[Trend analysis of suicide among children, adolescent and young adults in Ecuador between 1990 and 2017]. / Análisis de tendencias temporales del suicidio en niños, adolescentes y adultos jóvenes en Ecuador entre 1990 y 2017.

BACKGROUND: Analyze the long-term sex specific trends in suicide rates for Ecuadorian children, adolescents and young people, as well as to describe the evolution of the male/female ratio between 1990 and 2017. METHOD: Population and mortality data were obtained from the National Institute of Statistics and Censuses of Ecuador. Suicide rates were calculated for each year, age group (10-14, 15-19, 20-24 years) and sex. We used the Joinpoint Regression Program 4.6.0.2 to analyze temporal trends and report annual percent change (APC) by each age group and sex. RESULTS: An average of 313 suicides per year happened in Ecuador between 1990 and 2017, with increases of 480% in young boys and 322 % in girls aged between 10-14, 111% in male adolescents and 57% in young adults, while there was a decrease in adolescent girls (19%) and young adults (37%). The suicide rate increased annually among boys (APC = 5.10%) and girls (2.57%), as well as for male adolescents (3.07%) and young adults (10.42%), while for female adolescents (0.81%, not significant) and young women (1.16%) the trend decreased after reaching a peak around 2006. While up until the beginning of the XXI century young females aged between 10 and 19 years had higher suicide rates, during the last decade men had higher rates across all age groups (between 1.5:1 and 4.3:1 in 2017). CONCLUSIONS: Suicide in the population under 25 years in Ecuador is a major public health issue and increased between 1990 and 2017, particularly among children, and males between 15-24 years. The intersectorial strategy proposed in 2018 in order to reduce suicide is pending further evaluation and interpretation.

Recognition of 16S rRNA by ribosomal protein S4 from Bacillus stearothermophilus.

Protein S4 is essential for bacterial small ribosomal subunit assembly and recognizes the 5' domain (approximately 500 nt) of small subunit rRNA. This study characterizes the thermodynamics of forming the S4-5' domain rRNA complex from a thermophile, Bacillus stearothermophilus, and points out unexpected differences from the homologous Escherichia coli complex. Upon incubation of the protein and RNA at temperatures between 35 and 50 degrees C under ribosome reconstitution conditions [350 mM KCl, 8 mM MgCl2, and 30 mM Tris (pH 7.5)], a complex with an association constant of > or = 10(9) M(-1) was observed, more than an order of magnitude tighter than previously found for the homologous E. coli complex under similar conditions. This high-affinity complex was shown to be stoichiometric, in equilibrium, and formed at rates on the order of magnitude expected for diffusion-controlled reactions ( approximately 10(7) M(-1) x s(-1)), though at low temperatures the complex became kinetically trapped. Heterologous binding experiments with E. coli S4 and 5' domain RNA suggest that it is the B. stearothermophilus S4, not the rRNA, that is activated by higher temperatures; the E. coli S4 is able to bind 5' domain rRNA equally well at 0 and 37 degrees C. Tight complex formation requires a low Mg ion concentration (1-2 mM) and is very sensitive to KCl concentration [- partial differential[log(K)]/partial differential(log[KCl]) = 9.3]. The protein has an unusually strong nonspecific binding affinity of 3-5 x 10(6) M(-1), detected as a binding of one or two additional proteins to the target 5' domain RNA or two to three proteins binding a noncognate 23S rRNA fragment of the approximately same size. This binding is not as sensitive to monovalent ion concentration [- partial differential[log(K)]/partial differential(log[KCl]) = 6.3] as specific binding and does not require Mg ion. These findings are consistent with S4 stabilizing a compact form of the rRNA 5' domain.

Structural preordering in the N-terminal region of ribosomal protein S4 revealed by heteronuclear NMR spectroscopy.

Protein S4, a component of the 30S subunit of the prokaryotic ribosome, is one of the first proteins to interact with rRNA in the process of ribosome assembly and is known to be involved in the regulation of this process. While the structure of the C-terminal 158 residues of Bacillus stearothermophilus S4 has been solved by both X-ray crystallography and NMR, that of the N-terminal 41 residues is unknown. Evidence suggests that the N-terminus is necessary both for the assembly of functional ribosomes and for full binding to 16S RNA, and so we present NMR data collected on the full-length protein (200 aa). Our data indicate that the addition of the N-terminal residues does not significantly change the structure of the C-terminal 158 residues. The data further indicate that the N-terminus is highly flexible in solution, without discernible secondary structure. Nevertheless, structure calculations based on nuclear Overhauser effect spectroscopic data combined with (15)N relaxation data revealed that two short segments in the N-terminus, S(12)RRL(15) and P(30)YPP(33), adopt transiently ordered states in solution. The major conformation of S(12)RRL(15) appears to orient the arginine side chains outward toward the solvent in a parallel fashion, while that of P(30)YPP(33) forms a nascent turn of a polyproline II helix. These segments contain residues that are highly conserved across many prokaryotic species, and thus they are reasonable candidates respectively for sites of interaction with RNA and other ribosomal proteins within the intact ribosome.

Refining the overall structure and subdomain orientation of ribosomal protein S4 delta41 with dipolar couplings measured by NMR in uniaxial liquid crystalline phases.

Prokaryotic protein S4 initiates assembly of the small ribosomal subunit by binding to 16 S rRNA. Residues 43-200 of S4 from Bacillus stearothermophilus (S4 Delta41) bind to both 16 S rRNA and to a mRNA pseudoknot. In order to obtain structure-based insights regarding RNA binding, we previously determined the solution structure of S4 Delta41 using NOE, hydrogen bond, and torsion angle restraints. S4 Delta41 is elongated, with two distinct subdomains, one all helical, the other including a beta-sheet. In contrast to the high resolution structures obtained for each individual subdomain, their relative orientation was not precisely defined because only 17 intersubdomain NOE restraints were determined. Compared to the 1.7 A crystal structure, when the sheet-containing subdomains are superimposed, the helical subdomain is twisted by almost 45 degrees about the long axis of the molecule in the solution structure. Because variations in subdomain orientation may explain how the protein recognizes multiple RNA targets, our current goal is to determine the orientation of the subdomains in solution with high precision. To this end, NOE assignments were re-examined. NOESY experiments on a specifically labeled sample revealed that one of the intersubdomain restraints had been misassigned. However, the revised set of NOE restraints produces solution structures that still have imprecisely defined subdomain orientations and that lie between the original NMR structure and the crystal structure. In contrast, augmenting the NOE restraints with N-H dipolar couplings, measured in uniaxial liquid crystalline phases, clearly establishes the relative orientation of the subdomains. Data obtained from two independent liquid crystalline milieux, DMPC/DHPC bicelles and the filamentous bacteriophage Pf1, show that the relative orientation of the subdomains in solution is quite similar to the subdomain orientation in the crystal structure. The solution structure, refined with dipolar data, is presented and its implications for S4's RNA binding activity are discussed.

The solution structure of ribosomal protein S4 delta41 reveals two subdomains and a positively charged surface that may interact with RNA.

S4 is one of the first proteins to bind to 16S RNA during assembly of the prokaryotic ribosome. Residues 43-200 of S4 from Bacillus stearothermophilus (S4 Delta41) bind specifically to both 16S rRNA and to a pseudoknot within the alpha operon mRNA. As a first step toward understanding how S4 recognizes and organizes RNA, we have solved the structure of S4 Delta41 in solution by multidimensional heteronuclear nuclear magnetic resonance spectroscopy. The fold consists of two globular subdomains, one comprised of four helices and the other comprised of a five-stranded antiparallel beta-sheet and three helices. Although cross-linking studies suggest that residues between helices alpha2 and alpha3 are close to RNA, the concentration of positive charge along the crevice between the two subdomains suggests that this could be an RNA-binding site. In contrast to the L11 RNA-binding domain studied previously, S4 Delta41 shows no fast local motions, suggesting that it has less capacity for refolding to fit RNA. The independently determined crystal structure of S4 Delta41 shows similar features, although there is small rotation of the subdomains compared with the solution structure. The relative orientation of the subdomains in solution will be verified with further study.

The crystal structure of ribosomal protein S4 reveals a two-domain molecule with an extensive RNA-binding surface: one domain shows structural homology to the ETS DNA-binding motif.

We report the 1.7 A crystal structure of ribosomal protein S4 from Bacillus stearothermophilus. To facilitate the crystallization, 41 apparently flexible residues at the N-terminus of the protein have been deleted (S4Delta41). S4Delta41 has two domains; domain 1 is completely alpha-helical and domain 2 comprises a five-stranded antiparallel beta-sheet with three alpha-helices packed on one side. Domain 2 is an insertion within domain 1, and it shows significant structural homology to the ETS domain of eukaryotic transcription factors. A phylogenetic analysis of the S4 primary structure shows that the likely RNA interaction surface is predominantly on one side of the protein. The surface is extensive and highly positively charged, and is centered on a distinctive canyon at the domain interface. The latter feature contains two arginines that are totally conserved in all known species of S4 including eukaryotes, and are probably crucial in binding RNA. As has been shown for other ribosomal proteins, mutations within S4 that affect ribosome function appear to disrupt the RNA-binding sites. The structure provides a framework with which to probe the RNA-binding properties of S4 by site-directed mutagenesis.

Effects of Mg2+, K+, and H+ on an equilibrium between alternative conformations of an RNA pseudoknot.

A complex pseudoknot structure surrounds the first ribosome initiation site in the Escherichia coli alpha mRNA and mediates its regulation by ribosomal protein S4. A 112 nt RNA fragment containing this pseudoknot exists in two conformations that are resolvable by gel electrophoresis below room temperature. Between 30 degrees C and 45 degrees C the conformers reach thermodynamic equilibrium on a time scale ranging from one hour to one minute, and the interconversion between conformers is linked to H+, K+ and Mg2+ concentrations. Mg2+ favors formation of the "fast" electrophoretic form: a single Mg2+ is bound in the rate-limiting step, followed by cooperative binding of approximately 1.7 additional ions. Binding of the latter ions provides most of the favorable free energy for the reaction. However, the "slow" form binds about the same number of Mg ions, albeit more weakly, so that saturating Mg2+ concentrations drive the equilibrium to only approximatley 70% fast form. A single H+ is taken up in the switch to the "slow" conformer, which has apparent pK approximately 5.9; low pH also stabilizes part of the pseudoknot structure melting at approximately 62 degrees C. Mg2+ and H+ appear to direct alpha mRNA folding by relatively small (10 to 100-fold) differences in their affinities for alternative conformers. K+ has very little effect on the conformational equilibrium, but at high concentrations accelerates interconversion between the conformers. The alpha mRNA conformational switch is similar in its slow kinetics, large activation energy, and Mg2+ dependence of the equilibrium constant to slow steps in the folding of tRNA, group I introns, and RNase P RNA tertiary structures, though it differs from these in the association of a single Mg2+ with the rate-limiting step.

A conformational switch in a regulated mRNA involves tertiary structure.

The E. coli alpha operon mRNA is autogenously regulated by binding the repressor ribosomal protein S4. Repression occurs via a novel mechanism in which S4 traps the mRNA in a conformation that prevents formation of the complete initiation complex. The conformations have similar stabilities but separated by a high activation energy which is a criterion for a conformational switch. The conformation switch is likely to involve alteration in tertiary structure as indicated by gel electrophoresis and thermal denaturation experiments. It was found that Mg2+ stabilizes the repressed form and tertiary structure, and H+ stabilizes the translated form and have complicated effects on tertiary structure.

[Doppler sonographic detection of reduced flow velocity in the celiac trunk of the newborn infant with patent ductus arteriosus Botalli compared to a healthy control group]. / Dopplersonographischer Nachweis erniedrigter Flussgeschwindigkeiten im Truncus Coeliacus beim offenen Ductus Arteriosus Botalli des Frühgeborenen im Vergleich zu einer gesunden Kontrollgruppe.

Pulsed doppler recordings were obtained in the truncus coeliacus in 12 premature born infants (gestational age 30.3 +/- 2.5 weeks) with the clinical signs of patent ductus arteriosus Botalli (PDA) and compared to a control group of 24 healthy infants (gestational age 40.5 +/- 5.3 weeks). In all children the maximal systolic velocity, the endsystolic and the enddiastolic velocity and the pulsatility-index were measured. The 24 healthy newborns showed the following velocities: Maximal systolic velocity: 77 +/- 16 cm X s-1; endsystolic velocity: 31 +/- 10 cm X s-1; enddiastolic velocity; 18 +/- 9 cm X s-1. The pulsatility-index was 0.75 +/- 0.11. In children with PDA the maximal systolic velocity was 72 +/- 21 cm X s-1, the endsystolic velocity 15 +/- 14 cm X s-1 and the enddiastolic velocity -5 +/- 8 cm X s-1. The pulsatility-index was 1.08 +/- 0.12. All infants with large PDA showed a significant decrease of the endsystolic velocity and enddiastolic velocity, whereas the pulsatility-index was significantly increased. The decrease of the endsystolic and enddiastolic velocity in infants with large PDA in comparison to the healthy control group may lead to hypoxemic-ischemic lesions of the intestinal organs. The increased incidence of necrotizing enterocolitis in premature infants with large PDA may be the result of hypoperfusion of the small bowel.

[Doppler sonographic flow parameter of the anterior cerebral artery in patent ductus arteriosus of the newborn infant compared to a healthy control sample]. / Dopplersonographische Flussparameter in der Arteria cerebri anterior beim offenen Ductus arteriosus des Frühgeborenen im Vergleich zu einem gesunden Kontrollkollektiv.

33 premature infants (age: 32 +/- 3 weeks; birth weight 1,268 +/- 535 gs) with the clinical signs of patent ductus arteriosus Botalli (PDA) and a control group of 96 healthy infants (age: 37 +/- 4 weeks; birth weight 2 348 +/- 944 gs) were investigated. Pulsed doppler recordings were obtained in the anterior cerebral arteries (ACA) and compared with the flow pattern in the truncus coeliacus (TC). In all children the maximal systolic velocity (Vs), the endsystolic (Ves) and the enddiastolic velocity (Ved) and the pulsatility-index (PI) were measured. The 96 healthy premature born infants showed the following velocities: Vs: 41 +/- 12 cm X sec-1; Ves: 19 +/- 7 cm X sec-1; Ved: 10 +/- 4 cm X sec-1. The pulsatility-index was 0.74 +/- 0.08. In children with PDA all velocities were significantly lower than in the healthy control group: Vs: 31 +/- 10 cm X sec-1; Ves: 7 +/- 6 cm X sec-1; Ved: -1 +/- 5 cm X sec-1. Ved was more decreased than Vs resulting in a significant increase in PI (1.04 +/- 0.14). 22 infants with surgically proven large PDA (age: 31 +/- 3 weeks; birth weight: 1,160 +/- 467 gs) showed significant lower velocities (Vs: 34 +/- 8 cm X sec-1; Ves: 4 +/- 4 cm X sec-1; Ved: -4 +/- 4 cm X sec-1) in comparison with the healthy control group and the 11 children with small PDA (age: 33 +/- 4 weeks; birth weight: 1,494 +/- 621 gs).(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin A: not required for adrenal steroidogenesis in rats.

Previous work supporting the vitamin A dependency of adrenal function in rats neglected to take into account a secondary effect of the deficiency, a decrease in hepatic ascorbic acid biosynthesis. Vitamin A-depleted rats maintained on a diet free of ascorbate had a decrease in the activity of adrenal 3 beta-hydroxysteroid dehydrogenase, and extensive adrenocortical degeneration. The use of an ascorbate supplement prevented the symptoms. The results suggest that previous evidence for direct involvement of vitamin A in steroidogenesis may have been due to the production of a secondary deficiency, a chronic scorbutic condition.