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PubMed1992

Protein splicing removes intervening sequences in an archaea DNA polymerase.

The Vent DNA polymerase gene from Thermococcus litoralis contains two in-frame insertions that must be spliced out to form the mature polymerase. Primer extension and cDNA PCR revealed no evidence of spliced RNA to account for this editing. In contrast, pulse-chase analysis indicated that expression constructs lacking the first insertion produced a protein precursor in Escherichia coli that was processed post-translationally to form polymerase and I-TliI, the endonuclease protein that is the product of the second insertion. At least one intermediate, which migrated more slowly than the precursor and may be branched, was also detected. Amino acid substitutions at the splice junction slowed or blocked the protein splicing reaction. Processing occurs in several heterologous systems, indicating either self-splicing or ubiquitous splicing factors. Processing occurs in a mutant lacking I-TliI endonuclease activity, establishing the independence of splicing and endonuclease activities.

Amino Acid Sequence↗

PubMed1999

Relevance of accurate Monte Carlo modeling in nuclear medical imaging.

Monte Carlo techniques have become popular in different areas of medical physics with advantage of powerful computing systems. In particular, they have been extensively applied to simulate processes involving random behavior and to quantify physical parameters that are difficult or even impossible to calculate by experimental measurements. Recent nuclear medical imaging innovations such as single-photon emission computed tomography (SPECT), positron emission tomography (PET), and multiple emission tomography (MET) are ideal for Monte Carlo modeling techniques because of the stochastic nature of radiation emission, transport and detection processes. Factors which have contributed to the wider use include improved models of radiation transport processes, the practicality of application with the development of acceleration schemes and the improved speed of computers. In this paper we present a derivation and methodological basis for this approach and critically review their areas of application in nuclear imaging. An overview of existing simulation programs is provided and illustrated with examples of some useful features of such sophisticated tools in connection with common computing facilities and more powerful multiple-processor parallel processing systems. Current and future trends in the field are also discussed.

Algorithms↗

PubMed2001

A dermal model for spray painters. Part I: subjective exposure modelling of spray paint deposition.

The discriminative power of existing dermal exposure models is limited. Most models only allow occupational hygienists to rank workers between and within workplaces according to broad bands of dermal exposure. No allowance is made for the work practices of different individuals. In this study a process-based, structured approach has been used to estimate dermal exposure from overspray generated by a spray painting process. Factors for spray technique, object shape and workers' individual work practices involved in the processes of droplet formation and deposition were incorporated into the model. The model was applied to predict dermal exposure of airless spray painters and the results were compared with exposure data. The predicted levels of exposure showed reasonable rank correlation with the measured exposure, although the model tended to over-predict the actual level of exposure. It was concluded that a structured, process-based approach has the potential to produce reliable estimates of dermal exposure. The reliability of exposure models of this type should be explored further and the relationship between the determinants of exposure should be validated by additional field studies.

Air Pollutants, Occupational↗

PubMed1996

Isolation of a heat-labile protein factor involved in the 3'-processing of H4 pre-mRNA.

It is well documented that the snRNP particles play a role in the processing of histone pre-mRNAs. There is also evidence that in addition to the snRNP particles, at least two more proteins are involved in the vitro 3'-processing of histone pre-mRNAs. The aim of the present work was the isolation and purification of one of these PF250 factors. Processing factor PF250 was isolated from HeLa nuclear extracts using ion exchange chromatography. Its ability to partially restore the processing activity of heat inactivated nuclear extract was demonstrated in vitro using labelled H4- pre-mRNA. Our results indicate that nuclear extracts exposed to 50 degrees C for 15 min lacked any processing activity. Using a series of column chromatography purification steps we isolated a thermolabile protein factor that partially restored the activity of heat inactivated HeLa cell nuclear extracts. It can be concluded that besides U7 snRNP particles at least one more thermolabile protein factor is required for the maturation of H4 pre-mRNA in vitro. It has a molecular mass of 30 kDa and is inactivated by heating at 50 degrees C. These characteristics make it a likely candidate to be a regulatory factor involved in pre-mRNA processing.

HeLa Cells↗

PubMed1998

[Critical thinking among nurses during unit-based quality assurance projects].

The purposes of this study were to describe the objectives and levels of critical thinking among nurses during unit-based quality assurance projects and the meaning of the participation for their own development and nursing practice. The data were collected by interviewing ten nurses who had taken part in the quality assurance projects. The themes used in interviews were created on the basis of two open questions answered by 28 nurses. The data were analysed by using qualitative content analysis and applying the levels of reflective thinking developed by Mezirow (1981), Goodman (1984) and Järvinen (1990). The first level of critical thinking was defined as technical thinking, the second level as reflective thinking and the third level as critical reflection. The results showed that nurses reflected the structural factors of the quality assurance on the technical level. When reflecting their own quality assurance processes (process factors) nurses used their critical thinking on all levels. Very few nurses considered the outcome factors of the quality assurance, but when they focused their thinking on the outcomes the reflection reached all levels. The nurses reflected the meaning of the quality assurance projects on all three levels. According to the nurses, the quality assurance enhanced their professional abilities as well as motivation in work and self-esteem. The quality assurance projects also clarified the principles guiding nursing practice. Interaction between nurses, patients and colleagues became more open.

Attitude of Health Personnel↗

PubMed1999

Specificity determinants of proteolytic processing of Aspergillus PacC transcription factor are remote from the processing site, and processing occurs in yeast if pH signalling is bypassed.

The Aspergillus nidulans transcription factor PacC, which mediates pH regulation, is proteolytically processed to a functional form in response to ambient alkaline pH. The full-length PacC form is unstable in the presence of an operational pH signal transduction pathway, due to processing to the relatively stable short functional form. We have characterized and used an extensive collection of pacC mutations, including a novel class of "neutrality-mimicking" pacC mutations having aspects of both acidity- and alkalinity-mimicking phenotypes, to investigate a number of important features of PacC processing. Analysis of mutant proteins lacking the major translation initiation residue or truncated at various distances from the C terminus showed that PacC processing does not remove N-terminal residues, indicated that processing yields slightly heterogeneous products, and delimited the most upstream processing site to residues approximately 252 to 254. Faithful processing of three mutant proteins having deletions of a region including the predicted processing site(s) and of a fourth having 55 frameshifted residues following residue 238 indicated that specificity determinants reside at sequences or structural features located upstream of residue 235. Thus, the PacC protease cuts a peptide bond(s) remote from these determinants, possibly thereby resembling type I endonucleases. Downstream of the cleavage site, residues 407 to 678 are not essential for processing, but truncation at or before residue 333 largely prevents it. Ambient pH apparently regulates the accessibility of PacC to proteolytic processing. Alkalinity-mimicking mutations L259R, L266F, and L340S favor the protease-accessible conformation, whereas a protein with residues 465 to 540 deleted retains a protease-inaccessible conformation, leading to acidity mimicry. Finally, not only does processing constitute a crucial form of modulation for PacC, but there is evidence for its conservation during fungal evolution. Transgenic expression of a truncated PacC protein, which was processed in a pH-independent manner, showed that appropriate processing can occur in Saccharomyces cerevisiae.

Amino Acid Sequence↗

PubMed1999

RNA polymerase II localizes at sites of human cytomegalovirus immediate-early RNA synthesis and processing.

Pre-mRNA synthesis in eukaryotic cells is preceded by the formation of a transcription initiation complex and binding of unphosphorylated RNA polymerase II (Pol II) at the promoter region of a gene. Transcription initiation and elongation are accompanied by the hyperphosphorylation of the carboxy-terminal domain (CTD) of Pol II large subunit. Recent biochemical studies provided evidence that RNA processing factors, including those required for splicing, associate with hyperphosphorylated CTDs forming "transcription factories." To directly visualize the existence of such factories, we simultaneously detected human cytomegalovirus immediate-early (IE) DNA and RNA with splicing factors and Pol II in rat 9G cells inducible for IE gene expression. Combined in situ hybridization and immunocytochemistry revealed that, after induction, both splicing factors and Pol II are present at the sites of IE mRNA synthesis and of IE mRNA processing that extend from the transcribing gene. Noninduced cells revealed no such associations. When IE mRNA-synthesizing cells were treated with a transcription inhibitor, these associations disappeared within 30 min. Our results show that the association of Pol II and splicing factors with IE DNA is dependent on its transcriptional activity and furthermore suggest that splicing factors are still associated with Pol II during active splicing.

Animals↗

PubMed2001

Nascent ribosomes.

The conversion of a ribosomal RNA transcript to a cytoplasmic ribosome requires hundreds of accessory RNA and protein factors. Two papers published recently in Molecular Cell provide first looks at the association of these processing factors with the intermediates in ribosome synthesis (Harnpicharnchai et al., 2001; Bassler et al., 2001).

Cytoplasm↗

PubMed1999

Identification, sequence analysis and phylogeny of the lef-2 gene of Helicoverpa armigera single-nucleocapsid baculovirus.

The baculovirus late expression factor 2 (LEF-2) is involved in DNA replication, and most likely function as a primase processivity factor. Lef-2 genes have been found in multinucleocapsid nucleopolyhedroviruses (MNPVs) and in granuloviruses (GVs), but not yet in single-nucleocapsid NPV (SNPV). Here, a lef-2 gene homolog was identified from SNPV of Helicoverpa armigera (HearNPV). The open reading frame of the HearNPV lef-2 gene is 696 nucleotides long, encoding a putative protein of 232 amino acids with an M(r) of about 26 kDa. The 5'-noncoding region contains two early (CAGT) consensus motifs for transcription initiation and three TATA boxes. Lef-2 transcripts started at a C, 29 nucleotides upstream of a putative translational start. A putative polyA signal, AATAAA, was found 76 nucleotides downstream of the translation stop codon. The HearNPV lef-2 gene has a low but significant degree of amino acid sequence identity (30%) to the lef-2 genes of 15 other baculoviruses of which nine were newly determined. The N-terminal half of the LEF-2 proteins contains one (I) and the C-terminal half two (II and III) conserved domains. Sixteen amino acids are absolutely conserved in those LEF-2 investigated and are probably critical for LEF-2 function. A phylogenetic tree of 16 baculovirus LEF-2 proteins was constructed by using maximum parsimony analysis and appeared to be comparable to a tree for ecdysteroid UDP-glucosyl transferases (Chen et al., 1997a). The genomic location of the lef-2 genes relative to polyhedrin/granulin and the clade structure of the gene trees suggest that genome organization and gene phylogeny are useful parameters to study the evolutionary history of baculoviruses. These two independent approaches also give a more complete picture of the ancestral relationship among baculovirus.

Amino Acid Sequence↗

PubMed2002

Pivotal role of the beta-clamp in translesion DNA synthesis and mutagenesis in E. coli cells.

The genetic information is continuously subjected to the attack by endogenous and exogenous chemical and physical carcinogens that damage the DNA template, thus compromising its biochemical functions. Despite the multiple and efficient DNA repair systems that have evolved to cope with the large variety of damages, some lesions may persist and, as a consequence, interfere with DNA replication. By essence, the damaged-DNA replication process (hereafter termed translesion synthesis or TLS) is a major source of point mutations and is therefore deeply involved in the onset of human diseases such as cancer. Recent identification of numerous DNA polymerases involved in TLS has shed new light onto the molecular mechanisms of mutagenesis. Here, we show that in vivo, both error-free and mutagenic bypass activities of the three DNA polymerases known to be involved in TLS in Escherichia coli (PolII, PolIV and PolV) strictly depend upon the integrity of small peptidic sequences identified as their beta-clamp binding motif. Thus, in addition to its crucial role as the processivity factor of the PolIII replicase, the beta-clamp plays a pivotal role during the TLS process.

DNA Damage↗

PubMed1992

[Factors regulating growth processes in the ovary].

This paper summarizes the recent knowledge on the factors stimulating or inhibiting the ovarian growth. In the present review the following factors influencing growth processes in the ovary are discussed: gonadotropins, sex steroids, prolactin, renin, angiotensin II, atrial natriuretic factor (ANF), growth hormone, insulin, prostaglandins, pineal indoleamines, tissue growth factors and others. The role of nervous system is also described in the study. Not only gonadotropins and other stimulatory factors but also inhibitory agents, e.g., melatonin should be considered in the ovarian growth regulation. The hypertrophic and/or hyperplastic processes in the ovary seem to be dependent on either the excess of stimulatory agents or the deficit of the growth inhibitors.

Atrial Natriuretic Factor↗

PubMed2002

Interdisciplinary collaboration within Quebec Community Health Care Centres.

Central to the success of many recent health system reforms is the implementation of new primary health care delivery models. The central characteristic common to these new models usually emphasises interdisciplinary collaboration. Using empirical research, this paper studies interdisciplinary collaboration among various groups of professionals within an original Canadian primary health care delivery model, the Quebec Community Health Care Centres (CCHCs). The entire population of more than 150 CHCCs have been surveyed. The goals of this study are (1) to measure the achieved intensity of inter-professional collaboration among Quebec CHCCs, and (2) to identify the organisational and professional factors fostering or limiting interdisciplinary collaboration. The results show that Quebec CHCCs have reached modest results in achieving interdisciplinary collaboration especially since interdisciplinary collaboration is a central objective that has been pursued for more than 25 years. This study demonstrates that the main factors associated with interdisciplinary collaboration are closely linked to work group internal dynamics. Interdisciplinary collaboration is linked to the simultaneous and antagonistic effect of some central intragroup process factors. Conflicting values and beliefs are present that both enhance and limit interdisciplinary collaboration. The presence of conflicting stimuli seriously undermines the strength of the CHCC work group's shared beliefs and strongly limits interdisciplinary collaboration. The results also stress the importance of administrative formalisation initiatives to enhance collaboration among different professions. The efficacy of formalisation in this context is based on its capacity to offer an articulated and operative interdisciplinary framework that can generate a counteractive effect to the traditional professional framework. It offers concrete rules that help align the work group beliefs with interdisciplinary values. The formalisation of functions and processes appears thus to be an interesting means to further interdisciplinary collaboration.

Community Health Centers↗

PubMed2000

Process of conducting a 5-a-day intervention with high school students: Gimme 5 (Louisiana).

Gimme 5: A Fresh Nutrition Concept for Students (Gimme 5) was a 4-year intervention targeting increased fruit and vegetable consumption by high school students. Twelve schools were randomized to intervention or control conditions. The cohort (2,213 students; 56% female, 84% Euro-American) were followed from 9th to 12th grade. Interventions were composed of a school-based media campaign, classroom workshops, school meal modification, and parental involvement. For each of the four Gimme 5 intervention components, process evaluation measures were developed to assess program dose, penetration, and utilization, as well as external competing factors. Process evaluation results are presented to illustrate the various functions of process evaluation data. These include, but are not limited to, describing program implementation, quality control and monitoring, and explaining study outcomes. The implementation of process evaluation systems to complement the outcome measures in a high school-based intervention provides useful strategies for a more comprehensive approach to program evaluation.

Adolescent↗

PubMed2000

Primary care treatment of pediatric psychosocial problems: A study from pediatric research in office settings and ambulatory sentinel practice network.

OBJECTIVE: Psychosocial problems cause much of the morbidity among children, and their frequency of presentation in primary care is growing. How is primary care treatment of children's psychosocial problems affected by child symptoms, physician training, practice structure, insurance, physician/patient relationship, and family demographics? DESIGN: Questionnaire study of treatment of psychosocial problems during office visits by children. SETTINGS: At total of 401 primary care offices from 44 US states, Puerto Rico, and Canada. PATIENTS: From 21 150 children seen in office visits, we selected children with an identified psychosocial problem but who were not already receiving specialty mental health services (n = 2618 children). OUTCOME MEASURES: Clinicians' decisions to counsel families, to refer children to mental health specialists, or to prescribe medication. RESULTS: The treatment choices of primary care clinicians (PCCs) were generally independent of patients' demographics or insurance status. Clinicians' training, beliefs about mental health, and practice structure had no effect on treatment choices. However, clinicians seeing their own patients were more likely to prescribe medications for attention problems. The clinician's perception about whether the parent agreed with the treatment choice was important for every treatment modality. Counseling and referral were more common and medication was less common when a problem was newly recognized at the visit. CONCLUSIONS: Structural factors such as practice type, insurance coverage, and physician training were less important for treatment than were process factors, such as whether the visit was a psychosocial problem visit, whether the problem was newly or previously recognized, and whether the family and clinician were familiar with each other and in accord about treatment.

Adolescent↗

PubMed2003

Mechanism of corneal endothelial cells lesion during phacoemulsification and aspiration.

PURPOSE: To evaluate the proportions of corneal endothelial lesion caused by different factors during phacoemulsification and aspiration. METHODS: Fourteen cats (twenty eight eyes) were divided into four groups. The processed factors were ultrasonic power, lens extraction by phacoemulsification or not, and lens extraction using different levels of ultrasonic power. The density of central corneal endothelial cells was measured before and after operation. RESULTS: There is no statistic difference between pre-operation density and post-operation density for releasing ultrasonic power only without lens extraction group. But for the lens extraction group, there is difference in density of central corneal endothelial cells and the higher level of ultrasonic power, the more the central corneal endothelial cells density decreased through operation. CONCLUSION: The primary factor that causes corneal endothelial lesion during phacoemulsification and aspiration procedure is debris of lens nucleus, and the other factors cause the lesion of corneal endothelium in normal operations just in very small degree.

Animals↗

PubMed2001

Choreographing mRNA biogenesis.

Biogenesis of eukaryotic mRNA requires several post-transcriptional processing steps that must be completed accurately before it can be exported. Several processing factors are known to associate with RNA polymerase II during elongation, thereby positioning them to mediate efficient RNA processing. mRNAs are exported as complexes containing several RNA-binding proteins and other proteins. A recent study indicates that some of these packaging proteins also associate with RNA polymerase II during transcription. This suggests close coordination and mechanistic coupling of the events required to produce and export functional mRNAs.

Animals↗

PubMed2000

The ribosomal RNA processing machinery is recruited to the nucleolar domain before RNA polymerase I during Xenopus laevis development.

Transcription and splicing of messenger RNAs are temporally and spatially coordinated through the recruitment by RNA polymerase II of processing factors. We questioned whether RNA polymerase I plays a role in the recruitment of the ribosomal RNA (rRNA) processing machinery. During Xenopus laevis embryogenesis, recruitment of the rRNA processing machinery to the nucleolar domain occurs in two steps: two types of precursor structures called prenucleolar bodies (PNBs) form independently throughout the nucleoplasm; and components of PNBs I (fibrillarin, nucleolin, and the U3 and U8 small nucleolar RNAs) fuse to the nucleolar domain before components of PNBs II (B23/NO38). This fusion process is independent of RNA polymerase I activity, as shown by actinomycin D treatment of embryos and by the lack of detectable RNA polymerase I at ribosomal gene loci during fusion. Instead, this process is concomitant with the targeting of maternally derived pre-rRNAs to the nucleolar domain. Absence of fusion was correlated with absence of these pre-rRNAs in nuclei where RNA polymerase II and III are inhibited. Therefore, during X. laevis embryogenesis, the recruitment of the rRNA processing machinery to the nucleolar domain could be dependent on the presence of pre-rRNAs, but is independent of either zygotic RNA polymerase I transcription or the presence of RNA polymerase I itself.

Animals↗

PubMed1995

The Processes, Structures, and Outcomes of Care in Cardiac Surgery study protocol.

Recently, a growing interest has arisen in defining and measuring health care outcomes. Although outcome measures may be used as potential quality-of-care screens, outcomes cannot indicate directly how care might be improved. Thus, the Processes, Structures, and Outcomes of Care in Cardiac Surgery (PSOCS) study was designed to investigate the linkages between the processes and structures of care with risk-adjusted outcomes for cardiac surgery care. Data are being collected on a comprehensive array of risk factors, processes, structures, and outcomes of care at 14 Veterans Affairs Medical Centers for this prospective, observational study. Approximately 6,000 cardiac surgery patients will be enrolled in this study over a 4.5-year period. Patient selection is based on a 6 workday rotating sampling frame with an oversampling of emergent patients. During the study, a register of all patients undergoing cardiac surgery at these centers is being maintained to assess the overall context of patient recruitment. The study will continue to enroll patients through December 1996. Major study end points extend beyond traditional measures of 30-day mortality and morbidity to encompass more innovative intermediate outcome measures, including changes in physical functional status and health-related quality of life.

Aged↗