Erectile dysfunction: an early marker for hypertension? A longitudinal study in spontaneously hypertensive rats

Erectile dysfunction (ED) is another manifestation of vascular disease. We evaluated the natural history of ED in the spontaneously hypertensive rat (SHR) and the respective participation of associated pathophysiological modifications, i.e., endothelial dysfunction and tissue remodeling. SHR and their normotensive counterparts [Wistar-Kyoto rats (WKY)] of 6, 12, and 24 wk of age (n = 12) were used to evaluate erectile function, erectile and aortic tissue reactivity, and remodeling. Erectile responses in SHR are reduced at all ages (P < 0.001). In both aortic and erectile tissues of SHR and WKY, relaxations to ACh are altered progressively with age, although more markedly in SHR. They are decreased at 12 wk of age in erectile tissue of SHR compared with WKY (maximal relaxation: -19.2 +/- 2.8% vs. -28.3 +/- 3.9%, P < 0.001) but only at 24 wk of age in aortas (-47.9 +/- 6.4% vs. -90.5 +/- 2.9%, P < 0.001). Relaxations to sodium nitroprusside are unaltered in aortic rings of both strains but enhanced in erectile tissue of SHR at 12 wk of age. Major modifications in the distribution of collagen I, III, and V in SHR occur in both types of tissue and are detectable sooner in erectile tissue compared with aortic tissue. The onset of ED is detectable before the onset of hypertension in the SHR. Structural and functional alterations, while similar, occur earlier in erectile compared with vascular tissue. If confirmed in humans, ED could be an early warning sign for hypertension, and common therapeutic strategies targeting both ED and hypertension could be investigated.     

Genetic elucidation of human hyperosmia to isovaleric acid

The genetic basis of odorant-specific variations in human olfactory thresholds, and in particular of enhanced odorant sensitivity (hyperosmia), remains largely unknown. Olfactory receptor (OR) segregating pseudogenes, displaying both functional and nonfunctional alleles in humans, are excellent candidates to underlie these differences in olfactory sensitivity. To explore this hypothesis, we examined the association between olfactory detection threshold phenotypes of four odorants and segregating pseudogene genotypes of 43 ORs genome-wide. A strong association signal was observed between the single nucleotide polymorphism variants in OR11H7P and sensitivity to the odorant isovaleric acid. This association was largely due to the low frequency of homozygous pseudogenized genotype in individuals with specific hyperosmia to this odorant, implying a possible functional role of OR11H7P in isovaleric acid detection. This predicted receptor–ligand functional relationship was further verified using the Xenopus oocyte expression system, whereby the intact allele of OR11H7P exhibited a response to isovaleric acid. Notably, we also uncovered another mechanism affecting general olfactory acuity that manifested as a significant inter-odorant threshold concordance, resulting in an overrepresentation of individuals who were hyperosmic to several odorants. An involvement of polymorphisms in other downstream transduction genes is one possible explanation for this observation. Thus, human hyperosmia to isovaleric acid is a complex trait, contributed to by both receptor and other mechanisms in the olfactory signaling pathway.     

Application of expert networks for predicting proteins secondary structure

The present study utilizes expert neural networks for the prediction of proteins secondary structure. We use three independent networks, one for each structure (alpha, beta and coil) as the first-level processing unit; decision upon the chosen structure for each residue is carried out by a second-level, post-processing unit, which utilizes the Chou and Fasman frequency values Falpha and Fbeta in order to strengthen and/or deplete the probability of the specific structure under investigation. The highest prediction case was 76%. Our method requires primitive computational means and a relatively small training set, while still been comparable to previous work. It is not meant to be an alternative to the determination of secondary structure by means of free energy minimization, integration of dynamic equations of motion or crystallography, which are expensive, time-consuming and complicated, but to provide additional constrains, which might be considered and incorporated into larger computing setups in order to reduce the initial search space for the above methods.     

The cytokine midkine and its receptor RPTPζ regulate B cell survival in a pathway induced by CD74

Lasting B cell persistence depends on survival signals that are transduced by cell surface receptors. In this study, we describe a novel biological mechanism essential for survival and homeostasis of normal peripheral mature B cells and chronic lymphocytic leukemia cells, regulated by the heparin-binding cytokine, midkine (MK), and its proteoglycan receptor, the receptor-type tyrosine phosphatase ζ (RPTPζ). We demonstrate that MK initiates a signaling cascade leading to B cell survival by binding to RPTPζ. In mice lacking PTPRZ, the proportion and number of the mature B cell population are reduced. Our results emphasize a unique and critical function for MK signaling in the previously described MIF/CD74-induced survival pathway. Stimulation of CD74 with MIF leads to c-Met activation, resulting in elevation of MK expression in both normal mouse splenic B and chronic lymphocytic leukemia cells. Our results indicate that MK and RPTPζ are important regulators of the B cell repertoire. These findings could pave the way toward understanding the mechanisms shaping B cell survival and suggest novel therapeutic strategies based on the blockade of the MK/RPTPζ-dependent survival pathway.     

Cytosolic activity of SPINDLY implies the existence of a DELLA-independent gibberellin-response pathway

Specific plant developmental processes are modulated by cross-talk between gibberellin (GA)- and cytokinin-response pathways. Coordination of the two pathways involves the O-linked N -acetylglucosamine transferase SPINDLY (SPY) that suppresses GA signaling and promotes cytokinin responses in Arabidopsis. Although SPY is a nucleocytoplasmic protein, its site of action and targets are unknown. Several studies have suggested that SPY acts in the nucleus, where it modifies nuclear components such as the DELLA proteins to regulate signaling networks. Using chimeric GFP–SPY fused to a nuclear-export signal or to a glucocorticoid receptor, we show that cytosolic SPY promotes cytokinin responses and suppresses GA signaling. In contrast, nuclear-localized GFP–SPY failed to complement the spy mutation. To examine whether modulation of cytokinin activity by GA and spy is mediated by the nuclear DELLA proteins, cytokinin responses were studied in double and quadruple della mutants lacking the activities of REPRESSOR OF GA1-3 (RGA) and GA-INSENSITIVE (GAI) or RGA, GAI, RGA Like1 (RGL1) and RGL2. Unlike spy , the della mutants were cytokinin-sensitive. Moreover, when GA was applied to a cytokinin-treated quadruple della mutant it was able to suppress various cytokinin responses. These results suggest that cytosolic SPY and GA regulate cytokinin responses via a DELLA-independent pathway(s).     

Accelerated biodegradation of cement by sulfur-oxidizing bacteria as a bioassay for evaluating immobilization of low-level radioactive waste

Disposal of low-level radioactive waste by immobilization in cement is being evaluated worldwide. The stability of cement in the environment may be impaired by sulfur-oxidizing bacteria that corrode the cement by producing sulfuric acid. Since this process is so slow that it is not possible to perform studies of the degradation kinetics and to test cement mixtures with increased durability, procedures that accelerate the biodegradation are required. Semicontinuous cultures of Halothiobacillus neapolitanus and Thiomonas intermedia containing thiosulfate as the sole energy source were employed to accelerate the biodegradation of cement samples. This resulted in a weight loss of up to 16% after 39 days, compared with a weight loss of 0.8% in noninoculated controls. Scanning electron microscopy of the degraded cement samples revealed deep cracks, which could be associated with the formation of low-density corrosion products in the interior of the cement. Accelerated biodegradation was also evident from the leaching rates of Ca(2+) and Si(2+), the major constituents of the cement matrix, and Ca exhibited the highest rate (up to 20 times greater than the control rate) due to the reaction between free lime and the biogenic sulfuric acid. Leaching of Sr(2+) and Cs(+), which were added to the cement to simulate immobilization of the corresponding radioisotopes, was also monitored. In contrast to the linear leaching kinetics of calcium, silicon, and strontium, the leaching pattern of cesium produced a saturation curve similar to the control curve. Presumably, the leaching of cesium is governed by the diffusion process, whereas the leaching kinetics of the other three ions seems to governed by dissolution of the cement.     

Listeria monocytogenes Multidrug Resistance Transporters and Cyclic Di-AMP,Which Contribute to Type I Interferon Induction,Play a Role in Cell Wall Stress

The intracellular bacterial pathogen Listeria monocytogenes activates a robust type I interferon response upon infection. This response is partially dependent on the multidrug resistance (MDR) transporter MdrM and relies on cyclic-di-AMP (c-di-AMP) secretion, yet the functions of MdrM and cyclic-di-AMP that lead to this response are unknown. Here we report that it is not MdrM alone but a cohort of MDR transporters that together contribute to type I interferon induction during infection. In a search for a physiological function of these transporters, we revealed that they play a role in cell wall stress responses. A mutant with deletion of four transporter genes (ΔmdrMTAC) was found to be sensitive to sublethal concentrations of vancomycin due to an inability to produce and shed peptidoglycan under this stress. Remarkably, c-di-AMP is involved in this phenotype, as overexpression of the c-di-AMP phosphodiesterase (PdeA) resulted in increased susceptibility of the ΔmdrMTAC mutant to vancomycin, whereas overexpression of the c-di-AMP diadenylate cyclase (DacA) reduced susceptibility to this drug. These observations suggest a physiological association between c-di-AMP and the MDR transporters and support the model that MDR transporters mediate c-di-AMP secretion to regulate peptidoglycan synthesis in response to cell wall stress.     

CXCR1 as a novel target for directing reactive T cells toward melanoma: implications for adoptive cell transfer immunotherapy

Adoptive cell transfer therapy with reactive T cells is one of the most promising immunotherapeutic modalities for metastatic melanoma patients. Homing of the transferred T cells to all tumor sites in sufficient numbers is of great importance. Here, we seek to exploit endogenous chemotactic signals in order to manipulate and enhance the directional trafficking of transferred T cells toward melanoma. Chemokine profiling of 15 melanoma cultures shows that CXCL1 and CXCL8 are abundantly expressed and secreted from melanoma cultures. However, the complimentary analysis on 40 melanoma patient-derived tumor-infiltrating lymphocytes (TIL) proves that the corresponding chemokine receptors are either not expressed (CXCR2) or expressed at low levels (CXCR1). Using the in vitro transwell system, we demonstrate that TIL cells preferentially migrate toward melanoma and that endogenously expressing CXCR1 TIL cells are significantly enriched among the migrating lymphocytes. The role of the chemokines CXCL1 and CXCL8 is demonstrated by partial abrogation of this enrichment with anti-CXCL1 and anti-CXCL8 neutralizing antibodies. The role of the chemokine receptor CXCR1 is validated by the enhanced migration of CXCR1-engineered TIL cells toward melanoma or recombinant CXCL8. Cytotoxicity and IFNγ secretion activity are unaltered by CXCR1 expression profile. Taken together, these results mark CXCR1 as a candidate for genetic manipulations to enhance trafficking of adoptively transferred T cells. This approach is complimentary and potentially synergistic with other genetic strategies designed to enhance anti-tumor potency.