353 research outputs found
Surprise... Surprise..., An Empirical Investigation on How Surprise is Connected to Customer Satisfaction
This research investigates the specific influence of the emotion ofsurprise on customer transaction-specific satisfaction. Four empiricalstudies-two field studies (a diary study and a cross section survey)and two experiments-were conducted. The results show that surprisepositively [negatively] influences satisfaction directly andindirectly (via the amplification of positive [negative] emotions),even when disconfirmation is taken into account in the model. Theamplification property of surprise and the How-do-I-feel-about-it?heuristic are believed to explain this influence. Some results alsoshow that surprised customers display higher levels of satisfactionand dissatisfaction than non surprised customers.satisfaction;experiment;delight;disconfirmation;surprise
“Surprise Gift” Purchases of Small Electric Appliances: A Pilot Study
Understanding decision-making processes for gifts is of strategic importance for companies selling small electrical appliances as gifts account for a large part of their sales. Among all gifts, the ones that are surprising are the most valued by recipients. However, research about decision-making processes involved in surprise gift purchases is lacking. This article shows, for example, that design and money back guarantees are more important for the purchase of surprise gifts than other gifts. The brand name, however, appears to be less important. Also, surprise gifts are more often bought on the spot, without extended information search (similar to impulse purchases)
Strategic ambiguity in minority targeting
Ambiguous cues in advertising offer companies the chance to
reach multiple consumer segments with the one economical
campaign. ‘Purposeful polysemy’ can indeed be an effective
strategy – but it may not always deliver what it promises
Surprise... Surprise..., An Empirical Investigation on How Surprise is Connected to Customer Satisfaction
This research investigates the specific influence of the emotion of
surprise on customer transaction-specific satisfaction. Four empirical
studies-two field studies (a diary study and a cross section survey)
and two experiments-were conducted. The results show that surprise
positively [negatively] influences satisfaction directly and
indirectly (via the amplification of positive [negative] emotions),
even when disconfirmation is taken into account in the model. The
amplification property of surprise and the How-do-I-feel-about-it?
heuristic are believed to explain this influence. Some results also
show that surprised customers display higher levels of satisfaction
and dissatisfaction than non surprised customers
Go configure: the mix of purchasing practices to choose for your supply base
Purchasing and supply management professionals recognize the value of aggressive transactional sourcing, as well as of having cooperative relationships with suppliers. But what mix of transactional and relational purchasing are organizations using, and which should they use? A novel instrument is developed to measure organizations’ use of transaction purchasing, electronic purchasing, interactive purchasing, and network purchasing. Four mixes of practices are identified and labeled “transactional,” “interpersonal dyadic,” “interpersonal network,” and “integrative relational” configurations. Organizations using an integrative relational configuration generally outperform others. Irrespective of configuration, organizations use more interactive and network purchasing with suppliers of direct inputs but more transaction purchasing with suppliers of indirect inputs
Antigenic variation in <i>Trypanosoma brucei</i>: joining the DOTs
African trypanosomes, such as <i>Trypanosoma brucei</i>, are protistan parasites that cause sleeping sickness. Though first described more than a century ago, trypanosomes remain a blight on the health of the human population and on the economy of sub-Saharan Africa. <i>T. brucei</i> replicates in the bloodstream of infected mammals and traverses the blood-brain barrier to enter the central nervous system in the late, frequently fatal, stages of the disease. Because of its extracellular lifestyle, <i>T. brucei</i> is continuously exposed to antibody challenge. To circumvent this, the parasite uses antigenic variation of a surface protein named the variant surface glycoprotein (VSG). Around 107 VSG molecules are expressed on the parasite's cell surface, creating a dense coat that prevents adaptive immunity from detecting or accessing invariant antigens. However, antibodies against the expressed VSG are generated, and periodic switches to an immunologically distinct VSG coat are necessary for parasite survival. Such switches are pre-emptive of the immune response and contribute to the pattern of trypanosome growth seen in an infected host (Figure 1): parasite numbers increase, but then drop as VSG-specific antibodies are raised by the host. Cells that have switched to another VSG coat survive this killing and seed the outgrowth of a subsequent peak of parasites, which is again decimated by anti-VSG immune killing. As a survival strategy, antigenic variation succeeds by prolonging the time that the parasite
Differences between <i>Trypanosoma brucei gambiense</i> groups 1 and 2 in their resistance to killing by Trypanolytic factor 1
<p><b>Background:</b> The three sub-species of <i>Trypanosoma brucei</i> are important pathogens of sub-Saharan Africa. <i>T. b. brucei</i> is unable to infect humans due to sensitivity to trypanosome lytic factors (TLF) 1 and 2 found in human serum. <i>T. b. rhodesiense</i> and <i>T. b. gambiense</i> are able to resist lysis by TLF. There are two distinct sub-groups of <i>T. b. gambiense</i> that differ genetically and by human serum resistance phenotypes. Group 1 <i>T. b. gambiense</i> have an invariant phenotype whereas group 2 show variable resistance. Previous data indicated that group 1 <i>T. b. gambiense</i> are resistant to TLF-1 due in-part to reduced uptake of TLF-1 mediated by reduced expression of the TLF-1 receptor (the haptoglobin-hemoglobin receptor (<i>HpHbR</i>)) gene. Here we investigate if this is also true in group 2 parasites.</p>
<p><b>Methodology:</b> Isogenic resistant and sensitive group 2 <i>T. b. gambiense</i> were derived and compared to other T. brucei parasites. Both resistant and sensitive lines express the <i>HpHbR</i> gene at similar levels and internalized fluorescently labeled TLF-1 similar fashion to <i>T. b. brucei</i>. Both resistant and sensitive group 2, as well as group 1 <i>T. b. gambiense</i>, internalize recombinant APOL1, but only sensitive group 2 parasites are lysed.</p>
<p><b>Conclusions:</b> Our data indicate that, despite group 1 <i>T. b. gambiense</i> avoiding TLF-1, it is resistant to the main lytic component, APOL1. Similarly group 2 <i>T. b. gambiense</i> is innately resistant to APOL1, which could be based on the same mechanism. However, group 2 <i>T. b. gambiense</i> variably displays this phenotype and expression does not appear to correlate with a change in expression site or expression of <i>HpHbR</i>. Thus there are differences in the mechanism of human serum resistance between <i>T. b. gambiense</i> groups 1 and 2.</p>
The TgsGP gene is essential for resistance to human serum in Trypanosoma brucei gambiense
Trypanosoma brucei gambiense causes 97% of all cases of African sleeping sickness, a fatal disease of sub-Saharan Africa. Most species of trypanosome, such as T. b. brucei, are unable to infect humans due to the trypanolytic serum protein apolipoprotein-L1 (APOL1) delivered via two trypanosome lytic factors (TLF-1 and TLF-2). Understanding how T. b. gambiense overcomes these factors and infects humans is of major importance in the fight against this disease. Previous work indicated that a failure to take up TLF-1 in T. b. gambiense contributes to resistance to TLF-1, although another mechanism is required to overcome TLF-2. Here, we have examined a T. b. gambiense specific gene, TgsGP, which had previously been suggested, but not shown, to be involved in serum resistance. We show that TgsGP is essential for resistance to lysis as deletion of TgsGP in T. b. gambiense renders the parasites sensitive to human serum and recombinant APOL1. Deletion of TgsGP in T. b. gambiense modified to uptake TLF-1 showed sensitivity to TLF-1, APOL1 and human serum. Reintroducing TgsGP into knockout parasite lines restored resistance. We conclude that TgsGP is essential for human serum resistance in T. b. gambiense
Telomeric expression sites are highly conserved in trypanosoma brucei
Subtelomeric regions are often under-represented in genome sequences of eukaryotes. One of the best known examples of the use of telomere proximity for adaptive purposes are the bloodstream expression sites (BESs) of the African trypanosome Trypanosoma brucei. To enhance our understanding of BES structure and function in host adaptation and immune evasion, the BES repertoire from the Lister 427 strain of T. brucei were independently tagged and sequenced. BESs are polymorphic in size and structure but reveal a surprisingly conserved architecture in the context of extensive recombination. Very small BESs do exist and many functioning BESs do not contain the full complement of expression site associated genes (ESAGs). The consequences of duplicated or missing ESAGs, including ESAG9, a newly named ESAG12, and additional variant surface glycoprotein genes (VSGs) were evaluated by functional assays after BESs were tagged with a drug-resistance gene. Phylogenetic analysis of constituent ESAG families suggests that BESs are sequence mosaics and that extensive recombination has shaped the evolution of the BES repertoire. This work opens important perspectives in understanding the molecular mechanisms of antigenic variation, a widely used strategy for immune evasion in pathogens, and telomere biology
Trypanosome Lytic Factor, an Antimicrobial High-Density Lipoprotein, Ameliorates Leishmania Infection
Innate immunity is the first line of defense against invading microorganisms. Trypanosome Lytic Factor (TLF) is a minor sub-fraction of human high-density lipoprotein that provides innate immunity by completely protecting humans from infection by most species of African trypanosomes, which belong to the Kinetoplastida order. Herein, we demonstrate the broader protective effects of human TLF, which inhibits intracellular infection by Leishmania, a kinetoplastid that replicates in phagolysosomes of macrophages. We show that TLF accumulates within the parasitophorous vacuole of macrophages in vitro and reduces the number of Leishmania metacyclic promastigotes, but not amastigotes. We do not detect any activation of the macrophages by TLF in the presence or absence of Leishmania, and therefore propose that TLF directly damages the parasite in the acidic parasitophorous vacuole. To investigate the physiological relevance of this observation, we have reconstituted lytic activity in vivo by generating mice that express the two main protein components of TLFs: human apolipoprotein L-I and haptoglobin-related protein. Both proteins are expressed in mice at levels equivalent to those found in humans and circulate within high-density lipoproteins. We find that TLF mice can ameliorate an infection with Leishmania by significantly reducing the pathogen burden. In contrast, TLF mice were not protected against infection by the kinetoplastid Trypanosoma cruzi, which infects many cell types and transiently passes through a phagolysosome. We conclude that TLF not only determines species specificity for African trypanosomes, but can also ameliorate an infection with Leishmania, while having no effect on T. cruzi. We propose that TLFs are a component of the innate immune system that can limit infections by their ability to selectively damage pathogens in phagolysosomes within the reticuloendothelial system
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