A qualitative evaluation of the published oligonucleotides specific for the 16S rRNA gene sequences of the ammonia-oxidizing bacteria

Over the past few years, there has been an increasing interest in making oligonucleotides specific for ammonia-oxidizing bacteria (AOB), in order to detect and monitor these slow growing bacteria in environmental samples, in enrichment cultures and in wastewater treatment plants. Based on 16S rDNA sequences, a broad selection of oligonucleotides have been designed, either encompassing all known AOB in the beta-subgroup of the Proteobacteria (beta AOB), or subclasses within beta AOB. Thirty different oligonucleotides have so far been published, with varying specificity. The first AOB-specific oligonucleotides published were obtained as a result of an alignment of only eleven 16S rDNA sequences from AOB. Including the present study, there are now forty nearly full length 16S rDNA sequences available from these bacteria, in addition to a number of partial sequences, so that an improved evaluation of the published oligonucleotides can be done. Two new 16S rRNA gene sequences from Nitrosospira are presented here, in a phylogenetic analysis containing every 16S rRNA gene sequences (> 1 kb) available from AOB. On the basis of an alignment of all these sequences, combined with searches in the nucleotide sequence databases, an evaluation of the thirty published oligonucleotides is presented. The analysis expose the strength and weakness of each oligonucleotide and discuss the use of oligonucleotides specific for 16S rRNA genes in future studies of AOB. The present work also identifies one new, broad range primer, specific for the AOB in the beta-subgroup of the Proteobacteria.     

Von Willebrand disease: characteristics and response to desmopressin. Study of 103 cases

BACKGROUND: To describe the main characteristics and response to desmopressin infusion in 103 patients suffering from von Willebrand disease (vWD). PATIENTS AND METHODS: The criteria for diagnosis were (except for type 2N) the coexistence of von Willebrand factor ristocetin cofactor (vWF:RCo) activity < 50 U/dl with bleeding disease or one of the following data: von Willebrand factor antigen (vWF:Ag) activity < 50 U/dl, factor VIII (FVIII) activity < 50 U/dl or the existence of a increased bleeding time (BT). Multimeric studies of vWF were performed in 51 cases and ristocetin induced platelet aggregation (RIPA) was also performed. RESULTS: Spontaneous bleeding was found in 36 patients, while in 18 cases the diagnosis was done after surgical bleeding. Thirteen patients (6 presenting with mild bleeding) were studied for abnormalities in the routine preanestesic tests. Other 22 patients were diagnosed with vWD by familial studies. There were 3 patients with type 2B, 1 case with type 2N and other patient with type 3. BT was found increased in 26 out of 58 patients. The activities of vWF:CoR and vWF:Ag were 38.4 (9.4) U/dl and 45.8 (23.2) U/dl, respectively, while the activity of FVIII was 49.9 (20.8) U/dl. Prophylactic DDAVP (desmopressin) was infused in 32 patients. After 1 h, basal activities of vWF:CoR and vWF:Ag were increased by 3.1 (3.2) and 3.4 (3.1) times, respectively, and maintained for 3 h. FVIII activity increased 3.6 (2.3) times the basal levels decreasing after 3 h (2.9 [2.1]; p < 0.01). The BT was corrected in 8 out of ten patients. CONCLUSIONS: vWD is a major cause of surgical bleeding. Preanestesic anamnesis and coagulation tests can be useful to identify vWD. Many patients with vWD have normal BT. A failure in the response to desmopressin infusion is unusual.     

Histopathology of coronary lesions with early loss of minimal luminal diameter after successful percutaneous transluminal coronary angioplasty: is thrombus a significant contributor?

BACKGROUND: Early loss of minimal luminal diameter of >0.3 mm after successful percutaneous transluminal coronary angioplasty (PTCA) is associated with a higher incidence of restenosis. The underlying mechanism of this early loss is unknown and thrombus may be a contributing factor. METHODS: We performed a prospective study using quantitative computerized planimetry on coronary tissue specimens obtained by directional coronary atherectomy of 24 lesions in which early loss occurred 22+/-9 minutes after successful PTCA. RESULTS: Thrombus was present in 9 (37%) of 24 coronary specimens. Segmental areas (mm2) and percentage of total area were distributed as follows: sclerotic tissue, 4.07+/-0.7 mm2 (63%+/-6%); fibrocellular tissue, 0.97+/-0.27 mm2 (16%+/-4%); hypercellular tissue, 0.99+/-0.29 mm2 (12%+/-3%); atheromatous gruel, 0.18+/-0.07 mm2 (3%+/-0.1%); and thrombus, 0.24+/-0.15 mm2 (6%+/-0.4%). There was no difference in the relative early loss index between lesions with or without thrombus (35%+/-7% vs 26%+/-2%, respectively; P= .87). Multiple stepwise regression analysis did not identify any histologic predictors of relative early loss index. CONCLUSION: Histopathologic analysis of coronary lesions with early loss after successful PTCA suggests that thrombus may not play a significant role in this angiographic phenomenon.     

Temporal relationship between progestin and luteinizing hormone concentrations in pseudopregnant rats treated with prostaglandin-F2 alpha

The temporal changes in progesterone (delta 4P), 20 alpha-dihydroprogesterone (20 alpha-DHP) and luteinizing hormone (LH) concentrations in pseudopregnant (PSP) rats after treatment with a single subcutaneous Silastic-PVP tube containing 600 micrograms PGF2 alpha were correlated. Progesterone levels fell and LH levels rose significantly 2h after initiation of treatment, while 20 alpha-DHP levels were found to increase significantly 12h after treatment. Since the changes in delta 4P and LH concentrations occurred concurrently, it seems that the increase in LH levels could have been due to a direct effect of PGF2 alpha on the ovary causing a reduction in delta 4P and thus a negative feedback effect on LH release. Alternatively, PGF2 alpha might exert a direct effect on LH secretion at the hypothalamic-pituitary level.     

Hybridizing the cross-entropy method: An application to the max-cut problem

Cross-entropy has been recently proposed as a heuristic method for solving combinatorial optimization problems. We briefly review this methodology and then suggest a hybrid version with the goal of improving its performance. In the context of the well-known max-cut problem, we compare an implementation of the original cross-entropy method with our proposed version. The suggested changes are not particular to the max-cut problem and could be considered for future applications to other combinatorial optimization problems.     

Heterotrimeric G proteins physically associated with the lipopolysaccharide receptor CD14 modulate both in vivo and in vitro responses to lipopolysaccharide

Septic shock induced by lipopolysaccharide (LPS) triggering of cytokine production from monocytes/macrophages is a major cause of morbidity and mortality. The major monocyte/macrophage LPS receptor is the glycosylphosphatidylinositol (GPI)-anchored glycoprotein CD14. Here we demonstrate that CD14 coimmunoprecipitates with Gi/Go heterotrimeric G proteins. Furthermore, we demonstrate that heterotrimeric G proteins specifically regulate CD14-mediated, LPS-induced mitogen-activated protein kinase (MAPK) activation and cytokine production in normal human monocytes and cultured cells. We report here that a G protein binding peptide protects rats from LPS-induced mortality, suggesting a functional linkage between a GPI-anchored receptor and the intracellular signaling molecules with which it is physically associated.     

Hypoxia impairs vasodilation in the lung

Alveolar hypoxia causes pulmonary vasoconstriction; we investigated whether hypoxia could also impair pulmonary vasodilation. We found in the isolated perfused rat lung a delay in vasodilation following agonist-induced vasoconstriction. The delay was not due to erythrocyte or plasma factors, or to alterations in base-line lung perfusion pressure. Pretreating lungs with arachidonic acid abolished hypoxic vasoconstriction, but did not influence the hypoxia-induced impairment of vasodilation after angiotensin II, bradykinin, or serotonin pressor responses. Progressive slowing of vasodilation followed angiotensin II-induced constriction as the lung oxygen tension fell progressively below 60 Torr. KCl, which is not metabolized by the lung, caused vasoconstriction; the subsequent vasodilation time was delayed during hypoxia. However, catecholamine depletion in the lungs abolished this hypoxic vasodilation delay after KCl-induced vasoconstriction. In lungs from high altitude rats, the hypoxia-induced vasodilation impairment after an angiotensin II pressor response was markedly less than it was in lungs from low altitude rats. We conclude from these studies that (a) hypoxia impairs vasodilation of rat lung vessels following constriction induced by angiotensin II, serotonin, bradykinin, or KCl, (b) hypoxia slows vasodilation following KCl-induced vasoconstriction probably by altering lung handling of norepinephrine, (c) the effect of hypoxia on vasodilation is not dependent on its constricting effect on lung vessels, (d) high altitude acclimation moderates the effect of acute hypoxia on vasodilation, and (e) the hypoxic impairment of vasodilation is possibly the result of an altered rate of dissociation of agonists from their membrane receptors on the vascular smooth muscle.     

Increasing the Complexity of Magnetic Core/Shell Structured Nanocomposites for Biological Applications

This Review article ponders core/shell structured nanoparticles that can be prepared with features that combine properties of different materials, including ligands that enhance their biocompatibility. These nanocomposites are not classified in terms of synthesis, but rather by how these features are distributed in the final morphology, attending to connected or isolated materials that end up in interacting or not‐interacting functionalities. In particular, we have focused on magnetic core/shell‐structured particles with a directly connected, coupled, or isolated second functionality. The current progress on methods in colloidal solution that have allowed the great development of these multifunctional magnetic and active spheres on biological and biomedical fields is reported.