Analysis of Saccharomyces cerevisiae his3 transcription in vitro: biochemical support for multiple mechanisms of transcription.

The promoter region of the Saccharomyces cerevisiae his3 gene contains two TATA elements, TC and TR, that direct transcription initiation to two sites designated +1 and +13. On the basis of differences between their nucleotide sequences and their responsiveness to upstream promoter elements, it has previously been proposed that TC and TR promote transcription by different molecular mechanisms. To begin a study of his3 transcription in vitro, we used S. cerevisiae nuclear extracts together with various DNA templates and transcriptional activator proteins that have been characterized in vivo. We demonstrated accurate transcription initiation in vitro at the sites used in vivo, transcriptional activation by GCN4, and activation by a GAL4 derivative on various gal-his3 hybrid promoters. In all cases, transcription stimulation was dependent on the presence of an acidic activation region in the activator protein. In addition, analysis of promoters containing a variety of TR derivatives indicated that the level of transcription in vitro was directly related to the level achieved in vivo. The results demonstrated that the in vitro system accurately reproduced all known aspects of in vivo his3 transcription that depend on the TR element. However, in striking contrast to his3 transcription in vivo, transcription in vitro yielded approximately 20 times more of the +13 transcript than the +1 transcript. This result was not due to inability of the +1 initiation site to be efficiently utilized in vitro, but rather it reflects the lack of TC function in vitro. The results support the idea that TC and TR mediate transcription from the wild-type promoter by distinct mechanisms.

Promoter-specific shifts in transcription initiation conferred by yeast TFIIB mutations are determined by the sequence in the immediate vicinity of the start sites.

The general transcription factor IIB (TFIIB) is required for transcription of class II genes by RNA polymerase II. Previous studies demonstrated that mutations in the Saccharomyces cerevisiae SUA7 gene, which encodes TFIIB, can alter transcription initiation patterns in vivo. To further delineate the functional domain and residues of TFIIB involved in transcription start site utilization, a genetic selection was used to isolate S. cerevisiae TFIIB mutants exhibiting downstream shifts in transcription initiation in vivo. Both dominant and recessive mutations conferring downstream shifts were identified at multiple positions within a highly conserved homology block in the N-terminal region of the protein. The TFIIB mutations conferred downstream shifts in transcription initiation at the ADH1 and CYC1 promoters, whereas no significant shifts were observed at the HIS3 promoter. Analysis of a series of ADH1-HIS3 hybrid promoters and variant ADH1 and HIS3 promoters containing insertions, deletions, or site-directed base substitutions revealed that the feature that renders a promoter sensitive to TFIIB mutations is the sequence in the immediate vicinity of the normal start sites. We discuss these results in light of possible models for the mechanism of start site utilization by S. cerevisiae RNA polymerase II and the role played by TFIIB.

The glutamine-rich activation domains of human Sp1 do not stimulate transcription in Saccharomyces cerevisiae.

Eukaryotic transcriptional activators have been classified on the basis of the characteristics of their activation domains. Acidic activation domains, such as those in the yeast GAL4 or GNC4 proteins and the herpes simplex virus activator VP16, stimulate RNA polymerase II transcription when introduced into a variety of eukaryotic cells. This species interchangeability demonstrates that the mechanism by which acidic activation domains function is highly conserved in the eukaryotic kingdom. To determine whether such a conservation of function exists for a different class of activation domain, we have tested whether the glutamine-rich activation domains of the human transcriptional activator Sp1 function in the yeast Saccharomyces cerevisiae. We report here that the glutamine-rich domains of Sp1 do not stimulate transcription in S. cerevisiae, even when accompanied by human TATA-box binding protein (TBP) or human-yeast TATA-box binding protein hybrids. Thus, in contrast to the case for acidic activation domains, the mechanism by which glutamine-rich domains stimulate transcription is not conserved between S. cerevisiae and humans.

Mutational analysis of the D1/E1 core helices and the conserved N-terminal region of yeast transcription factor IIB (TFIIB): identification of an N-terminal mutant that stabilizes TATA-binding protein-TFIIB-DNA complexes.

The general transcription factor IIB (TFIIB) plays an essential role in transcription of protein-coding genes by RNA polymerase II. We have used site-directed mutagenesis to assess the role of conserved amino acids in several important regions of yeast TFIIB. These include residues in the highly conserved amino-terminal region and basic residues in the D1 and E1 core domain alpha-helices. Acidic substitutions of residues K190 (D1) and K201 (E1) resulted in growth impairments in vivo, reduced basal transcriptional activity in vitro, and an inability to form stable TFIIB-TATA-binding protein-DNA (DB) complexes. Significantly, these mutants retained the ability to respond to acidic activators in vivo and to the Gal4-VP16 activator in vitro, supporting the view that these basic residues play a role in basal transcription. In addition, 14 single-amino-acid substitutions were introduced in the conserved amino-terminal region. Three of these mutants, the L50D, R64E, and R78L mutants, displayed altered growth properties in vivo and were compromised for supporting transcription in vitro. The L50D mutant was impaired for RNA polymerase II interaction, while the R64E mutant exhibited altered transcription start site selection both in vitro and in vivo and, surprisingly, was more active than the wild type in the formation of stable DB complexes. These results support the view that the amino-terminal domain is involved in the direct interaction between yeast TFIIB and RNA polymerase II and suggest that this domain may interact with DNA and/or modulate the formation of a DB complex.

Paediatric eosinophilic oesophagitis: towards early diagnosis and best treatment.

UNLABELLED: Eosinophilic oesophagitis is an emerging disease, well known also in paediatric age, probably caused by both IgE and non-IgE mediated food allergies, diagnosed by upper endoscopy with biopsy. The most severe complication is oesophageal stenosis. The identification of the offending allergens is often difficult; therapy is focused to eliminate the supposed antigenic stimulus, to control the acute symptoms and to induce long-term remission. AIM: We report the clinical outcome and the typical endoscopic findings of children and adolescents affected by eosinophilic oesophagitis, referring a proposal of diagnostic and treatment protocol. PATIENTS AND METHODS: Twelve patients, affected by eosinophilic oesophagitis with a histological diagnosis, underwent radiographic upper gastro-intestinal series, 24 h pH-probe and standardised allergic testing; they were treated with steroids (oral prednisone and swallowed aerosolised fluticasone) and elimination diet. Dilations were performed when eosinophilic oesophagitis was not yet diagnosed, or in patients resistant to conventional treatment. RESULTS: Two patients were lost to follow up (mean follow up: 1 year 11 months); seven patients have no symptoms and normal histology, five of them on restricted diet (without cow's milk protein) and two patients on elemental diet (amino acid formula). In two patients (no allergens identified), mild dysphagia and eosinophilic infiltration persist; one patients underwent Nissen fundoplication for Barrett's oesophagus: he has no symptoms and normal oesophagus, on restricted diet (without cow's milk/eggs protein and wheat). CONCLUSION: The recognition of typical endoscopic picture with careful biopsies extended to the whole oesophagus, even in emergency, could more quickly lead to the correct diagnosis and avoid severe complications of eosinophilic oesophagitis in children, as stricture and failure to growth. Elimination diet is the key of resolution when the allergens are identified. A great challenge remains the relation between gastro-oesophageal reflux disease and eosinophilic oesophagitis, which should however be explained.

Meiotic recombination-deficient mutants of Schizosaccharomyces pombe.

A mutant screen employing the ade6-M26 recombination hotspot was developed and used to isolate Schizosaccharomyces pombe mutants deficient in meiotic recombination. Nine rec mutations were recessive, defining six complementation groups, and reduced ade6 meiotic recombination 3-fold to greater than or equal to 300-fold when homozygous. Three recessive rec mutations analyzed further also reduced meiotic intragenic recombination at ura4 on chromosome III and intergenic recombination between pro2 and arg3 on chromosome I. The observed non-co-ordinate reductions of the recombinant frequencies in the three test intervals suggest a degree of locus (or intragenic vs. intergenic) specificity of the corresponding rec+ gene products. None of the mutations specifically inactivated the ade6-M26 hotspot. Additional rec genes may be identified with these methods.

Genetic and physical analysis of the M26 recombination hotspot of Schizosaccharomyces pombe.

The ade6-M26 mutation of Schizosaccharomyces pombe has previously been reported to stimulate ade6 intragenic meiotic recombination. We report here that the ade6-M26 mutation is a single G----T nucleotide change, that M26 stimulated recombination within ade6 but not at other distinct loci, and that M26 stimulated meiotic but not mitotic recombination. In addition, M26 stimulated recombination within ade6 when M26 is homozygous; this result demonstrates that a base-pair mismatch at the M26 site was not required for the stimulation. These results are consistent with the ade6-M26 mutation creating a meiotic recombination initiation site.

The effect of bone morphogenetic protein-7 on the expression of type I inositol 1,4,5-trisphosphate receptor in G-292 osteosarcoma cells and primary osteoblast cultures.

Bone morphogenetic protein-7 (BMP-7) affects differentiation of preosteoblasts enabling the resultant cells to respond optimally to acutely acting regulators. As the phosphoinositide cascade and, particularly, the calcium-mobilizing inositol 1,4,5-trisphosphate (InsP3) receptor are integral to stimulus-secretion coupling in osteoblasts, the hypothesis that BMP-7 affects InsP3 receptor expression was examined in the G-292 human osteosarcoma cell line and in primary cultures of human osteoblasts. G-292 osteosarcoma cells were found to be a valid experimental model for primary human osteoblasts, expressing osteoblastic mRNAs encoding osteocalcin, bone sialoprotein, alkaline phosphatase, alpha1-collagen, epidermal growth-factor receptor, and BMP type II receptor. When cultured long term in the presence of ascorbic acid and beta-glycerophosphate, G-292 cells underwent further osteoblastic differentiation, forming nodules and exhibiting restricted mineralization. G-292 cells responded to BMP-7 with an increase in InsP3 receptor density. Ligand-binding studies established that BMP-7 (50 ng/ml) treatment of G-292 cells increased InsP3 receptor density 2.4-fold with no apparent change in affinity. Immunoblot analysis with antibodies specific for type I, type II, and type III InsP3 receptors revealed that BMP-7 (50 ng/ml) treatment resulted in a specific increase (206+/-8%) in the type I receptor. Reverse transcription-polymerase chain reaction and Northern blot analyses of G-292 and primary human osteoblasts confirmed an increase in type I InsP3 receptor mRNA upon BMP-7 treatment. These results demonstrate that G-292 cells respond to BMP-7 with an increase InsP3 receptor density, consistent with the enhanced capacity of these cells to respond to Ca2+-mobilizing secretory hormones during osteoblast differentiation.

Preliminary report of electrogastrography in pediatric gastroresection: can it be predictive of alteration of gastric motility?

BACKGROUND/PURPOSE: Gastric resection is an infrequent surgical procedure in childhood. However, the use of the stomach for bladder augmentation and substitution is well documented. Partial gastrectomy performed in gastrocystoplasty (GCP) involves the greater curvature of the stomach, the same area in which gastric pace-maker cells are known to be placed. The aim of this study was to assess, by electrogastrography (EGG), if subtotal gastric resection can alter gastric motility in children submitted to partial gastrectomy for GCP. METHODS: Gastric electrical activity (GEA) was evaluated in 25 children using EGG: 10 patients (4 boys, 6 girls; mean age, 11.6 years) previously submitted to GCP, and 15 normal subjects (12 boys, 3 girls; mean age, 8.62 +/- 2.77 years) as controls. All patients were submitted to cutaneous EGG; recording GEA for 30 minutes before and after a standard test meal. The percentage of 3 cycles per minute (3CPM), bradygastria, tachygastria, DFIC (dominant frequency instability coefficient), DPIC (dominant power instability coefficient), PDP (period dominant power), PDF (period dominant frequency) were recorded and analyzed using Wilcoxon matched-pair test. Data were considered statistically significant if P <.05. RESULTS: Normal subjects as well as operated patients showed a statistically significant difference in bradygastria (P =.05), PDP and PDF (P =.05) percentage, comparing pre versus postprandial period. In the normal group, 3CPM (P =.0012) and DFIC (P =.0008) were statistically different between the pre- and postprandial period. Patients who underwent GCP did not show any statistically significant difference in 3CPM and DFIC pre- and postprandial. CONCLUSIONS: In normal subjects, GEA showed a complete variation after the meal, whereas in operated patients GEA was impaired and only partially modified after the meal. This observation suggests that in patients with gastric resection, adaptation of the stomach to food ingestion is present but incomplete with respect to normal subjects; it can be caused by surgical removal of the pace-maker cells of the greater curvature. For this reason a follow-up analysis of gastric function is recommended for all patients undergoing GCP.

Stenting for caustic strictures: esophageal replacement replaced.

METHODS: From 1983 to 1996, 31 children with caustic esophageal strictures were seen at Bambino Gesù Children's Hospital; they were all treated conservatively except for two cases complicated by tracheoesophageal fistula. The remaining 29 patients were divided into three groups depending on the treatment, which was modified over the years. Group A (1983 to 1987) consisted of seven patients treated by periodic dilatations; group B (1988 to 1992) consisted of 10 children treated by 40 days of esophageal stenting plus dexamethasone, 0.5 mg/kg/d plus ranitidine plus no oral feeding for 7 to 10 days; group C (1993 to 1996) consisted of 12 cases treated by 40 days of esophageal stenting plus dexamethasone, 1 mg/kg/d plus omeprazole plus early oral feeding resumption. RESULTS: No differences were observed between the three groups of patients with regard to the mean age and to the ingested substance, whereas a significant difference (P = .007) was observed in the mean length of the stricture between group A and C (3.4+/-1.3 and 5.6+/-1.6 cm, respectively). In all but one of the patients (96.5%) complete healing of the stenosis was achieved by conservative treatment, with definitive relief of dysphagia. One patient in group C did not improve after a repeated stenting procedure and was surgically treated. However, in group A, resolution of the stricture was obtained after an average of 19.9+/-14.8 dilatations in a mean period of 25.3+/-17.2 months. In group B, a mean of 12+/-11.3 dilatations were required in a mean period of treatment of 14.1+/-10.6 months. In patients in group C, a mean of 3.5+/-3.2 dilatations were necessary in a mean of 5.8+/-4.8 months. A statistically significant difference was observed both with regard to the number of dilatations and to the duration of treatment, between group A and group C (P = .002) and group B and C (P = .03). CONCLUSION: Esophageal replacement should be considered only in cases complicated by tracheoesophageal fistula or in the rare patients who do not respond to repeated esophageal stenting.

Role of electrogastrography in detecting motility disorders in children affected by chronic intestinal pseudo-obstruction and Crohn's disease.

Gastrointestinal motility disorders are frequently found in several pathologies. The aim of this study was to assess, by means of electrogastrography, the presence of gastrointestinal motility abnormalities in children affected by Crohn's disease (CD) or Chronic Intestinal Pseudo-Obstruction (CIPO). Patients and Methods. We studied 34 subjects; 20 control subjects (M = 15, mean age = 10 +/- 3.5 yrs), 8 patients (M = 4, mean age = 18 +/- 7 yrs) with Crohn's disease in a quiescent phase and 6 patients (M = 6, mean age = 10 +/- 3.5 yrs) with Chronic Intestinal Pseudo-Obstruction. Results. Analysis of gastric electrical activity (GEA) parameters demonstrated that in the control group physiological post-prandial changes are represented by an increase of 3 Cycles Per Minute (3 CPM) activity, Period Dominant Power (PDP) and Period Dominant Frequency (PDF) and by the reduction of bradygastria. Crohn patients showed an insignificant increase of 3 CPM and PDP; CIPO patients showed an abnormal variation of 3 CPM, PDP and post-prandial bradygastria. Moreover, CD patients showed a significant difference in post-prandial values of PDP compared to normal subjects. CIPO patients revealed a significant difference in the values of either preprandial PDF with tachygastria or the post-prandial value of 3 CPM, compared to normal subjects. Conclusions. EEG is a non-invasive method to study gut motility related to GEA alterations present in CIPO as well as in CD patients.

Ulcerative colitis in children under 10 years of age: medical and surgical treatment.

Ulcerative colitis is seen with increasing frequency in paediatric age and its diagnosis is made more difficult by atypical cases. Sixty-five patients with UC were seen at our institute and all of them underwent medical treatment. In all patients the disease extended to the whole colon (pancolitis). Eleven patients (average age 9 yrs) underwent surgical correction by Endorectal Pull Through (EPT) 8 straight and 3 with ileal reservoir. One straight EPT had to be converted to Brooke ileostomy because of unacceptable stool frequency. In the rest of the patients the disease is well controlled with medical treatment. After 2 years of follow up surgical complications, continence, stool frequency and quality of life were evaluated: results indicate that surgical complications rate is the same as in other reported series; furthermore, continence and stool frequency are good with all surgical techniques eve though straight pull-through may require a period of adaptation the length of which varies considerably. Our results confirm that children with pancolitis and severe symptoms should be offered prolonged medical treatment prior to undertake surgical correction.

Mesosigmoidoplasty in the treatment of sigmoid volvulus in children.

Sigmoid volvulus is a rare disease of childhood, which requires surgery. The case of a 12-year-old boy is reported. The main aetiopathogenetic causes and the proper surgical approach are also described with particular reference to the so-called mesosigmoidoplasty, which consists of shortening the mesosigmoid by incision along its axis and transverse suture.

[pH-metric parameters potentially predictive of asthmatic symptomatology: clinical and statistical research]. / Parametri pH-metrici potenzialmente predittivi della sintomatologia asmatica: ricerca clinica e statistica.

The gastro-esophageal reflux (GER) usually causes digestive symptoms, failure to trive and/or respiratory symptoms. Furthemore the association between GER and asthma is well known. Nevertheless, the relationship between two pathologies and role of GER in aggravation of asthma are not well known. The aims of our study is to identify the peculiar pH-metric caracteristics of GER may be responsable of asthmatic symptoms in children. The study was conducted in 32 children. The patients were divided into two groups: Group A composed of 16 children suffering from non-allergic asthma characterized by prevalent nocturnal manifestation; Group B composed of 16 children suffering from GER, without respiratory symptoms. All patients underwent to 21 pH-monitoring. The pH-metric data collected in two groups are submitted to statistic analysis using the Student's "t" Test.

[Stenosis of the colon in childhood]. / La stenosi del colon in età pediatrica.

The authors report 6 cases of colonic stenosis (three males and three females, range of age 9 days-4 months) observed from 1982 to 1985 in the Department of Pediatric Surgery in Bambino Gesù Hospital. Three out of six have been admitted with the diagnosis of necrotizing enterocolitis soon after birth. The authors have observed 2 cases of colonic stenosis in neonatal age, 1 case aged month, both suffering from Hirschsprung's disease. A file for the diagnosis has been performed for all patients. Stenosis have been observed in the descending colon, sigmoid colon, rectosigmoid tract, multiple stenosis were present in 2 patients. In 5 patients the surgical treatment has been the removal of stenotic tract. In three patients a colostomy on transverse colon has been performed followed by abdominal perineal intestinal lowering. The authors stress the importance of anorectal manometry among investigations usually performed to exclude Hirschsprung's disease.

[Accidents in childhood. Experiences at the Emergency Department of the Bambino Gesù Hospital of Rome]. / Gli infortuni in età pediatrica. L'esperienza del Servizio di Accettazione e Soccorso dell'Ospedale "Bambino Gesù" di Roma.

Considering the clinical and statistical data about injured children coming to the emergency department in the years between 1990 and 1995, the Authors hope better information, identification of risks, use of safety devices in order to successfully implement precautionary measures and the assistance in accidents which still are the first reason for death in children.

Chromosomal context dependence of a eukaryotic recombinational hot spot.

The single base-pair mutation M26 in the ade6 gene of the fission yeast Schizosaccharomyces pombe creates a hot spot for meiotic homologous recombination. When DNA fragments containing M26 and up to 3.0 kilobases of surrounding DNA were moved to the ura4 gene or to a multicopy plasmid, M26 had no detectable hot spot activity. Our results indicate that nucleotide sequences at least 1 kilobase away from M26 are required for M26 hot spot activity and suggest that, as for transcriptional promoters, a second site or proper chromatin structure is required for activation of this eukaryotic recombinational hot spot. We discuss the implications of these results for studies of other meiotic recombinational hot spots and for gene targeting.