Quantifying the impact of initial RNA primer length on nucleotide addition by RNA polymerase I.

Transient state kinetic studies of eukaryotic DNA-dependent RNA polymerases (Pols) in vitro provide quantitative characterization of enzyme activity at the level of individual nucleotide addition events. Previous work revealed heterogeneity in the rate constants governing nucleotide addition by yeast RNA polymerase I (Pol I) for each position on a template DNA. In contrast, the rate constants that described nucleotide addition by yeast RNA polymerase II (Pol II) were more homogeneous. This observation led to the question, what drives the variability of rate constants governing RNA synthesis by Pol I? Are the kinetics of nucleotide addition dictated by the position of the nascent RNA within the polymerase or by the identity of the next encoded nucleotide? In this study, we examine the impact of nucleotide position (i.e. nascent RNA primer length) on the rate constants governing nine sequential nucleotide addition events catalyzed by Pol I. The results reveal a conserved trend in the observed rate constants at each position for all primer lengths used, and highlight that the 9-nucleotide, or 9-mer, RNA primer provides the fastest observed rate constants. These findings suggest that the observed heterogeneity of rate constants for RNA synthesis by Pol I in vitro is driven primarily by the template sequence.

RNA Polymerase I Is Uniquely Vulnerable to the Small-Molecule Inhibitor BMH-21.

Cancer cells require robust ribosome biogenesis to maintain rapid cell growth during tumorigenesis. Because RNA polymerase I (Pol I) transcription of the ribosomal DNA (rDNA) is the first and rate-limiting step of ribosome biogenesis, it has emerged as a promising anti-cancer target. Over the last decade, novel cancer therapeutics targeting Pol I have progressed to clinical trials. BMH-21 is a first-in-class small molecule that inhibits Pol I transcription and represses cancer cell growth. Several recent studies have uncovered key mechanisms by which BMH-21 inhibits ribosome biosynthesis but the selectivity of BMH-21 for Pol I has not been directly measured. Here, we quantify the effects of BMH-21 on Pol I, RNA polymerase II (Pol II), and RNA polymerase III (Pol III) in vitro using purified components. We found that BMH-21 directly impairs nucleotide addition by Pol I, with no or modest effect on Pols II and III, respectively. Additionally, we found that BMH-21 does not affect the stability of any of the Pols' elongation complexes. These data demonstrate that BMH-21 directly exploits unique vulnerabilities of Pol I.

Diabetes in Pregnancy.

OBJECTIVE: This guideline reviews the evidence relating to the diagnosis and obstetrical management of diabetes in pregnancy. OUTCOMES: The outcomes evaluated were short- and long-term maternal outcomes, including preeclampsia, Caesarean section, future diabetes, and other cardiovascular complications, and fetal outcomes, including congenital anomalies, stillbirth, macrosomia, birth trauma, hypoglycemia, and long-term effects. EVIDENCE: Published literature was retrieved through searches of PubMed and the Cochrane Library using appropriate controlled vocabulary (MeSH terms "diabetes" and "pregnancy"). Where appropriate, results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date limits, but results were limited to English or French language materials. VALUES: The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1). SUMMARY STATEMENTS: Recommendations It is recognized that the use of different diagnostic thresholds for the "preferred" and "alternative" strategies could cause confusion in certain settings. Despite this, the committee has identified the importance of remaining aligned with the current Canadian Diabetes Association 2013 guidelines as being a priority. It is thus recommended that each care centre strategically align with 1 of the 2 strategies and implement protocols to ensure consistent and uniform reporting of test results.

Le diabète pendant la grossesse.

OBJECTIF: La présente Directive passe en revue les données probantes liées au diagnostic et à la prise en charge obstétricale du diabète durant la grossesse. ISSUES: Les issues évaluées étaient les issues maternelles à court et à long terme, dont la prééclampsie, la césarienne, le diabète éventuel et d'autres complications cardiovasculaires et les issues fœtales, dont les anomalies congénitales, la mortinaissance, la macrosomie, le traumatisme de la naissance, l'hypoglycémie et les effets à long terme. RéSULTATS: La littérature publiée a été récupérée par l'intermédiaire de recherches menées dans PubMed et The Cochrane Library au moyen d'un vocabulaire contrôlé (termes MeSH « diabète ¼ et « grossesse ¼) appropriés. Le cas échéant, les résultats ont été restreints aux analyses systématiques, aux essais comparatifs randomisés / essais cliniques comparatifs et aux études observationnelles. Aucune limite n'a été imposée en matière de date, mais les résultats ont été limités aux articles publiés en anglais ou en français. VALEURS: La qualité des résultats a été évaluée au moyen des critères décrits dans le rapport du Groupe d'étude canadien sur les soins de santé préventifs (Tableau 1). DéCLARATIONS SOMMAIRES: RECOMMANDATIONS.

Global switch cost as an index for concussion assessment: reliability and stability.

PURPOSE: The objective of this study is to determine the stability and sensitivity of a dual-task (DT) methodology that can be used to assess the effects of concussion in athletes. METHODS: Fifty-nine healthy young adults (Mage = 20.32 ± 1.84 yr, 19 males) who volunteered to participate completed auditory switch tasks that varied in length (30, 40, and 60 items) at baseline, 1 wk later, and approximately 7 months later. During sessions 2 and 3, the participants completed one of three switch tasks while concurrently performing a modified Harvard Step Test. Global switch cost indices and percentage error were calculated for each switch task. The stability reliability of the global switch cost indices was assessed under single-task conditions, and the sensitivity of the global switch costs to interference effects was assessed under DT conditions. RESULTS: The stability reliability was 0.64, 0.84, and 0.83 for the 30-, 40-, and 60-item tests, respectively. ANOVA revealed a main effect for condition (single task vs DT) for both global switch costs (F(1,55) = 44.53, P < 0.0001) and percentage error (F(1,56) = 64.69, P < 0.001). The magnitude of the global switch cost interference effects was nearly identical across the three DT conditions. CONCLUSIONS: The current concussion testing models test athletes' cognitive and physical function in isolation. The stability reliability of the global switch cost index obtained under DT conditions suggests that it may be a useful measure for clinicians. The DT paradigm presents another test methodology that may be useful for making return-to-play decisions as part of a comprehensive concussion management plan.

A rare case of antepartum spontaneous septostomy in a monochorionic diamniotic twin pregnancy.

Spontaneous septostomy in a monochorionic diamniotic twin pregnancy is a rare phenomenon. We present a case of monochorionic diamniotic twin pregnancy with an intact dividing membrane seen in the 1st half of the pregnancy. At 26 weeks, when she was assessed for preterm contractions, the dividing membrane was not documented, which suggested spontaneous septostomy. There had been no invasive procedures during the pregnancy. She subsequently delivered at 29 weeks, secondary to preterm labor. No dividing membrane was noticed at the time of caesarian section. Spontaneous septostomy can complicate the management of monochorionic diamniotic twins by creating a pseudomonoamniotic environment resulting in cord entanglement, and difficulty in the diagnosis and management of twin-twin transfusion syndrome. We believe that such a case should be managed as monochorionic monoamniotic twin gestation.

Correlation of residual amniotic fluid and perinatal outcomes in periviable preterm premature rupture of membranes.

OBJECTIVE: To correlate maternal and fetal outcomes of pregnancies affected by preterm premature rupture of membranes (PPROM) at < 24 weeks' gestational age with the amount of residual amniotic fluid as determined by sonographic evaluation. METHODS: We searched the local maternal-fetal medicine database for the records of all women with PPROM prior to 24 completed weeks of pregnancy. The quantity of residual amniotic fluid determined by ultrasound was recorded and women were separated into two groups: (A) deepest vertical pocket (DVP) ≥ 1 cm, or (B) DVP < 1 cm (severe oligohydramnios). Hospital chart review was undertaken to determine latency to delivery, perinatal death, and maternal complications. Data were analyzed using Fisher exact and Wilcoxon-Mann-Whitney U tests. RESULTS: We identified 31 subjects, of whom nine elected termination of pregnancy (6 in group A, 3 in group B). Six of 10 subjects in group A had a live delivery without neonatal death, whereas only one of 12 subjects in group B had a live delivery (P = 0.020). Additional complications included placental abruption in 63% in group A and 45% in group B, chorioamnionitis in 50% and 70%, respectively, and postpartum endometritis in 0% and 9%, respectively. None of these differences were statistically significant. There were no cases of maternal sepsis or maternal death in either group. Group A was associated with a later GA at delivery (27.5 weeks vs. 23 weeks, P = 0.07), with the GA at rupture of the membranes similar for both groups. CONCLUSION: These results indicate that a higher level of residual amniotic fluid after periviable PPROM is associated with fetal survival and increased latency to delivery without an increase in maternal complications. This information will be valuable in counselling pregnant women with PPROM < 24 weeks.

A rare case of cardiac rhabdomyomas in a dizygotic twin pair.

Cardiac rhabdomyoma (CR) is the cardiac tumour most commonly diagnosed in utero. Eighty percent of CRs are associated with tuberous sclerosis (TS). TS is a rare multi-system disease, with autosomal dominant genetic transmission. If the parents of an affected child do not have features of TS, then either one parent is mosaic for the TS gene mutation or the affected child is the result of a de novo germline mutation. We present a case of a dizygotic twin pregnancy complicated by CRs in both fetuses at 24 weeks. Twin A died in utero at 28 weeks. Preterm labour and delivery of twin B occurred at 33 weeks. Twin B had multiple small CRs and a large apical CR. At six weeks after delivery, the CRs had disappeared or reduced in size. Regression in the third trimester or postnatally is the natural course of CRs. Molecular testing for TS identified two variants in the TSC2 gene. The parents were clinically unaffected; however, the father was subsequently found on an MRI of the head to have cortical tubers, and he was found to carry the pathogenic TSC2 mutation. Since dizygotic twin pregnancy is akin to two consecutive pregnancies, the etiology in our case is due to one parent having subclinical TS. To the best of our knowledge, this is the first such case to be reported.

The assessment of attention-deficit/hyperactivity disorder in rural primary care: the portability of the American Academy of Pediatrics guidelines to the "real world".

OBJECTIVE: To examine the implementation of a protocol for the assessment of attention-deficit/hyperactivity disorder (ADHD) in rural pediatric practices. The protocol was designed to provide an efficient means for pediatricians to learn and use the ADHD guidelines put forth by the American Academy of Pediatrics (AAP). METHODS: Primary care staff (physicians, nurses, etc) from 2 rural pediatric practices were trained to use the ADHD-assessment protocol. Medical records for 101 patients were reviewed from 1 to 2 years before the introduction of the protocol and for 86 patients during the subsequent 2 to 3 years to assess compliance with the AAP guidelines. In addition, 34% of the scales scored by the staff were rescored to check for scoring accuracy. RESULTS: Before the availability of the AAP guidelines and the implementation of the assessment protocol, neither primary care site was consistently collecting the comprehensive information that is now recommended for an ADHD assessment. Parent and/or teacher rating scales were collected for only 0% to 21% of assessments across sites. When provided with brief training and supporting materials, medical records reflected significant improvement in the ascertainment of clinically necessary ADHD information, with parent and teacher rating scales present 88% to 100% of the time. Staff demonstrated an ability to score rating scales with a high degree of accuracy. The integrity of protocol collection and management was maintained 2 to 3 years after training. CONCLUSIONS: An efficient system for conducting ADHD assessments according to AAP guidelines in rural pediatrics clinics can be initiated and maintained with integrity. Additional research is needed to determine if this system improves diagnostic decision-making and patient outcomes.