[Functional constipation: prospective study and treatment response]. / Estreñimiento funcional: estudio prospectivo y respuesta al tratamiento.

OBJECTIVE: To assess the prevalence of functional constipation (FC) with and without encopresis, the factors involved in its onset, and treatment response. PATIENTS AND METHODS: A prospective study of 62 children was performed using a standard questionnaire (onset-age, regular toilet use, encopresis, complications, dietary habits and environmental and psychological factors) and physical and anthropometric assessment. FC was defined as a stool frequency of less than 3 bowel movements/week, with passage of large or scybalous stools, with or without 2 or more soiling episodes per week, without underlying disease. Treatment included demystification, behavioral modification and drugs (mineral oil and senna). Each child was periodically re-evaluated, and treatment was considered successful when the defecation rate was 3 or more bowel movements/week, discomfort was absent, and fecal soiling frequency was 2 or fewer episodes/ month. RESULTS AND CONCLUSIONS: FC accounted for 13 % of all first consultations (60 % boys, 40 % girls; mean age at diagnosis 6.1 years). The most frequent manifestations were painful defecation (60 %), rectorrhagia (42 %), obstructive episodes (34 %) and anal fissure or hemorrhoids (17 %); 19 patients (31 %) had encopresis. Nutritional assessment revealed that 84 % of the patients was well nourished and 16 % was overweight. Fiber intake was deficient in more than 60 %. Sixteen (26 %) patients underwent successful relief of impaction with senna (20-30 mg/dose) combined with mineral oil. Maintenance treatment included mineral oil (15-30 ml/day) and senna at the minimum effective dose (5-15 mg/day). Satisfactory results were achieved 1 month later in 32 % of the children, 3-6 months later in 71 %, and 6-12 months later in 85 %; successful response was closely related to regular toilet habits, dietary modification and a shift in the family's attitude.

Effect of the deletion of upstream DNA sequences on expression from the ilvGp2 promoter of the ilvGMEDA operon of Escherichia coli K-12.

Transcription in vitro of the regulatory region of the ilvGMEDA operon yields two attenuated RNAs initiated from the tandem promoters ilvGp1 and ilvGp2. Both S1 nuclease analysis and the fusion of ilvGp1 to galK indicate that transcription is not initiated in vivo from ilvGp1. However deletion of DNA sequences 150 to 100 bp upstream of ilvGp2 drastically reduces expression in vivo from ilvGp2. Both the distance separating ilvGp2 from the upstream DNA sequences and their relative orientation to each other on the DNA helix affect expression from ilvGp2. Deletion of DNA sequences approximately 400 bp upstream of ilvGp2 increases expression in vivo from this promoter. Analysis of products of transcription in vitro indicates that the effects observed in vivo are probably not due to DNA conformation or interactions of RNA polymerase.

Binding of integration host factor (IHF) to the ilvGp1 promoter of the ilvGMEDA operon of Escherichia coli K12.

Crude extracts of Escherichia coli K-12 were found to bind DNA restriction fragments containing ilvGp1. Our analysis using a series of restriction fragments and a BamHI linker mutation indicate that a factor binds to ilvGp1 or adjacent to it. Analysis with mutant strains of E. coli K-12 and purified IHF indicate that IHF binds to ilvGp1. Furthermore, both analysis in vivo and in vitro indicate that IHF precludes transcription from ilvGp1.

Analysis of regulation of the ilvGMEDA operon by using leader-attenuator-galK gene fusions.

Five of the genes for the biosynthesis of isoleucine and valine form the ilvGMEDA operon of Escherichia coli K-12. Expression of the operon responds to changes in the availability of isoleucine, leucine, and valine (ILV). Addition of an excess of all three amino acids results in reduced expression of the operon, whereas limitation for one of the three amino acids causes an increase in expression. The operon is preceded by a leader-attenuator which clearly regulates the increased expression that occurs due to reduced aminoacylation of tRNA. To assess the factors that result in the reduced expression of this operon upon the addition of ILV, a series of plasmids were constructed in which the ilv regulatory region was fused to galK. In response to addition of the amino acids, expression of the galK gene fused to the leader-attenuator decreased five- to sevenfold, instead of the twofold observed for the chromosomal operon. A deletion analysis with these plasmids indicated that the ILV-specific decrease in expression required an intact leader-attenuator but not ilvGp2 or the DNA that precedes this promoter. This conclusion was supported by both S1 nuclease analysis of transcription initiation and determination of galK mRNA levels by RNA-RNA hybridization.