One class of theoretical accounts of associative learning suggests that reinforcers are processed according to learning rules that minimize the predictive error between the expected strength of future reinforcement and its actual strength. The omission of reinforcement in a situation where it is expected leads to inhibitory learning of stimuli indicative for such a violation of the prediction. There are, however, results indicating that inhibitory learning can also be induced by other mechanisms. Here, we present data from olfactory reward conditioning in honeybees that show that (1) one- and multiple-trial backward conditioning results in conditioned inhibition (CI); (2) the inhibition is maximal for a 15-sec interval between US and CS; (3) there is a nonmonotonic dependency on the degree of CI from the US-CS interval during backward pairing; and (4) the prior association of context stimuli with reinforcement is not necessary for the development of CI. These results cannot be explained by models that only minimize a prediction error. Rather, they are consistent with models of associative learning that, in addition, assume that learning depends on the temporal overlap of a CS with two processes, a fast excitatory and a slow inhibitory one, both evoked by a reinforcer. The fmdings from this behavioral analysis of reinforcement processing are compared with the known properties of an individual, identified neuron involved in reinforcement processing in the bee brain, to further understand the mechanisms underlying predictive reward learning.

Animals↗

PubMedDate not supplied

Induction of pre-transplant Epstein-Barr virus (EBV) infection by donor blood transfusion in EBV-seronegative recipients may reduce risk of post-transplant lymphoproliferative disease in adolescent renal transplant patients: report of two cases.

BACKGROUND: Post-transplant lymphoproliferative disease (PTLD) is a life-threatening complication following organ transplantation. The greatest risk is seen in Epstein-Barr virus (EBV)-seronegative patients receiving allografts from EBV-seropositive donors. We demonstrate a new approach of pre-transplant prophylaxis of EBV-related PTLD, suggesting that, prior to living-related renal transplantation, blood transfusion from an EBV-seropositive donor to an EBV-seronegative recipient could induce primary EBV infection in the recipient, developing EBV immunity and decreasing risk of PTLD. METHODS: Recipients underwent weekly donor-specific blood transfusion (3 x 100 mL) before transplantation. EBV-mRNA expression, viral load, serological tests, and clinical signs of EBV infection were assessed following blood transfusion. RESULTS: We explored a new approach in 2 young EBV-seronegative renal allograft recipients. Both patients developed primary EBV infection following blood transfusion before transplantation and showed symptom-free seroconversion post-transplantation without persistent EBV activation. There were no signs of PTLD during 5-year follow-up. CONCLUSIONS: A new effective and inexpensive approach is suggested for development of EBV immunity and probably for prophylaxis of EBV-associated PTLD.

Adolescent↗

PubMedDate not supplied

Multiple sites of associative odor learning as revealed by local brain microinjections of octopamine in honeybees.

In a classical conditioning procedure, honeybees associate an odor with sucrose resulting in the capacity of the odor to evoke an appetitive response, the extension of the proboscis (PER). Here, we study the effects of pairing an odor with injections of octopamine (OA) as a substitute for sucrose into three putative brain sites of odor/sucrose convergence. OA injected into the mushroom body (MB) calyces or the antennal lobe but not the lateral protocerebral lobe produces a lasting, pairing-specific enhancement of PER. During pairings, OA injected into the MB calyces results in an additional pairing-specific effect, because it does not lead to an acquisition but a consolidation after conditioning. These results suggest that the neuromodulator OA has the capacity of inducing associative learning in an insect brain. Moreover, they suggest the antennal lobes and the calyces as at least partially independent sites of associating odors that may contribute differently to learning and memory consolidation.

Animals↗

PubMedDate not supplied

How process enterprises really work.

Many companies have succeeded in reengineering their core processes, combining related activities from different departments and cutting out ones that don't add value. Few, though, have aligned their organizations with their processes. The result is a form of cognitive dissonance as the new, integrated processes pull people in one direction and the old, fragmented management structures pull them in another. That's not the way it has to be. In recent years, forward-thinking companies like IBM, Texas Instruments, and Duke Power have begun to make the leap from process redesign to process management. They've appointed some of their best managers to be process owners, giving them real authority over work and budgets. They've shifted the focus of their measurement and compensation systems from unit goals to process goals. They've changed the way they assign and train employees, emphasizing whole processes rather than narrow tasks. They've thought carefully about the strategic trade-offs between adopting uniform processes and allowing different units to do things their own way. And they've made subtle but fundamental cultural changes, stressing teamwork and customers over turf and hierarchy. These companies are emerging from all those changes as true process enterprises--businesses whose management structures are in harmony, rather than at war, with their core processes. And their organizations are becoming much more flexible, adaptive, and responsive as a result.

Evaluation Studies as Topic↗

PubMedDate not supplied

Chlamydial rRNA in the joints of patients with Chlamydia-induced arthritis and undifferentiated arthritis.

Synovial fluid and synovial membrane specimens of 11 patients with Chlamydia-induced arthritis (CIA), 24 patients with undifferentiated arthritis (UndA), 4 patients with post-enteritic reactive arthritis, 3 patients with Lyme arthritis and 9 patients with rheumatoid arthritis were investigated for the presence of Chlamydia trachomatis (C. trachomatis). A single stranded DNA-probe was used for nucleic acid hybridization with ribosomal RNA (rRNA) from C. trachomatis. In 4 patients (CIA = 1, UndA = 3) chlamydial rRNA was found in the synovial fluid. In one additional patient (CIA) the specimen of a synovial membrane biopsy was positive for chlamydial rRNA. The detection of intra-articular chlamydial rRNA is discussed as an indicator for the presence of viable Chlamydiae in inflamed joints.

Arthritis, Infectious↗

PubMedDate not supplied

A ritual of remembrance.

Explore the source record for details and available documents.

Child↗

PubMedDate not supplied

[Detection of endotoxin in synovial tissue of patients with inflammatory-rheumatic diseases].

The etiology of inflammatory rheumatic diseases is unknown. The hypothesis, that bacteriae may play a part in the induction of a rheumatic synovialitis is further substantiated by the detection of Endotoxin (Lipid A) in the synovial membranes of five of eleven patients with early synovitis (disease duration shorter than 6 months) by using anti Lipid A monoclonal antibodies. Endotoxin (Lipid A) is a component of gram-negative bacteriae and Chlamydiae. It is a potent immunogen, and could be the link between infection of the gut or the urogenital system and the rheumatic synovialitis.

Adult↗

PubMedDate not supplied

[Determination of endotoxin in inflammatory rheumatic diseases--the effect of nonsteroidal anti-inflammatory agents on intestinal permeability].

We measured the amount of plasma endotoxin in 95 patients with inflammatory rheumatic diseases (42 with ankylosing spondylitis; 12 with possible ankylosing spondylitis; 41 with rheumatoid arthritis) and in 16 patients with Crohn's disease with a quantitative Limulus assay. Significantly increased mean values were found in inflammatory rheumatic diseases and in Crohn's disease. Between 31% and 50% of the patients had endotoxin values higher than 10 pg/ml--none of the controls had such values. Patients on regular treatment with NSAIDS had higher amounts of endotoxin again. From our results we discuss an intestinal involvement in inflammatory rheumatic diseases. An inflammation of the gut with an increased permeability seems to be responsible for the raised plasma endotoxin levels compared to healthy controls. NSAIDs probably contribute to the increased permeability of the gut.

Adult↗

PubMedDate not supplied

Occupational health.

Explore the source record for details and available documents.

Certification↗

PubMedDate not supplied

[NMR tomography of the knee joint in patients with rheumatic joint diseases].

Twenty patients with rheumatoid gonarthritis were examined in a NMR tomograph with a 0.2 tesla resistive magnet. Synovial effusions were seen in 18 cases and thickening of the synovium in 15 cases. Discrimination between synovial fluid and synovium was gained by different NMR signals from various spin-echo sequences. In demonstrating a thickened synovium NMR tomography enables the depiction of inflammation inside the joint in earlier stages of illness than is possible with bone erosion detection from X-ray photographs.

Adult↗