Effects of inactivation-resistant agonists on the signalling,desensitization and down-regulation of bradykinin B2 receptors

Background and purpose:

A peptide bradykinin (BK) B₂ receptor agonist partially resistant to degradation, B-9972, down-regulates this receptor subtype. We have used another recently described non-peptide agonist, compound 47a, as a tool to study further the effects of metabolically more stable and thus persistent, agonists of the BK B₂ receptor on signalling, desensitization and down-regulation of this receptor.

Experimental approach and key results:

Compound 47a was a partial agonist at the B₂ receptor in the human umbilical vein, where it shared with B-9972 a very slow relaxation on washout, and in HEK 293 cell lines expressing tagged forms [myc, green fluorescent protein (GFP)] of the rabbit B₂ receptor. Compound 47a desensitized the umbilical vein to BK. In the cellular systems, the inactivation-resistant agonists induced [Ca²⁺]_i transients as brief as those of BK but affected other functions with a longer duration than BK [12 h; receptor endocytosis, endosomal β-arrestin_1/2 translocation, protein kinase C-dependent extracellular signal-regulated kinases (ERK)1/2 phosphorylation and c-Fos expression]. The B₂ receptor–GFP was degraded in cells exposed to B-9972 or compound 47a for 12 h. The non-peptide B₂ receptor antagonist LF 16-0687 prevented all effects of compound 47a, which were also absent in cells lacking recombinant B₂ receptors.

Conclusion and implications:

Inactivation-resistant agonists revealed a long-lasting assembly of the agonist–B₂ receptor–β-arrestin complexes in endosomal structures and induce ‘biased signalling’ (in terms of activation of ERK and c-Fos) as a function of time. Further, B-9972 and compound 47a, unlike BK, efficiently down-regulated BK B₂ receptors.     

Lexical diversity and productivity in French preschoolers: developmental, gender and sociocultural factors

In this study, we examined the influence of child gender and sociocultural (SCL) factors in language production. Subjects were French Parisian children in nine age groups (24, 27, 30, 33, 36, 39, 42, 45 and 48 months). A total of 316 language samples were recorded during a 20-min standardized play session. Measures of grammatical and lexical development included Mean Length of Utterance (MLU) and word type and token - specifically, grammatical words such as determiners, prepositions and pronouns as well as verbs. ANOVAs revealed strong influences of SCL, with children from high SCL families showing more complex lexical productions and a higher rate of development. These observations suggest that amount of exposure to language accounts for this differential rate of acquisition. Analyses also revealed a general effect of gender, showing a small advantage in language production for girls over boys until 36 months of age.     

Cervical Cancer in Sub-Saharan Africa: A Multinational Population-Based Cohort Study of Care and Guideline Adherence

BackgroundCervical cancer (CC) is the most common female cancer in many countries of sub‐Saharan Africa (SSA). We assessed treatment guideline adherence and its association with overall survival (OS).MethodsOur observational study covered nine population‐based cancer registries in eight countries: Benin, Ethiopia, Ivory Coast, Kenya, Mali, Mozambique, Uganda, and Zimbabwe. Random samples of 44–125 patients diagnosed from 2010 to 2016 were selected in each. Cancer‐directed therapy (CDT) was evaluated for degree of adherence to National Comprehensive Cancer Network (U.S.) Guidelines.ResultsOf 632 patients, 15.8% received CDT with curative potential: 5.2% guideline‐adherent, 2.4% with minor deviations, and 8.2% with major deviations. CDT was not documented or was without curative potential in 22%; 15.7% were diagnosed with International Federation of Gynecology and Obstetrics (FIGO) stage IV disease. Adherence was not assessed in 46.9% (no stage or follow‐up documented, 11.9%, or records not traced, 35.1%). The largest share of guideline‐adherent CDT was observed in Nairobi (49%) and the smallest in Maputo (4%). In patients with FIGO stage I–III disease (n = 190), minor and major guideline deviations were associated with impaired OS (hazard rate ratio [HRR], 1.73; 95% confidence interval [CI], 0.36–8.37; HRR, 1.97; CI, 0.59–6.56, respectively). CDT without curative potential (HRR, 3.88; CI, 1.19–12.71) and no CDT (HRR, 9.43; CI, 3.03–29.33) showed substantially worse survival.ConclusionWe found that only one in six patients with cervical cancer in SSA received CDT with curative potential. At least one‐fifth and possibly up to two‐thirds of women never accessed CDT, despite curable disease, resulting in impaired OS. Investments into more radiotherapy, chemotherapy, and surgical training could change the fatal outcomes of many patients.Implications for PracticeDespite evidence‐based interventions including guideline‐adherent treatment for cervical cancer (CC), there is huge disparity in survival across the globe. This comprehensive multinational population‐based registry study aimed to assess the status quo of presentation, treatment guideline adherence, and survival in eight countries. Patients across sub‐Saharan Africa present in late stages, and treatment guideline adherence is remarkably low. Both factors were associated with unfavorable survival. This report warns about the inability of most women with cervical cancer in sub‐Saharan Africa to access timely and high‐quality diagnostic and treatment services, serving as guidance to institutions and policy makers. With regard to clinical practice, there might be cancer‐directed treatment options that, although not fully guideline adherent, have relevant survival benefit. Others should perhaps not be chosen even under resource‐constrained circumstances.     

Acquired resistance to echinocandins in Candida albicans: case report and review

OBJECTIVES: A patient with Candida albicans thrush and oesophagitis was treated with high doses of caspofungin but treatment eventually failed. Four C. albicans isolates were serially recovered before and after caspofungin treatment. A microbiological study was performed to characterize these four isolates. METHODS: In vitro antifungal susceptibility testing was performed by the EUCAST reference method in RPMI and AM3 and by Etest. Molecular typing of the four isolates was done by sizing three polymorphic microsatellite markers. To look for specific mutations, sequencing of a region of the gene encoding the 1-3-beta-D-glucan synthase was performed for the four isolates. RESULTS: In vitro antifungal susceptibility testing showed an increase in both caspofungin and micafungin MICs for the two isolates recovered after caspofungin treatment failure. The best discrimination between the pre-treatment and post-treatment isolates was obtained with Etest. Molecular typing of the four isolates showed that the post-treatment isolates with reduced susceptibility were identical to a susceptible pre-treatment isolate, suggesting the acquisition of caspofungin resistance. Sequencing of the gene encoding the 1-3-beta-D-glucan synthase showed a mutation responsible for an amino acid change at Phe-641 that could confer reduced susceptibility to both echinocandins. CONCLUSIONS: Our results indicate that is it useful to perform in vitro susceptibility testing in the cases of clinical failure during caspofungin therapy.     

Combined chemotherapy including high-dose methotrexate in KSHV/HHV8-associated primary effusion lymphoma

Primary effusion lymphoma (PEL) is a rare KSHV/HHV8-associated high-grade non-Hodgkin's lymphoma (NHL) of B-cell origin, characterized by serous effusions in body cavities. Most patients are HIV-infected homosexual men with severe immunosuppression and other KSHV/HHV8-associated diseases such as Kaposi's sarcoma (KS). The prognosis is poor with a median survival of less than 6 months in most cohorts. The achievement of a sustained complete remission is rare. High-dose chemotherapy regimens are warranted to improve complete remission rate and survival. Seven patients with AIDS-associated PEL were treated with a combined chemotherapy including high-dose methotrexate followed by leucovorin rescue. In all cases, KSHV/HHV8 sequences were detected in the effusion samples using quantitative PCR assays. Five patients had a pre-existing KS, associated in three cases with multicentric Castleman's disease (MCD). Upon diagnosis, 6 patients received antiretroviral therapy, which was maintained during chemotherapy in 5 of them. At time of analysis, 3 out of 7 patients were in complete remission 18, 26, and 78 months after PEL diagnosis. Three patients died with a progressive PEL at 22, 67, and 153 days after diagnosis, and 1 patient died 9 months after PEL diagnosis with a MCD-associated plasmablastic NHL. Complete remission was obtained in 3 out of 7 patients treated for AIDS-associated PEL with combined chemotherapy containing high-dose methotrexate.     

Moth chemosensory protein exhibits drastic conformational changes and cooperativity on ligand binding

Chemosensory proteins (CSPs) have been proposed to transport hydrophobic chemicals from air to olfactory or taste receptors. They have been isolated from several sensory organs of a wide range of insect species. The x-ray structure of CSPMbraA6, a 112-aa antennal protein from the moth Mamestra brassicae (Mbra), was shown to exhibit a novel type of alpha-helical fold. We have performed a structural and binding study of CSPMbraA6 to get some insights into its possible molecular function. Tryptophan fluorescence quenching demonstrates the ability of CSPMbraA6 to bind several types of semio-chemicals or surrogate ligands with microM K(d). Its crystal structure in complex with one of these compounds, 12-bromo-dodecanol, reveals extensive conformational changes on binding, resulting in the formation of a large cavity filled by three ligand molecules. Furthermore, binding cooperativity was demonstrated for some ligands, suggesting a stepwise binding. The peculiar rearrangement of CSPMbraA6 conformation and the cooperativity phenomenon might trigger the recognition of chemicals by receptors and induce subsequent signal transduction.