Specific inhibition of nuclear RNA polymerase II by alpha-amanitin.

alpha-Amanitin, a toxic substance from the mushroom Amanita phalloides, is a potent inhibitor of DNA-dependent RNA polymerase II (the nucleoplasmic form) from sea urchin, rat liver, and calf thymus. This compound exerts no effect on the activity of polymerase I (nucleolar form) or polymerase III (also nucleoplasmic). The inhibition is due to a specific interaction with polymerase II or with a complex of DNA and polymerase II.

Articular soft tissue injuries associated with mandibular condyle fractures and the effects on oral function.

The majority of studies debating the optimization of treatment for condylar mandibular fractures focus on the bony aspect first. However, fractures of the mandibular condyle may go together with soft tissue injury of the temporomandibular joint. An electronic literature search for this topic was undertaken. Assessment of quality was carried out using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Sixteen articles were included in this review. The reviewed literature showed that intracapsular fractures and dislocated condylar fractures result in more severe injuries. Serious injury to the disc and capsule of the temporomandibular joint is a contributing factor towards development of complications after closed treatment. The results of this review give an overview of the published studies focusing on articular soft tissue injuries caused by condylar mandibular fractures. Additionally, an overview of the magnetic resonance imaging (MRI) settings used to detect these injuries is provided. Until now, the relation between soft tissue injuries and type of condylar trauma and their influence on clinical outcome has been insufficiently investigated. Before considering reduction of soft tissues next to reduction of the fracture, more research is needed into the impact of soft tissue injuries on oral functioning, in which a uniform classification is used.

A transgenic mouse bearing an antisense construct of regulatory subunit type 1A of protein kinase A develops endocrine and other tumours: comparison with Carney complex and other PRKAR1A induced lesions.

BACKGROUND: Inactivation of the human type Ialpha regulatory subunit (RIalpha) of cyclic AMP dependent protein kinase (PKA) (PRKAR1A) leads to altered kinase activity, primary pigmented nodular adrenocortical disease (PPNAD), and sporadic adrenal and other tumours. METHODS AND RESULTS: A transgenic mouse carrying an antisense transgene for Prkar1a exon 2 (X2AS) under the control of a tetracycline responsive promoter (the Tg(Prkar1a*x2as)1Stra, Tg(tTAhCMV)3Uh or tTA/X2AS line) developed thyroid follicular hyperplasia and adenomas, adrenocortical hyperplasia and other features reminiscent of PPNAD, including late onset weight gain, visceral adiposity, and non-dexamethasone suppressible hypercorticosteronaemia, with histiocytic, epithelial hyperplasias, lymphomas, and other mesenchymal tumours. These lesions were associated with allelic losses of the mouse chromosome 11 Prkar1a locus, an increase in total type II PKA activity, and higher RIIbeta protein levels; the latter biochemical and protein changes were also documented in Carney complex tumours associated with PRKAR1A inactivating mutations and chromosome 17 PRKAR1A locus changes. CONCLUSION: We conclude that the tTA/X2AS mouse line with a downregulated Prkar1a gene replicates several of the findings in Carney complex patients and their affected tissues, supporting the role of RIalpha as a candidate tumour suppressor gene.

Pemoline pharmacokinetics and long term therapy in children with attention deficit disorder and hyperactivity.

The pharmacokinetic behaviour of pemoline was studied in 28 children, aged 5 to 12 years, diagnosed as having the attention deficit disorder with hyperactivity. The mean elimination half-life of pemoline in these children was approximately 7 hours, which is considerably shorter than the half-life of 11 to 13 hours previously reported in adults. The tendency of the half-life to increase with age may be explained by the statistically significant decrease in total body clearance with age. The increasing half-life of pemoline with age should be considered during long term drug therapy. In this study no tolerance to the beneficial effects of pemoline was observed over 6 months. The apparent therapeutic serum concentration range for these children was attained after doses of 37.5 to 131.25 mg pemoline daily. Since the optimum serum concentration shows wide variation, the dosing regimen must be determined individually. Routine monitoring of the pemoline serum concentrations is not useful because of this apparent variation in optimum serum concentration and because of the linear relationship between dose and concentration.

Quantitative GLC determination of codeine in plasma.

A sensitive and accurate GLC method for quantitating codeine in plasma at levels of 50 ng/ml, with limits of detection as low as 5 ng/ml, is described.

Headache as the sole presentation of acute myocardial infarction in two elderly patients.

Myocardial infarction presenting solely as an acute, severe headache is underdiagnosed in elderly patients. In patients over 80 years of age, myocardial infarction presents more commonly with atypical symptoms than with chest pain. The authors describe two patients who presented with headache as the only symptom of an acute myocardial infarction. The authors recommend that acute myocardial infarction be considered in the differential diagnosis of acute, severe headache in elderly patients.

Yeast DNA-dependent RNA polymerase I. A rapid procedure for the large scale purification of homogeneous enzyme.

A procedure has been developed for the rapid purification of large amounts of yeast RNA polymerase I (A). The method involves batchwise treatment with phosphocellulose and DEAE-cellulose, ion filtration chromatography on DEAE-Sephadex, sucrose gradient centrifugation, and DNA-cellulose chromatography. The enzyme obtained is apparently homogeneous by sedimentation velocity analysis and has a specific activity of 300 nmol of UMP incorporated into RNA in 10 min per mg of protein. Between 30 and 45 mg of enzyme can be obtained in 5 days from 3.0 kg of yeast cells. The subunit composition of the enzyme was determined by polyacrylamide gel electrophoresis in the presence of 0.1% sodium dodecyl sulfate. The purified polymerase is composed of 11 putative subunits with molecular weights 185,000 (Ia), 137,000 (Ib), 48,000 (Ic), 44,000 (Id), 41,000 (Ie), 36,000 (If), 28,000 (Ig), 24,000 (Ih), 20,000 (Ii), 14,500 (Ij), and 12,000 (Ik). Yeast polymerase I separates into two forms when subjected to gel electrophoresis under nondenaturing conditions. The main component which migrates faster contains all the subunits except the polypeptides Ic and If. The slow migrating component which is present in lower amounts contains all the subunits.

Structure of yeast phenylalanine-tRNA genes: an intervening DNA segment within the region coding for the tRNA.

Sixteen bacterial clones containing sequences complementary to yeast PhetRNA were isolated from a collection of hybrid plasmids containing BamHI restriction endonuclease-generated yeast DNA fragments inserted in the plasmid vector pBR315. Ten of these clones contained hybrid plasmids with distinct BamHI fragments. The sequence of the Phe-tRNA structural genes and adjacent regions of three of these clones is reported here. In the region flanking the tRNA gene, the sequence of two of the cloned DNAs is similar; the sequence of the third varies considerably. All three of the tRNA genes are bordered by A,T-rich regions. In particular, near the region coding for the 3' end of the tRNA there is a long sequence of As in the coding strand. This is reminiscent of the region of termination of transcription of the yeast 5S rRNA gene. The sequences coding for the Phe-tRNA contain an additional segment of 18 or 19 base pairs (depending upon the clone) not predicted by the yeast Phe-tRNA sequence. These intervening segments are nearly identical in the three clones and are located within the structural gene, two base pairs from the nucleotides coding for the tRNA anticodon.

Molecular structure of yeast RNA polymerase III: demonstration of the tripartite transcriptive system in lower eukaryotes.

Homogeneous RNA polymerase III (RNA nucleotidyltransferase III) has been obtained from yeast. The subunit composition of the enzyme was examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The enzyme is composed of 12 putative subunits with molecular weights 160,000, 128,000, 82,000, 41,000, 40,500, 37,000, 34,000, 28,000, 24,000, 20,000, 14,500, and 11,000. The high-molecular-weight subunits and several of the smaller subunits of yeast RNA polymerase III are clearly different from those of enzymes I and II, indicating a distinct molecular structure. However, the molecular weights of some of the small subunits (41,000, 28,000, 24,000, and 14,500) appear to be identical to those of polymerases I and II. Thus, it is possible that the three classes of enzymes in yeast have some common subunits. As in other eukaryotes, yeast polymerase II is inhibited by relatively low concentrations of alpha-amanitin; however, contrary to what has been found in higher eukaryotes, yeast polymerase III is resistant (up to 2 mg/ml) to alpha-amanitin, while yeast polymerase I is sensitive to high concentrations of the drug (50% inhibition at 0.3 mg/ml). These results establish the existence of RNA polymerase III in yeast and provide a structural basis for the discrimination of the three functional polymerases in eukaryotes.

Ribosomal RNA genes of Saccharomyces cerevisiae. II. Physical map and nucleotide sequence of the 5 S ribosomal RNA gene and adjacent intergenic regions.

A DNA fragment containing the structural gene for the 5 S ribosomal RNA and intergenic regions before and after the 35 S ribosomal RNA precursor gene of Saccharomyces cerevisiae has been amplified in a bacterial plasmid and physically mapped by restriction endonuclease cleavage and hybridization to purified yeast 5 S ribosomal RNA. The nucleotide sequence of the DNA fragments carrying the 5 S ribosomal RNA gene and adjacent regions has been determined. The sequence unambiguously identifies the 5 S ribosomal RNA gene, determines its polarity within the ribosomal DNA repeating unit, and reveals the structure of its promoter and termination regions. Partial DNA sequence of the regions near the beginning and end of the 35 S ribosomal RNA gene has also been determined as a preliminary step in establishing the structure of promoter and termination regions for the 35 S ribosomal RNA gene.

Early use of inhaled nedocromil sodium in children following an acute episode of asthma.

BACKGROUND: Current guidelines on the treatment of childhood asthma recommend the introduction of an anti-inflammatory drug in children who have persistent symptoms and require regular treatment with a bronchodilator. The efficacy and safety of inhaled nedocromil sodium (Tilade Mint aerosol) administered using a Fisonair spacer at a dose of 4 mg three times daily was compared with placebo in the treatment of asthmatic children aged 6-12 years who are symptomatic and recovering from an acute exacerbation of asthma. METHODS: A group comparative, double blind, placebo controlled trial was performed in children who were recovering from an acute episode of asthma following treatment in the emergency department of the hospital or in children referred from their general practitioner following a wheezing episode and documented evidence of at least two previous episodes of wheezing. A two week baseline period on existing bronchodilator treatment was followed by a 12 week treatment period on either nedocromil sodium (2 mg/puff) or placebo. Both treatments were administered using a Fisonair spacer at a dose of two puffs three times daily. Changes from baseline values in daytime asthma and night time asthma symptom scores, usage of rescue bronchodilators, mean peak expiratory flow (PEF) recorded twice daily on diary cards, patients' opinion of treatment, and withdrawals due to treatment failure were measured during the primary treatment period (last six weeks of treatment). RESULTS: One hundred and forty two children aged 6-12 years entered the baseline period. Sixty three were withdrawn due to failure to meet the entry criteria (18) or the criteria for asthma symptom severity (15) or reversibility (9), because they developed uncontrolled asthma (2), because they took disallowed treatment (2), or for other non-trial related reasons (17). Seventy nine patients (46 boys) of mean age 8. 8 years entered the treatment period. There were significant differences in the changes from baseline values during the last six weeks of treatment in favour of nedocromil sodium compared with placebo in the primary variables of daytime asthma and night time asthma, morning and evening PEF, and the usage of rescue inhaled bronchodilators; 53% of patients reported nedocromil sodium to be very or moderately effective compared with 44% placebo. Improvement in asthma symptoms, PEF, and reduction in use of rescue bronchodilators did not reach statistical significance until after six weeks of treatment. Twenty two patients were withdrawn or dropped out during the treatment phase, 12 due to uncontrolled asthma or persistence of asthma symptoms, four due to suspected adverse drug reactions (nedocromil sodium 3 (headaches 2, angio-oedema/urticaria 1), placebo 1(persistent cough)), and six due to non-treatment related reasons. Seventy one adverse events were reported by 27 patients in the nedocromil group and 75 by 30 patients in the placebo group. CONCLUSIONS: Asthma symptoms, use of bronchodilators, and lung function can be improved significantly in children recovering from an acute exacerbation of asthma or wheeze and currently receiving treatment with bronchodilators alone by the addition of inhaled nedocromil sodium at a dose of 4 mg three times daily administered using a Fisonair holding chamber.