FHF and cardiac shock cannot successfully be treated with an anticoagulant such as heparin alone.

The clinical significance of alpha 1-antitrypsin-elastase (alpha 1AT-ELP) and alpha 2-antiplasmin-plasmin (alpha 2AP-PL) complexes for the differentiation of coagulation protein turnover: indications for plasma protein substitution in patients with septicaemia.

In inflammation, particularly in septicaemia, complex coagulation disorders may lead to a dangerous haemorrhagic diathesis. The conventional concept for this syndrome called DIC implicates the occurrence of active thrombin in the circulation, which may be followed by hyperfibrinolysis due to plasmin formation. In this study data are presented suggesting an important role for a third proteolytic system, granulocytic elastase. The complexes of plasmin and elastase with their specific inhibitors, alpha 2-antiplasmin-plasmin (alpha 2AP-PI) and alpha 1-antitrypsin-elastase (alpha 1AT-ELP) were determined immunologically. The alpha 1AT-ELP appears mainly in gram-negative septicaemia, particularly in meningococcal disease. The estimation of alpha 2AP-PI and alpha 1AT-ELP, together with a method for the detection of the antithrombin III--thrombin complex which remains to be established, is a suitable tool for for the differential diagnosis of the consumption of coagulation proteins. The assumption that at least three proteolytic systems participate in the development of the haemorrhagic diathesis during inflammation leads to the concept of a broad, comprehensive substitution therapy with e.g. concentrates of AT III, PPSB, or fresh frozen plasma. The aim of this treatment is to replace not only the consumed procoagulatory factors, but also the lacking inhibitors in order to control this "abnormal proteolysis syndrome".