Cloning of a cDNA encoding a plasma membrane-associated, uronide binding phosphoprotein with physical properties similar to viral movement proteins.

Oligogalacturonides are structural and regulatory homopolymers from the extracellular pectic matrix of plants. In vitro micromolar concentrations of oligogalacturonates and polygalacturonates were shown previously to stimulate the phosphorylation of a small plasma membrane-associated protein in potato. Immunologically cross-reactive proteins were detected in plasma membrane-enriched fractions from all angiosperm subclasses in the Cronquist system. Polygalacturonate-enhanced phosphorylation of the protein was observed in four of the six dicotyledon subclasses but not in any of the five monocotyledon subclasses. A cDNA for the protein was cloned from potato. The deduced protein is extremely hydrophilic and has a proline-rich N terminus. The C-terminal half of the protein was predicted to be a coiled coil, suggesting that the protein interacts with other macromolecules. The recombinant protein was found to bind both simple and complex galacturonides. The behavior of the protein suggests several parallels with viral proteins involved in intercellular communication.

Molecular mechanisms of insulin exocytosis role of small monomeric GTP-ASES

SUMMARYInsulin secretion from pancreatic beta-cells is a fundamental condition for the maintenance of blood glucose levels. During the last decades, important components of the molecular machinery controlling hormone release have been characterized. My PhD thesis was dedicated to the study of new signaling pathways regulating insulin exocytosis and in particular to the role of small monomelic guanine triphosphatase or GTPases controlling the last events of hormone release.The first part of my thesis focused on Ras-like (Ral) RalA and RalB proteins. We investigated the mechanisms leading to activation of Ral proteins in pancreatic beta-cells and analyzed their impact on different steps of the insulin-secretory process. Our results have shown that RalA is the predominant isoform expressed in pancreatic islets and insulin-secreting cell lines. Silencing of this GTPase in INS-IE cells by RNA interference led to a decrease in secretagogue-induced hormone release. The activation of the GTPase, followed by FRET imaging, is triggered by increases in intracellular Ca and cAMP. Defective insulin release in cells lacking RalA is associated with a decrease in the secretory granules docked at the plasma membrane, detected by TIRF microscopy and with strong impairment in PLD1 activation in response to secretagogues. RalA was found to be activated by the exchange factor RalGDS, which regulates hormone secretion induced by secretagogues and the docking step of insulin-containing granules at the plasma membrane. In the second part of this work we have shown that a member of the Rab family, Rab37, is present on insulin-containing secretory granules of pancreatic beta-cells. In addition, our experiments have suggested that Rab37 is required to obtain an optimal insulin secretory response induced by secretogogues and is important for the docking step of insulin-containing granules at the plasma membrane.

Small airways function declines after allogeneic haematopoietic stem cell transplantation.

Bronchiolitis obliterans (BO) following allogeneic haematopoietic stem cell transplantation (HSCT) affects peripheral airways. Detection of BO is presently delayed by the low sensitivity of spirometry. We examined the relationship between peripheral airway function and time since HSCT, and compared it with spirometry and clinical indices in 33 clinically stable allogeneic HSCT recipients. The following measurements were performed: lung function, exhaled nitric oxide, forced oscillatory respiratory system resistance and reactance, acinar (S(acin)) and conductive airways ventilation heterogeneity and lung clearance index (LCI) measured by multiple breath nitrogen washout. 22 patients underwent repeat visits from which short-term changes were examined. Median time post HSCT was 12 months. Eight patients were clinically diagnosed as having BO. In multivariate analysis, time since HSCT was predicted by S(acin) and forced expiratory volume in 1 s % predicted. 20 patients had abnormal S(acin) with normal spirometry, whereas none had airflow obstruction with normal S(acin). S(acin) and LCI were the only measures to change significantly between two visits, with both worsening. Change in S(acin) was the only parameter to correlate with change in chronic graft-versus-host disease grade. In conclusion, peripheral airways ventilation heterogeneity worsens with time after HSCT. S(acin) may be more sensitive than spirometry in detecting BO at an early stage, which needs confirmation in a prospective study.

Post-detection analysis for grating-based ultra-small angle X-ray scattering.

Until recently, the hard X-ray, phase-sensitive imaging technique called grating interferometry was thought to provide information only in real space. However, by utilizing an alternative approach to data analysis we demonstrated that the angular resolved ultra-small angle X-ray scattering distribution can be retrieved from experimental data. Thus, reciprocal space information is accessible by grating interferometry in addition to real space. Naturally, the quality of the retrieved data strongly depends on the performance of the employed analysis procedure, which involves deconvolution of periodic and noisy data in this context. The aim of this article is to compare several deconvolution algorithms to retrieve the ultra-small angle X-ray scattering distribution in grating interferometry. We quantitatively compare the performance of three deconvolution procedures (i.e., Wiener, iterative Wiener and Lucy-Richardson) in case of realistically modeled, noisy and periodic input data. The simulations showed that the algorithm of Lucy-Richardson is the more reliable and more efficient as a function of the characteristics of the signals in the given context. The availability of a reliable data analysis procedure is essential for future developments in grating interferometry.

Intravenous thrombolysis in patients with stroke attributable to small artery occlusion.

BACKGROUND: Intravenous thrombolysis (IVT) for stroke seems to be beneficial independent of the underlying etiology. Recent observations raised concern that IVT might cause harm in patients with strokes attributable to small artery occlusion (SAO). OBJECTIVE: The safety of IVT in SAO-patients is addressed in this study. METHODS: We used the Swiss IVT databank to compare outcome and complications of IVT-treated SAO-patients with IVT-treated patients with other etiologies (non-SAO-patients). Main outcome and complication measures were independence (modified Rankin scale <or=2) at 3 months, intracranial hemorrhage (ICH), and recurrent ischaemic stroke. RESULTS: Sixty-five (6.2%) of 1048 IVT-treated patients had SAO. Amongst SAO-patients, 1.5% (1/65) patients died, compared to 11.2% (110/983) in the non-SAO-group (P = 0.014). SAO-patients reached independence more often than non-SAO-patients (75.4% versus 58.9%; OR 2.14 (95% CI 1.20-3.81; P = 0.001). This association became insignificant after adjustment for age, gender, and stroke severity (OR 1.41 95% CI 0.713-2.788; P = 0.32). Glucose level and (to some degree) stroke severity but not age predicted 3-month-independence in IVT-treated SAO-patients. ICHs (all/symptomatic) were similar in SAO- (12.3%/4.6%) and non-SAO-patients (13.4%/5.3%; P > 0.8). Fatal ICH occurred in 3.3% of the non-SAO-patients but none amongst SAO-patients. Ischaemic stroke within 3 months after IVT reoccurred in 1.5% of SAO-patients and in 2.3% of non-SAO-patients (P = 0.68). CONCLUSION: IVT-treated SAO-patients died less often and reached independence more often than IVT-treated non-SAO-patients. However, the variable 'SAO' was a dependent rather than an independent outcome predictor. The absence of an excess in ICH indicates that IVT seems not to be harmful in SAO-patients.

Small RNA as global regulator of carbon catabolite repression in Pseudomonas aeruginosa.

In the metabolically versatile bacterium Pseudomonas aeruginosa, the RNA-binding protein Crc is involved in catabolite repression of a range of degradative genes, such as amiE (encoding aliphatic amidase). We found that a CA-rich sequence (termed CA motif) in the amiE translation initiation region was important for Crc binding. The small RNA CrcZ (407 nt) containing 5 CA motifs was able to bind the Crc protein with high affinity and to remove it from amiE mRNA in vitro. Overexpression of crcZ relieved catabolite repression in vivo, whereas a crcZ mutation pleiotropically prevented the utilization of several carbon sources. The sigma factor RpoN and the CbrA/CbrB two-component system, which is known to maintain a healthy carbon-nitrogen balance, were necessary for crcZ expression. During growth on succinate, a preferred carbon source, CrcZ expression was low, resulting in catabolite repression of amiE and other genes under Crc control. By contrast, during growth on mannitol, a poor carbon source, elevated CrcZ levels correlated with relief of catabolite repression. During growth on glucose, an intermediate carbon source, CrcZ levels and amiE expression were intermediate between those observed in succinate and mannitol media. Thus, the CbrA-CbrB-CrcZ-Crc system allows the bacterium to adapt differentially to various carbon sources. This cascade also regulated the expression of the xylS (benR) gene, which encodes a transcriptional regulator involved in benzoate degradation, in an analogous way, confirming this cascade's global role.

Phenotypic switching in Pseudomonas brassicacearum involves GacS- and GacA-dependent Rsm small RNAs.

The plant-beneficial bacterium Pseudomonas brassicacearum forms phenotypic variants in vitro as well as in planta during root colonization under natural conditions. Transcriptome analysis of typical phenotypic variants using microarrays containing coding as well as noncoding DNA fragments showed differential expression of several genes relevant to secondary metabolism and of the small RNA (sRNA) genes rsmX, rsmY, and rsmZ. Naturally occurring mutations in the gacS-gacA system accounted for phenotypic switching, which was characterized by downregulation of antifungal secondary metabolites (2,4-diacetylphloroglucinol and cyanide), indoleacetate, exoenzymes (lipase and protease), and three different N-acyl-homoserine lactone molecules. Moreover, in addition to abrogating these biocontrol traits, gacS and gacA mutations resulted in reduced expression of the type VI secretion machinery, alginate biosynthesis, and biofilm formation. In a gacA mutant, the expression of rsmX was completely abolished, unlike that of rsmY and rsmZ. Overexpression of any of the three sRNAs in the gacA mutant overruled the pleiotropic changes and restored the wild-type phenotypes, suggesting functional redundancy of these sRNAs. In conclusion, our data show that phenotypic switching in P. brassicacearum results from mutations in the gacS-gacA system.

Two GacA-dependent small RNAs modulate the quorum-sensing response in Pseudomonas aeruginosa.

In Pseudomonas aeruginosa, the GacS/GacA two-component system positively controls the quorum-sensing machinery and the expression of extracellular products via two small regulatory RNAs, RsmY and RsmZ. An rsmY rsmZ double mutant and a gacA mutant were similarly impaired in the synthesis of the quorum-sensing signal N-butanoyl-homoserine lactone, the disulfide bond-forming enzyme DsbA, and the exoproducts hydrogen cyanide, pyocyanin, elastase, chitinase (ChiC), and chitin-binding protein (CbpD). Both mutants showed increased swarming ability, azurin release, and early biofilm development.

Adiposity in children born small for gestational age.

Epidemiological studies indicate that children born small for gestational age (SGA) have an increased risk of metabolic and cardiovascular disorders as adults. This suggests that foetal undernutrition leads to permanent metabolic alterations, which predispose to metabolic abnormalities upon exposure to environmental factors such as low physical activity and/or high-energy intake in later life (thrifty phenotype hypothesis). However, this relationship is not restricted to foetal undernutrition or intrauterine growth retardation, but is also found for children born premature, or for high birth weight children. Furthermore, early post-natal nutrition, and more specifically catch-up growth, appear to modulate cardiovascular risk as well. Intrauterine growth retardation can be induced in animal models by energy/protein restriction, or ligation of uterine arteries. In such models, altered glucose homeostasis, including low beta-cell mass, low insulin secretion and insulin resistance is observed after a few weeks of age. In humans, several studies have confirmed that children born SGA have insulin resistance as adolescents and young adults. Alterations of glucose homeostasis and increased lipid oxidation can indeed be observed already in non-diabetic children born SGA at early pubertal stages. These children also have alterations of stature and changes in body composition (increased fat mass), which may contribute to the pathogenesis of insulin resistance. Permanent metabolic changes induced by foetal/early neonatal nutrition (metabolic inprinting) may involve modulation of gene expression through DNA methylation, or alterations of organ structure. It is also possible that events occurring during foetal/neonatal development lead to long-lasting alterations of the hypothalamo-pituitary-adrenal axis or the hypothalamo-pituitary-insulin-like growth factor-1 axis.

Small dense lipoproteins, apolipoprotein B, and risk of coronary events in HIV-infected patients on antiretroviral therapy: the Swiss HIV Cohort Study.

OBJECTIVES: HIV infection and exposure to certain antiretroviral drugs is associated with dyslipidemia and increased risk for coronary events. Whether this risk is mediated by highly atherogenic lipoproteins is unclear. We investigated the association of highly atherogenic small dense low-density lipoproteins (LDLs) and apolipoprotein B and coronary events in HIV-infected individuals receiving antiretroviral therapy. METHODS: We conducted a case-control study nested into the Swiss HIV Cohort Study to investigate the association of small dense LDL and apolipoprotein B and coronary events in 98 antiretroviral drug-treated patients with a first coronary event (19 fatal and 79 nonfatal coronary events with 53 definite and 15 possible myocardial infarctions, 11 angioplasties or bypasses) and 393 treated controls matched for age, gender, and smoking status. Lipids were measured by ultracentrifugation. RESULTS: In models including cholesterol, triglycerides, high-density lipoprotein cholesterol, blood pressure, central obesity, diabetes, and family history, there was an independent association between small dense LDL and coronary events [odds ratio (OR) for 1 mg/dL increase: 1.06, 95% confidence interval (CI): 1.00 to 1.11] and apolipoprotein B (OR for 10 mg/dL increase: 1.16, 95% CI: 1.02 to 1.32). When adding HIV and antiretroviral therapy-related variables, ORs were 1.04 (95% CI: 0.99 to 1.10) for small dense LDL and 1.13 (95% CI: 0.99 to 1.30) for apolipoprotein B. In both models, blood pressure and HIV viral load was independently associated with the odds for coronary events. CONCLUSIONS: HIV-infected patients receiving antiretroviral therapy with elevate small dense LDL and apolipoprotein B are at increased risk for coronary events as are patients without sustained HIV suppression.

Production of Pseudomonas aeruginosa Intercellular Small Signaling Molecules in Human Burn Wounds

Pseudomonas aeruginosa has developed a complex cell-to-cell communication system that relies on low-molecular weight excreted molecules to control the production of its virulence factors. We previously characterized the transcriptional regulator MvfR, that controls a major network of acute virulence functions in P. aeruginosa through the control of its ligands, the 4-hydroxy-2-alkylquinolines (HAQs)-4-hydroxy-2-heptylquinoline (HHQ) and 3,4-dihydroxy-2-heptylquinoline (PQS). Though HHQ and PQS are produced in infected animals, their ratios differ from those in bacterial cultures. Because these molecules are critical for the potency of activation of acute virulence functions, here we investigated whether they are also produced during human P. aeruginosa acute wound infection and whether their ratio is similar to that observed in P. aeruginosa-infected mice. We found that a clinically relevant P. aeruginosa isolate produced detectable levels of HAQs with ratios of HHQ and PQS that were similar to those produced in burned and infected animals, and not resembling ratios in bacterial cultures. These molecules could be isolated from wound tissue as well as from drainage liquid. These results demonstrate for the first time that HAQs can be isolated and quantified from acute human wound infection sites and validate the relevance of previous studies conducted in mammalian models of infection.

Brain-derived neurotrophic factor-like immunoreactivity is localized mainly in small sensory neurons of rat dorsal root ganglia.

Brain-derived neurotrophic factor (BDNF) is a protein capable of supporting the survival and fiber outgrowth of peripheral sensory neurons. It has been argued that histological detection of BDNF has proven difficult because of its low molecular weight and relatively low expression. In the present study we report that rapid removal of dorsal root ganglia (DRG) from the rat, followed by rapid freezing and appropriate fixation with cold acetone, preserves BDNF in situ without altering protein antigenicity. Under these conditions, specific BDNF-like immunoreactivity was detected in DRG both in vivo and in vitro. During DRG development in vivo, BDNF-like immunoreactivity (BDNF-LI) was observed only in a subset of sensory neurons. BDNF-LI was confined to small neurons, after neurons became morphologically distinct on the basis of size. BDNF-L immunoprecipitate was detected only in neuronal cells, and not in satellite or Schwann cells. While in vivo BDNF localization was restricted to small neurons, practically all neurons in DRG cell culture displayed BDNF-LI. Small or large primary afferent neurons exhibited a faint but clear BDNF-LI during the whole life span of cultures. Again, non-neuronal cells were devoid of BDNF-LI. In conclusion, in DRG in vivo, specific BDNF-LI was confined to small B sensory neurons. In contrast, all DRG sensory neurons displayed BDNF-LI in vitro. The finding that BDNF expressed in all DRG neurons in vitro but not in vivo suggests that BDNF expression may be modulated by environmental factors.