Structure-activity relationship of 2,4-D correlates auxinic activity with the induction of somatic embryogenesis in Arabidopsis thaliana.

2,4-dichlorophenoxyacetic acid (2,4-D) is a synthetic analogue of the plant hormone auxin that is commonly used in many in vitro plant regeneration systems, such as somatic embryogenesis (SE). Its effectiveness in inducing SE, compared to the natural auxin indole-3-acetic acid (IAA), has been attributed to the stress triggered by this compound rather than its auxinic activity. However, this hypothesis has never been thoroughly tested. Here we used a library of forty 2,4-D analogues to test the structure-activity relationship with respect to the capacity to induce SE and auxinic activity in Arabidopsis thaliana. Four analogues induced SE as effectively as 2,4-D and 13 analogues induced SE but were less effective. Based on root growth inhibition and auxin response reporter expression, the 2,4-D analogues were classified into different groups, ranging from very active to not active auxin analogues. A halogen at the 4-position of the aromatic ring was important for auxinic activity, whereas a halogen at the 3-position resulted in reduced activity. Moreover, a small substitution at the carboxylate chain was tolerated, as was extending the carboxylate chain with an even number of carbons. The auxinic activity of most 2,4-D analogues was consistent with their simulated TIR1-Aux/IAA coreceptor binding characteristics. A strong correlation was observed between SE induction efficiency and auxinic activity, which is in line with our observation that 2,4-D-induced SE and stress both require TIR1/AFB auxin co-receptor function. Our data indicate that the stress-related effects triggered by 2,4-D and considered important for SE induction are downstream of auxin signalling.

Probing Peptidoglycan Synthesis in the Gut Commensal Akkermansia muciniphila with Bioorthogonal Chemical Reporters.

Our gut microbiota directly influences human physiology in health and disease. The myriad of surface glycoconjugates in both the bacterial cell envelope and our gut cells dominate the microbiota-host interface and play a critical role in host response and microbiota homeostasis. Among these, peptidoglycan is the basic glycan polymer offering the cell rigidity and a basis on which many other glycoconjugates are anchored. To directly study peptidoglycan in gut commensals and obtain the molecular insight required to understand their functional activities we need effective techniques like chemical probes to label peptidoglycan in live bacteria. Here we report a chemically guided approach to study peptidoglycan in a key mucin-degrading gut microbiota member of the Verrucomicrobia phylum, Akkermansia muciniphila. Two novel non-toxic tetrazine click-compatible peptidoglycan probes with either a cyclopropene or isonitrile handle allowed for the detection and imaging of peptidoglycan synthesis in this intestinal species.

Sweet impersonators: Molecular mimicry of host glycans by bacteria.

All bacteria display surface-exposed glycans that can play an important role in their interaction with the host and in select cases mimic the glycans found on host cells, an event called molecular or glycan mimicry. In this review, we highlight the key bacteria that display human glycan mimicry and provide an overview of the involved glycan structures. We also discuss the general trends and outstanding questions associated with human glycan mimicry by bacteria. Finally, we provide an overview of several techniques that have emerged from the discipline of chemical glycobiology, which can aid in the study of the composition, variability, interaction and functional role of these mimicking glycans.

Selective Exoenzymatic Labeling of Lipooligosaccharides of Neisseria gonorrhoeae with α2,6-Sialoside Analogues.

The interactions between bacteria and their host often rely on recognition processes that involve host or bacterial glycans. Glycoengineering techniques make it possible to modify and study the glycans on the host's eukaryotic cells, but only a few are available for the study of bacterial glycans. Here, we have adapted selective exoenzymatic labeling (SEEL), a chemical reporter strategy, to label the lipooligosaccharides of the bacterial pathogen Neisseria gonorrhoeae, using the recombinant glycosyltransferase ST6Gal1, and three synthetic CMP-sialic acid derivatives. We show that SEEL treatment does not affect cell viability and can introduce an α2,6-linked sialic acid with a reporter group on the lipooligosaccharides by Western blot, flow cytometry and fluorescent microscopy. This new bacterial glycoengineering technique allows for the precise modification, here with α2,6-sialoside derivatives, and direct detection of specific surface glycans on live bacteria, which will aid in further unravelling the precise biological functions of bacterial glycans.

Role of Toll-Like Receptor 5 (TLR5) in Experimental Melioidosis.

The Gram-negative intracellular pathogen Burkholderia pseudomallei is the causative agent of melioidosis, an important cause of sepsis in Southeast Asia. Recognition of pathogen-associated molecular patterns by Toll-like receptors (TLRs) is essential for an appropriate immune response during pathogen invasion. In patients with melioidosis, TLR5 is the most abundantly expressed TLR, and a hypofunctional TLR5 variant has been associated with improved survival. Here, we studied the functional role of TLR5 and its ligand flagellin in experimental melioidosis. First, we observed differential TLR5 expression in the pulmonary and hepatic compartments upon infection with B. pseudomallei Next, we found that B. pseudomallei-challenged TLR5-deficient (Tlr5-/- ) mice were more susceptible to infection than wild-type (WT) mice, as demonstrated by higher systemic bacterial loads, increased organ injury, and impaired survival. Lung bacterial loads were not different between the two groups. The phenotype was flagellin independent; no difference in in vivo virulence was observed for the flagellin-lacking mutant MM36 compared to the wild-type B. pseudomallei strain 1026b. Tlr5-/- mice showed a similar impaired antibacterial defense when infected with MM36 or 1026b. Ex vivo experiments showed that TLR5-deficient macrophages display markedly impaired phagocytosis of B. pseudomallei In conclusion, these data suggest that TLR5 deficiency has a detrimental flagellin-independent effect on the host response against pulmonary B. pseudomallei infection.

Defining the Determinants of Specificity of Plasmodium Proteasome Inhibitors.

The Plasmodium proteasome is an emerging antimalarial target due to its essential role in all the major life cycle stages of the parasite and its contribution to the establishment of resistance to artemisinin (ART)-based therapies. However, because of a similarly essential role for the host proteasome, the key property of any antiproteasome therapeutic is selectivity. Several parasite-specific proteasome inhibitors have recently been reported, however, their selectivity must be improved to enable clinical development. Here we describe screening of diverse libraries of non-natural synthetic fluorogenic substrates to identify determinants at multiple positions on the substrate that produce enhanced selectivity. We find that selection of an optimal electrophilic "warhead" is essential to enable high selectivity that is driven by the peptide binding elements on the inhibitor. We also find that host cell toxicity is dictated by the extent of coinhibition of the human ß2 and ß5 subunits. Using this information, we identify compounds with over 3 orders of magnitude selectivity for the parasite enzyme. Optimization of the pharmacological properties resulted in molecules that retained high potency and selectivity, were soluble, sufficiently metabolically stable and orally bioavailable. These molecules are highly synergistic with ART and can clear parasites in a mouse model of infection, making them promising leads as antimalarial drugs.

A prospective study of the importance of enteric fever as a cause of non-malarial febrile illness in patients admitted to Chittagong Medical College Hospital, Bangladesh.

BACKGROUND: Fever is a common cause of hospital admission in Bangladesh but causative agents, other than malaria, are not routinely investigated. Enteric fever is thought to be common. METHODS: Adults and children admitted to Chittagong Medical College Hospital with a temperature of ≥38.0 °C were investigated using a blood smear for malaria, a blood culture, real-time PCR to detect Salmonella Typhi, S. Paratyphi A and other pathogens in blood and CSF and an NS1 antigen dengue ELISA. RESULTS: We enrolled 300 febrile patients with a negative malaria smear between January and June 2012: 156 children (aged ≤15 years) and 144 adults with a median (interquartile range) age of 13 (5-31) years and median (IQR) illness duration before admission of five (2-8) days. Clinical enteric fever was diagnosed in 52 patients (17.3 %), lower respiratory tract infection in 48 (16.0 %), non-specific febrile illness in 48 (16.0 %), a CNS infection in 37 patients (12.3 %), urinary sepsis in 23 patients (7.7 %), an upper respiratory tract infection in 21 patients (7.0 %), and diarrhea or dysentery in 21 patients (7.0 %). Malaria was still suspected in seven patients despite a negative microscopy test. S. Typhi was detected in blood by culture or PCR in 34 (11.3 %) of patients. Of note Rickettsia typhi and Orientia tsutsugamushi were detected by PCR in two and one patient respectively. Twenty-nine (9 %) patients died during their hospital admission (15/160 (9.4 %) of children and 14/144 (9.7 %) adults). Two of 52 (3.8 %) patients with enteric fever, 5/48 (10.4 %) patients with lower respiratory tract infections, and 12/37 (32.4 %) patients with CNS infection died. CONCLUSION: Enteric fever was confirmed in 11.3 % of patients admitted to this hospital in Bangladesh with non-malaria fever. Lower respiratory tract and CNS infections were also common. CNS infections in this location merit more detailed study due to the high mortality.

The diagnostic accuracy of three rapid diagnostic tests for typhoid fever at Chittagong Medical College Hospital, Chittagong, Bangladesh.

OBJECTIVE: To determine the diagnostic accuracy of three rapid diagnostic tests (RDTs) for typhoid fever in febrile hospitalised patients in Bangladesh. METHODS: Febrile adults and children admitted to Chittagong Medical College Hospital, Bangladesh, were investigated with Bact/Alert(®) blood cultures and real-time PCR to detect Salmonella enterica Typhi and Paratyphi A and assays for Rickettsia, leptospirosis and dengue fever. Acute serum samples were examined with the LifeAssay (LA) Test-it™ Typhoid IgM lateral flow assay detecting IgM antibodies against S. Typhi O antigen, CTKBiotech Onsite Typhoid IgG/IgM Combo Rapid-test cassette lateral flow assay detecting IgG and IgM antibodies against S. Typhi O and H antigens and SD Bioline line assay for IgG and IgM antibodies against S. Typhi proteins. RESULTS: In 300 malaria smear-negative febrile patients [median (IQR) age of 13.5 (5-31) years], 34 (11.3%) had confirmed typhoid fever: 19 positive by blood culture for S. Typhi (three blood PCR positive) and 15 blood culture negative but PCR positive for S. Typhi in blood. The respective sensitivity and specificity of the three RDTs in patients using a composite reference standard of blood culture and/or PCR-confirmed typhoid fever were 59% and 61% for LifeAssay, 59% and 74% for the CTK IgM and/or IgG, and 24% and 96% for the SD Bioline RDT IgM and/or IgG. The LifeAssay RDT had a sensitivity of 63% and a specificity of 91% when modified with a positive cut-off of ≥2+ and analysed using a Bayesian latent class model. CONCLUSIONS: These typhoid RDTs demonstrated moderate diagnostic accuracies, and better tests are needed.

Limited role for ASC and NLRP3 during in vivo Salmonella Typhimurium infection.

BACKGROUND: The inflammasome is an intracellular protein complex triggered by exposure to intracellular pathogens, its components or other endogenous proteins. It leads to the activation of and subsequent release of proinflammatory cytokines such as IL-1ß and IL-18. S. Typhimurium is a Gram-negative intracellular bacterium, which is known to trigger inflammasome assembly via recognition by the cytosolic receptors, NLRP3 and NLRC4 (which act via the adaptor protein, ASC) to induce cell death and cytokine release. We sought to characterize the role of ASC and NLRP3 in two different murine models (typhoid and colitis) of systemic Salmonella infection. RESULTS: Release of the inflammasome cytokine IL-18 was hampered in Asc-/- but not Nlrp3-/- mice (background C57BL/6) during S. Typhimurium infection. Unexpectedly, neither ASC nor NLRP3 played a significant role in host defense against S. Typhimurium infection, as reflected by equal bacterial counts in WT, Asc-/- and Nlrp3-/- mice at all time points, in both the typhoid and colitis models. Proinflammatory cytokine levels (TNF-α, IL-6) and the extent of hepatic and splenic pathology did not differ between groups in the typhoid model. In the colitis model small differences were seen with regard to splenic and hepatic inflammation, although this was IL-18 independent. CONCLUSIONS: IL-18 release was reduced in Asc-/- but not Nlrp3-/- mice during S. Typhimurium infection. Despite this reduction, bacterial counts, cytokine levels and histological inflammation did not differ between wild-type and knockout mice in either model. Our results reveal a limited role for ASC and NLRP3 during in vivo S. Typhimurium infection despite its role in cytokine maturation.

Host-pathogen interaction in invasive Salmonellosis.

Salmonella enterica infections result in diverse clinical manifestations. Typhoid fever, caused by S. enterica serovar Typhi (S. Typhi) and S. Paratyphi A, is a bacteremic illness but whose clinical features differ from other Gram-negative bacteremias. Non-typhoidal Salmonella (NTS) serovars cause self-limiting diarrhea with occasional secondary bacteremia. Primary NTS bacteremia can occur in the immunocompromised host and infants in sub-Saharan Africa. Recent studies on host-pathogen interactions in Salmonellosis using genome sequencing, murine models, and patient studies have provided new insights. The full genome sequences of numerous S. enterica serovars have been determined. The S. Typhi genome, compared to that of S. Typhimurium, harbors many inactivated or disrupted genes. This can partly explain the different immune responses both serovars induce upon entering their host. Similar genome degradation is also observed in the ST313 S. Typhimurium strain implicated in invasive infection in sub-Saharan Africa. Virulence factors, most notably, type III secretion systems, Vi antigen, lipopolysaccharide and other surface polysaccharides, flagella, and various factors essential for the intracellular life cycle of S. enterica have been characterized. Genes for these factors are commonly carried on Salmonella Pathogenicity Islands (SPIs). Plasmids also carry putative virulence-associated genes as well as those responsible for antimicrobial resistance. The interaction of Salmonella pathogen-associated molecular patterns (PAMPs) with Toll-like receptors (TLRs) and NOD-like receptors (NLRs) leads to inflammasome formation, activation, and recruitment of neutrophils and macrophages and the production of pro-inflammatory cytokines, most notably interleukin (IL)-6, IL-1ß, tumor necrosis factor (TNF)-α, and interferon-gamma (IFN)-γ. The gut microbiome may be an important modulator of this immune response. S. Typhimurium usually causes a local intestinal immune response, whereas S. Typhi, by preventing neutrophil attraction resulting from activation of TLRs, evades the local response and causes systemic infection. Potential new therapeutic strategies may lead from an increased understanding of infection pathogenesis.

Monoclonal antibody applications in travel medicine.

For decades, immunoglobulin preparations have been used to prevent or treat infectious diseases. Since only a few years, monoclonal antibody applications (mAbs) are taking flight and are increasingly dominating this field. In 2014, only two mAbs were registered; end of October 2023, more than ten mAbs are registered or have been granted emergency use authorization, and many more are in (pre)clinical phases. Especially the COVID-19 pandemic has generated this surge in licensed monoclonal antibodies, although multiple phase 1 studies were already underway in 2019 for other infectious diseases such as malaria and yellow fever. Monoclonal antibodies could function as prophylaxis (i.e., for the prevention of malaria), or could be used to treat (tropical) infections (i.e., rabies, dengue fever, yellow fever). This review focuses on the discussion of the prospects of, and obstacles for, using mAbs in the prevention and treatment of (tropical) infectious diseases seen in the returning traveler; and provides an update on the mAbs currently being developed for infectious diseases, which could potentially be of interest for travelers.

Long-term immunity following yellow fever vaccination: a systematic review and meta-analysis.

BACKGROUND: Long-term immunity following yellow fever vaccination remains controversial. We aimed to summarise the literature regarding the long-term protection (≥10 years) conveyed by a single dose of yellow fever vaccination. METHODS: In this systematic review and meta-analysis, we searched 11 databases from database inception to Aug 24, 2023. We included cohort and cross-sectional studies reporting immunogenicity outcomes for children or adults who received a single dose of yellow fever vaccination 10 or more years ago. Case series and single case reports were excluded. Participants who received more than one dose of yellow fever vaccination before measurement of the outcome were excluded. Identified records were reviewed by two independent reviewers. The primary outcome of the meta-analysis was the pooled seroprotection rate. Risk of bias was assessed with the Risk Of Bias In Non-randomized Studies of Interventions tool, and the Joanna Briggs Institute tool for analytical cross-sectional studies. Studies of moderate or good quality that reported seroprotection were included for random-effects meta-analysis and stratified by endemicity and specific risk groups. The study was registered with PROSPERO, CRD42023384087. FINDINGS: Of the 7363 articles identified by our search, 39 were eligible for inclusion for systematic review. These studies comprised 2895 individuals vaccinated 10-60 years ago. 20 studies were included in the meta-analysis. Pooled seroprotection rates were 94% (95% CI 86-99) among healthy adults in a non-endemic setting (mostly travellers) and 76% (65-85) in an endemic setting (all Brazilian studies). The pooled seroprotection rate was 47% (35-60) in children (aged 9-23 months at time of vaccination) and 61% (38-82) in people living with HIV. Reported criteria for seroprotection were highly heterogeneous. INTERPRETATION: The gathered evidence suggests that a single dose of yellow fever vaccination provides lifelong protection in travellers. However, in people living with HIV and children (younger than 2 years), booster doses might still be required because lower proportions of vaccinees were seroprotected 10 or more years post-vaccination. Lower observed seroprotection rates among residents of endemic areas were partly explained by the use of a higher cutoff for seroprotection that was applied in Brazil. Studies from sub-Saharan Africa were scarce and of low quality; thus no conclusions could be drawn for this region. FUNDING: None.

Overcoming publication and dissemination bias in infectious diseases clinical trials.

Non-timely reporting, selective reporting, or non-reporting of clinical trial results are prevalent and serious issues. WHO mandates that summary results be available in registries within 12 months of study completion and published in full text within 24 months. However, only a limited number of clinical trials in infectious diseases, including those done during the COVID-19 pandemic, have their results posted on ClinicalTrials.gov. An analysis of 50 trials of eight antiviral drugs tested against COVID-19 with a completion date of at least 2 years ago revealed that only 18% had their results published in the registry, with 40% not publishing any results. Non-timely and non-reporting practices undermine patient participation and are ethically unacceptable. Strategies should include obligatory reporting of summary results within 12 months in clinical trial registries, with progress towards peer-reviewed publication within 24 months indicated. Timely publication of research papers should be encouraged through an automated flagging mechanism in clinical trial registries that draws attention to the status of results reporting, such as a green tick for trials that have reported summary results within 12 months and a red tick in case of failure to do so. We propose the inclusion of mandatory clinical trial reporting standards in the International Conference on Harmonization Good Clinical Practice guidelines, which should prohibit sponsor contract clauses that restrict reporting (referred to as gag clauses) and require timely reporting of results as part of the ethics committees' clearance process for clinical trial protocols.

On the potential for discontinuing atovaquone-proguanil (AP) ad-hoc post-exposure and other abbreviated AP-regimens: Pharmacology, pharmacokinetics and perspectives.

According to current guidelines, atovaquone-proguanil (AP) malaria chemoprophylaxis should be taken once daily starting one day before travel and continued for seven days post-exposure. However, drug-sparing regimens, including discontinuing AP after leaving malaria-endemic areas are cost-saving and probably more attractive to travelers, and may thus enhance adherence. AP has causal prophylactic effects, killing malaria parasites during the hepatic stage. If early hepatic stages were already targeted by AP, AP could possibly be discontinued upon return. Pharmacokinetic data and studies on drug-sparing AP regimens suggest this to be the case. Nevertheless, the evidence is weak and considered insufficient to modify current recommendations. Field trials require large numbers of travelers and inherently suffer from the lack of a control group. Safely-designed controlled human malaria infection trials could significantly reduce study participant numbers and safely establish an effective AP abbreviated regimen which we propose as the optimal trial design to test this concept.

Can haematological changes constitute a surrogate diagnostic parameter to detect schistosomiasis in migrants and travellers? - A retrospective analysis.

Background: Earlier studies found characteristic haematological changes in African patients with active schistosomiasis. If consistently present, full blood counts (FBC) may be helpful to diagnose schistosomiasis also in migrants and returning travellers. Methods: A retrospective patient record review was conducted on data from seven European travel clinics, comparing FBC of Schistosoma egg-positive travellers and migrants to reference values. Sub-analyses were performed for children, returned travellers, migrants and different Schistosoma species. Results: Data analysis included 382 subjects (median age 21.0 years [range 2-73]). In returned travellers, decreases in means of haemoglobin particularly in females (ß = -0.82 g/dL, p = 0.005), MCV (ß = -1.6 fL, p = 0.009), basophils, neutrophils, lymphocytes and monocytes (ß = -0.07, p < 0.001; -0.57, p = 0.012; -0.57, p < 0.001 and -0.13 103/µL, p < 0.001, respectively) were observed. As expected, eosinophils were increased (ß = +0.45 103/µL, p < 0.001). In migrants, a similar FBC profile was observed, yet thrombocytes and leukocytes were significantly lower in migrants (ß = -48 103/µL p < 0.001 and ß = -2.35 103/µL, p < 0.001, respectively). Conclusions: Active egg-producing Schistosoma infections are associated with haematological alterations in returned travellers and migrants. However, these differences are discrete and seem to vary among disease stage and Schistosoma species. Therefore, the FBC is unsuitable as a surrogate diagnostic parameter to detect schistosomiasis.

Discontinuing atovaquone/proguanil prophylaxis ad-hoc post-exposure and during-travel dose-sparing prophylactic regimens against P. falciparum malaria: An update with pointers for future research.

BACKGROUND: Atovaquone/proguanil (AP) is a highly effective malaria chemoprophylaxis combination. According to current guidelines, AP is taken once daily during, and continued for seven days post exposure. A systematic review by Savelkoel et al. summarised data up to 2017 on abbreviated AP regimens, and concluded that discontinuing AP upon return may be effective, although the available data was insufficient to modify current recommendations. The same applies to other studies evaluating during-travel dose-sparing regimens. METHODS: A literature search in Pubmed and Embase was performed including search terms related to AP prophylaxis and pharmacokinetics to search for recent studies on abbreviated AP regimens published since 2017. RESULTS: Since the 2017 review, no new studies assessing discontinuing AP ad-hoc post-exposure prophylaxis have been published. Two new studies were identified assessing other abbreviated AP regimens; one investigated a twice-weekly AP regimen in 32 travellers, and one a three-day AP course in therapeutic dose (1000/400 mg) prior to exposure in 215 travellers. No malaria cases were detected in the study participants adhering to these regimens. CONCLUSIONS: Further research would be needed if the research question is considered of sufficient importance to facilitate evidence-based decision-making to modify current guidelines, as efficacy studies in travellers are fraught with confounders. We recommend human challenge trials to study abbreviated AP regimens pertaining to malaria chemoprophylaxis as they allow for rational, subject number, time- and cost-saving trial designs.

Altered Patterns of Compositional and Functional Disruption of the Gut Microbiota in Typhoid Fever and Nontyphoidal Febrile Illness.

BACKGROUND: Experimental murine models and human challenge studies of Salmonella Typhi infection have suggested that the gut microbiome plays an important protective role against the development of typhoid fever. Anaerobic bacterial communities have been hypothesized to mediate colonization resistance against Salmonella species by producing short-chain fatty acids, yet the composition and function of the intestinal microbiota in human patients with typhoid fever remain ill defined. METHODS: We prospectively collected fecal samples from 60 febrile patients admitted to Chittagong Medical College Hospital, Bangladesh, with typhoid fever or nontyphoidal febrile illness and from 36 healthy age-matched controls. The collected fecal samples were subjected to 16s rRNA sequencing followed by targeted metabolomics analysis. RESULTS: Patients with typhoid fever displayed compositional and functional disruption of the gut microbiota compared with patients with nontyphoidal febrile illness and healthy controls. Specifically, typhoid fever patients had lower microbiota richness and alpha diversity and a higher prevalence of potentially pathogenic bacterial taxa. In addition, a lower abundance of short-chain fatty acid-producing taxa was seen in typhoid fever patients. The differences between typhoid fever and nontyphoidal febrile illness could not be explained by a loss of colonization resistance after antibiotic treatment, as antibiotic exposure in both groups was similar. CONCLUSIONS: his first report on the composition and function of the gut microbiota in patients with typhoid fever suggests that the restoration of these intestinal commensal microorganisms could be targeted using adjunctive, preventive, or therapeutic strategies.

An unexpected reduction in sucrose concentration activates the HPA axis on successive post shift days without attenuation by discriminative contextual stimuli.

Previous studies have shown that the successive negative contrast procedure, in which food-restricted rats entrained to once daily, brief presentations of 32% sucrose are unexpectedly shifted to a 4% solution, results in an adrenocortical response on the second, but not the first postshift day. We attempted to generalize that finding in our own procedure. In Experiment 1, two groups of rats were given a 32% sucrose solution once daily in their home cages for 14 days before being shifted to a 4% solution. One group was killed 10 min after the first 4% solution and one was killed after the second 4% solution. In addition, two groups receiving either 32% or 4% sucrose throughout the experiment served as unshifted controls. In contrast to previous findings, both shifted groups exhibited prominent adrenocorticotropin hormone (ACTH) and adrenocortical (B) responses on both postshift days compared to unshifted controls, which did not differ from one another. Experiment 2a employed distinctive contexts to test if the lack of generality of the delayed HPA axis response was due to suppressive effects of S(+) on the first postshift day. Rats were given once daily 32% sucrose in S(+) and equal exposure time in S(-). Half of these rats were shifted to 4% sucrose in S(+) and half were shifted in S(-). These two groups were compared to home cage controls. Half of each group was killed after their first 4% sucrose, and half after the second 4% sucrose. All rats showed ACTH and B responses comparable to shifted rats in Experiment 1. S(+) failed to suppress the HPA axis, and the stress response was higher on the first compared to the second day of the shift. Experiment 2b established that distinctive contexts predicting sucrose, S(+), or not predicting sucrose, S(-), controlled behavioral choice and contextual discrimination. Thus, there was no evidence that issues of stimulus control could explain the lack of generality of previous findings. The data indicate that thwarting sucrose expectancies is stressful, and that this stress response habituates across days.

A novel view on the pathogenesis of complications after intravesical BCG for bladder cancer.

Intravesical bacillus Calmette-Guérin (BCG) is widely used for high-risk, non-muscle-invasive bladder cancer. This report describes four cases that illustrate the spectrum of BCG-induced complications, varying from granulomatous prostatitis to sepsis. There is considerable debate regarding whether inflammation or infection is the predominant mechanism in the pathogenesis of BCG disease. In two patients with a systemic illness, the symptoms first resolved after adding prednisone, indicating a principal role for inflammation in systemic disease. In vitro testing of T-cell responses and a mycobacterial growth inhibition assay were performed for these patients with systemic disease. The patient with mild symptoms showed more effective in vitro growth reduction of BCG, while the patient with sepsis and organ involvement had high T-cell responses but ineffective killing. While these findings are preliminary, it is believed that immunological assays, as described in this report, may provide a better insight into the pathogenesis of BCG disease in individual patients, justifying further research.

Activation of coagulation and endothelium with concurrent impairment of anticoagulant mechanisms in patients with typhoid fever.

OBJECTIVES: Typhoid fever caused by Salmonella Typhi remains a major burden worldwide. Gastrointestinal bleeding can be seen in up to 10 percent of patients and may be fatal. The coagulopathy, which may be the driver of this severe complication in patients with typhoid fever, however is ill defined. The aim of this study was to evaluate the activation of coagulation, anticoagulation, and fibrinolysis in patients with acute typhoid fever. METHODS: Parameters of coagulation and fibrinolysis were measured in 28 hospitalized patients with culture-confirmed or PCR-confirmed typhoid fever and compared to 38 age- and sex-matched healthy volunteers. RESULTS: Patients demonstrated activation of the coagulation system, as reflected by elevated in vitro thrombin generation and high plasma levels of fibrinogen, D-dimer and prothrombin fragment F1 + 2 in concert with consumption of coagulation factors resulting in a prolonged prothrombin-time and activated-partial-thromboplastin-time. Concurrently, the anticoagulant proteins, protein C and antithrombin, were significantly lower in comparison to healthy controls. Patients also demonstrated evidence of activation and inhibition of fibrinolysis and a marked activation of endothelial cells. The extent of coagulation activation was associated with the course of the disease, repeated testing during convalescence showed a return toward normal values. CONCLUSIONS: Activation of coagulation is an important clinical feature of typhoid fever and is associated with severity of disease.