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J Curran

Publications and source records attributed to J Curran.

At least 37 records · Page 2Linked to original sources
PubMed1997

End-tidal carbon dioxide measurement and breathing system filters.

Breathing system filters are recommended for use during general anaesthesia. Manufacturers of gas sampling equipment recommend that gas is sampled from the 'machine side' of these filters, thereby avoiding contamination of the sampling line and waterlogging in the case of heat and moisture exchangers. The aim of this study was to investigate differences between the measured end-tidal carbon dioxide values at either side of the filter. Fifteen adults were studied during mechanical ventilation and 15 during spontaneous ventilation under general anaesthesia. End-tidal carbon dioxide values were significantly lower at the machine side of the filter in both groups (p = 0.00001). The measurement error induced by the inclusion of the breathing system filter was significantly greater in the spontaneously breathing group (p = 0.0004).

Adult↗
PubMed1997

Inhibition of Sendai virus genome replication due to promoter-increased selectivity: a possible role for the accessory C proteins.

The role of the negative-stranded virus accessory C proteins is difficult to assess because they appear sometimes as nonessential and thereby of no function. On the other hand, when a function is found, as in the case of Sendai virus, it represents an enigma, in that the C proteins inhibit replication under conditions where the infection follows an exponential course. Furthermore, this inhibitory function is exerted differentially: in contrast to the replication of internal deletion defective interfering (DI) RNAs, that of copy-back DI RNAs appears to escape inhibition, under certain experimental conditions (in vivo assay). In a reexamination of the C effect by the reverse genetics approach, it was found that copy-back RNA replication is inhibited by C in vivo as well, under conditions where the ratio of C to copy-back template is increased. This effect can be reversed by an increase in P but not L protein. The "rule of six" was differentially observed in the presence or absence of C. Finally, a difference in the ability of the replicating complex to tolerate promoter modifications in RNA synthesis initiation was shown to occur in the presence or the absence of C as well. We propose that C acts by increasing the selectivity of the replicating complex for the promoter cis-acting elements governing its activity. The inhibitory effect of C becomes the price to pay for this increased selectivity.

DNA-Directed RNA Polymerases↗
PubMed1996

Reexamination of the Sendai virus P protein domains required for RNA synthesis: a possible supplemental role for the P protein.

The Sendai virus P protein plays a central role in viral genome amplification and expression, forming complexes with the viral L protein to generate the polymerase (P-L) and unassembled N (P-N(o)). This latter complex prevents N from self-assembling illegitimately, i.e., independently of the concurrent assembly of a nascent viral genome, and is thought to represent the functional form of N in nucleocapsid assembly. Based upon earlier functional studies using an in vitro transcription/ replication system in which the P, L, and N proteins were coexpressed, we identified two regions of the P protein required for RNA synthesis, namely, the C-terminal 40% of the protein, and a second, apparently redundant domain near the N-terminus (either amino acids 1-77 or 78-145). The lack of sequence conservation in this second region, apart from overall negative charge, was reminiscent of the acidic activation domains of cellular transcription factors. However, we recently mapped a chaperone domain at the N-terminal of P (aa 33-41), which is required for stable complex formation with unassembled N(o) and, thus, for assembly and genome replication. In this present study we show that coexpression of N protein with P deletion mutants lacking this region (e.g., P delta 1-324) results in the sequestration of the mutant P by the illegitimately assembled form of N. As a consequence, P protein is unavailable for RNA synthesis from bona fide templates. We also find that in the absence of coexpressed N protein, the entire N-terminal 60% of the P protein is not required for mRNA synthesis. During these studies, a supplemental role for the P protein in viral RNA synthesis, independent of stable complex formation with L, was observed. This function involves, at least in part, the binding of additional copies of P to the N:RNA template.

Binding Sites↗
PubMed1996

Rescue of Sendai virus cDNA templates with cDNA clones expressing parainfluenza virus type 3 N, P and L proteins.

Several years ago, we reported that a Sendai virus (SeV) defective genome (DIH4UV) could be rescued in vivo with human parainfluenza virus type 1 (hPIV1) and bovine PIV3 but not by measles virus or vesicular stomatitis virus. It was concluded that the cis-acting RNA sequences were conserved within the SeV/PIV1/PIV3 group but that interactions between the polymerase complex (P-L) and the template protein N were unique for each virus. We have re-examined these conclusions using proteins expressed from cloned N, P and L genes for SeV and PIV3. The results demonstrate the specificity of the protein-protein interactions between polymerase and template, and confirm the prediction of the earlier work that PIV3 N, P and L proteins are capable of assembling and replicating SeV mini-genomes also expressed from a cDNA clone.

Animals↗
PubMed1996

Customization of a radiation management system to support in vivo patient dosimetry using diodes.

Considerable effort is generally made in the quality control of radiation therapy units and in patient chart checking to ensure accurate delivery of treatment to the patients. Record and verify (RV) systems have been implemented which will inhibit the beam from being turned ON if the parameters set on the medical linear accelerators do not match a preprogrammed file. It should be emphasized, however, that RV systems are designed only to ensure proper setup of parameters on the therapy units and bear no direct link with proper patient position. The only real link between treatment planning and delivery to the patient is in-vivo dosimetry. Diodes provide a convenient way of measuring the dose received by the patient in real time and, after the initial tedious calibrations, require very little additional effort. In order to facilitate diode use by the therapists in our institution, the radiation management system (RMS) database in use with our linear accelerators was interfaced with the output obtained from a commercially available diode dosimetry system. The chart printout format was altered to read this value from the RMS database allowing a near real-time recording of the actual dose received by the patient for up to three sites concurrently. This provides for an immediate additional check to the planned and received doses already recorded by the RMS RV software. This procedure, if carried out during the first treatment and subsequently on a weekly basis, would ensure that differences of the order of 5% or larger between planned and delivered dose would not go undetected.

Documentation↗
PubMed1996

The Sendai paramyxovirus accessory C proteins inhibit viral genome amplification in a promoter-specific fashion.

Many paramyxoviruses express small basic C proteins, from an alternate, overlapping open reading frame of the P gene mRNA, which were previously found to inhibit mRNA synthesis. During recent experiments in which infectious Sendai virus (SeV) was recovered from cDNA via the initial expression of the viral N, P, and L genes from plasmids, the abrogation of C protein expression from the plasmid P gene was found to be necessary for virus recovery. We have investigated the effect of C coexpression on the amplification of an internally deleted defective interfering (DI) genome directly in the transfected cell, for which, in contrast to virus recovery experiments, genome amplification is independent of mRNA synthesis carried out by the SeV polymerase. We find that C protein coexpression also strongly inhibits the amplification of this DI genome but has little or no effect on that of a copy-back DI genome (DI-H4). We have also characterized the C protein from a mutant SeV and found that (i) it had lost most of its inhibitory activity on internally deleted DI genome amplification and (ii) its coexpression no longer prevented the recovery of SeV from DNA. However, consistent with the insensitivity of copy-back DI genomes to C protein inhibition, C coexpression did not prevent the recovery of copy-back nondefective viruses from DNA. The inhibitory effects of C coexpression thus appear to be promoter specific.

Gene Amplification↗
PubMed1996

Orbit and optic nerve.

The optic nerve is a fiber tract of the brain, and is not a true cranial nerve. Primary pathologic processes seen in the central nervous system and its linings can therefore affect the optic nerve. Along their course the fibers of the visual pathways are also susceptible to secondary extrinsic processes. The MR appearance of many of the primary and secondary processes that affect the optic nerve are characteristic. Where the imaging features of a process are not characteristic, a fairly narrow differential diagnosis can be suggested depending on the imaging appearance and anatomic location of the pathologic entity. This article is a categorical overview of the disease entities that may affect the optic nerve and tracts. Pathologic processes are organized according to the typical sites of involvement along the visual pathways, from the retina to the occipital cortex. Medical imaging, pathologic, clinical, and epidemiological highlights are presented.

Brain Diseases↗
PubMed1995

A highly recombinogenic system for the recovery of infectious Sendai paramyxovirus from cDNA: generation of a novel copy-back nondefective interfering virus.

We have recovered infectious Sendai virus (SeV) from full-length cDNA (FL-3) by transfecting this cDNA and pGEM plasmids expressing the nucleocapsid protein (NP), phosphoprotein and large proteins into cells infected with a vaccinia virus which expresses T7 RNA polymerase. These cells were then injected into chicken eggs, in which SeV grows to very high titers. FL-3 was marked with a BglII site in the leader region and an NsiI site (ATGCAT) in the 5' nontranslated region of the NP gene, creating a new, out-of-frame, 5' proximal AUG. All the virus stocks generated eventually removed this impediment to NP expression, by either point mutation or recombination between FL-3 and pGEM-NP. The recovery system was found to be highly recombinogenic. Even in the absence of selective pressure, one in 20 of the recombinant SeV generated had exchanged the NP gene of FL-3 with that of pGEM-NP. When a fifth plasmid containing a new genomic 3' end without the presumably deleterious BglII site was included as another target for recombination, the new genomic 3' end was found in the recombinant SeV in 12 out of 12 recoveries. Using this approach, a novel copy-back nondefective virus was generated which interferes with wild-type virus replication.

Animals↗
PubMed1995

Paramyxovirus phosphoproteins form homotrimers as determined by an epitope dilution assay, via predicted coiled coils.

When HA epitope-tagged and untagged Sendai virus (SeV) P proteins are coexpressed and the products reacted with anti-HA, the untagged P protein is also selected because this protein is found as an oligomer. The oligomer was determined to be a homotrimer by coselection studies in which increasing amounts of untagged versus tagged protein were coexpressed, and these findings were extended to mumps virus, a member of the rubulavirus genus. The region of the SeV protein responsible for the oligomerization was localized to residues 344-411. Computer analysis of the 13 Paramyxovirus P proteins in the database revealed that all but one are predicted to form coiled coils in this region, the first of only two regions that can be aligned throughout the entire virus subfamily. The predicted coiled-coil region of the measles virus P protein, when grafted onto the C-terminus of the normally monomeric La protein, led to the efficient oligomerization of this reporter protein. The predicted coiled-coil region of these P proteins thus appears to be sufficient for oligomerization.

Amino Acid Sequence↗
PubMed1995

An N-terminal domain of the Sendai paramyxovirus P protein acts as a chaperone for the NP protein during the nascent chain assembly step of genome replication.

Two domains involved in RNA synthesis have recently been found within the N-terminal 77 amino acids of the Sendai virus P protein. One domain is required for RNA synthesis per se and has properties in common with the transactivation domains of cellular transcription factors. The second domain is thought to be specifically required for the nascent chain assembly step in genome replication. We have further mapped this second domain by the construction of chimeric and deleted P proteins to amino acids 33 to 41 of P and by examining the abilities of these P proteins to support DI genome replication in vivo. Using glycerol gradient sedimentation, we have shown that this domain is required to form a stable complex with unassembled NP (P-NP0) and to prevent NP from assembling illegitimately, i.e., independently of the concurrent assembly of a nascent viral genome. Since the P-NP0 complex represents the functional form of unassembled NP which is delivered to the nascent chain during genome replication, and since amino acids 33 to 41 are not required for the stable interaction of P with the assembled NP of the nucleocapsid, this chaperone function of P is not required for mRNA synthesis or the RNA synthesis step of genome replication.

Amino Acid Sequence↗
PubMed1994

An acidic activation-like domain of the Sendai virus P protein is required for RNA synthesis and encapsidation.

The Sendai virus polymerase is composed of the P and L proteins and carries out both mRNA synthesis and genome replication from the same nucleocapsid template. For mRNA synthesis, P interacts with the assembled NP of the nucleocapsid, and for genome replication, P interacts as well with unassembled NP for nascent chain assembly. The V and W nonstructural proteins, which are translated from edited P gene mRNAs and contain only the N-terminal half of the P protein, were found to inhibit genome replication but not mRNA synthesis. As genome replication is thought of as RNA synthesis plus concurrent encapsidation of the nascent chain, this half of P presumably plays a specific role in RNA encapsidation. Deletion analysis of the P gene found that residues 1-77 in the N-terminal half were in fact essential for RNA encapsidation. Moreover, either residues 1-77 or 78-144 also provided a function that was essential for RNA synthesis per se. Unlike other regions of P, such as those which bind NP in the C-terminal half, the N-terminal domains are very poorly conserved even among related viruses, show signs of acting in a position-independent manner, and, at least for RNA synthesis, are functionally redundant, similar to acidic activation domains of cellular transcription factors.

DNA-Directed RNA Polymerases↗
PubMed1994

Presence of a truncated form of the Sendai virus P protein in a long-term persistent infection: implications for the maintenance of the persistent state.

In this report we have monitored viral gene expression, both at the RNA and protein level, after the establishment of a long-term persistent infection of Sendai virus. The persistent infection was initially established by infecting BHK cells with a viral stock containing a short (1.4 kb) copy-back DI (DIH4). After over 120 weeks in culture this short copy-back DI had been replaced by two large deletion DIs (approximately 7 and 12 kb) from which was expressed an N-terminally truncated form of the P protein. The mRNA for this protein was detected in cells and the deletion within the P gene was mapped by PCR cloning and sequencing of intracellular nucleocapsid RNA. This truncated P protein (derived by deleting the N-terminal half of the cloned Pwt gene) has already been shown to function as a dominant negative for DI replication when driven by cloned viral genes. Cloning and expression of the truncated P from the long-term persistent infection revealed that this protein had retained the dominant negative phenotype. The presence of such a protein would severely depress viral gene expression and may therefore play an important role in the maintenance of persistence.

Animals↗
PubMed1994

Effects of passive and active smoking on induction of anaesthesia.

It is said that cigarette smokers suffer stormy induction of anaesthesia; although plausible, this is unsubstantiated. We have studied the incidence of adverse events during induction, together with peripheral oxygen saturation (SpO2), in active and passive smokers, and in non-smokers. During induction, both active and passive smokers had a higher incidence of adverse events than non-smokers (P < 0.01 and P < 0.05, respectively). Irrespective of smoking status, those suffering adverse events had greater concentrations of carboxyhaemoglobin and suffered more oxygen desaturation than those not suffering such events. Although we were unable to demonstrate a direct link between smoking status and oxygen desaturation during induction, our study gives a firmer basis for exhorting patients not only to stop smoking before anaesthesia but also to avoid passive smoking.

Adolescent↗
PubMed1994

A five year review of fatal self-ingested overdoses involving amitriptyline in Edinburgh 1983-'87.

One hundred and twelve cases of fatal self-ingested overdoses were investigated in the Forensic Medicine Unit of the Department of Pathology of the University of Edinburgh in the period 1983-'87 (inclusive). Of these, 24 cases involved amitriptyline as either the sole agent or in combination with another drug, the most common of which was ethanol. The mean age of the latter group was 43 years with a marked female preponderance. The social history was documented with six out of the 24 cases living alone and five out of the 24 cases divorced. The number previously referred for psychiatric treatment and the number of cases where over 100 tablets of the drug had been prescribed at any one time (where known) was recorded: eight out of 24 cases. The fact that amitriptyline was by far the commonest of the tricyclic antidepressants to be encountered in a fatal overdose situation raises the important question of the prescribing of amitriptyline as a first line therapy in mental depression.

Adolescent↗
PubMed1994

Clinical and MR correlates in children with extrapyramidal cerebral palsy.

PURPOSE: To identify the characteristic MR findings in extrapyramidal cerebral palsy. METHOD: Six patients who had suffered intrapartum asphyxia and who subsequently developed extrapyramidal cerebral palsy were identified. Asphyxia was evidenced by severe neonatal systemic acidosis as documented by a venous cord pH of less than 7.0 whenever available, or acidosis in subsequent arterial blood gas samples, and clinical signs of an acute hypoxic-ischemic encephalopathy during the neonatal period. In addition, 1- and 5-minute Apgar scores were 3 or less, and there had been need for intubation or vigorous resuscitation in the delivery room. There were three boys and three girls, all born at term, with birth weight appropriate for gestational age, and without a history of bilirubin levels above 15 mg/dL. MR imaging at 1.5 T was performed between 1 and 19 years of age. RESULTS: In all subjects focal high signal abnormality was demonstrated in the posterior putamen and the anterior or posterior thalamus. There were no other findings in most cases. CONCLUSION: MR demonstrated lesions in the putamen and thalamus in all of our six patients with severe extrapyramidal cerebral palsy who had suffered intrapartum asphyxia.

Adolescent↗
PubMed1993

The hypervariable C-terminal tail of the Sendai paramyxovirus nucleocapsid protein is required for template function but not for RNA encapsidation.

The paramyxovirus nucleocapsid proteins (NPs) are relatively well conserved, except for the C-terminal 20% (or ca. 100 amino acids), referred to as the tail. We have examined whether this hypervariable tail is required for genome synthesis, both in vitro, where synthesis is predominantly from the input templates, and in vivo, where multiple rounds of amplification occur. In these viruses, genome synthesis and assembly of the nascent chain are coupled. We find that the tail is required in vivo but not in vitro. Closer examination of the in vivo system showed that the tailless NP could encapsidate the genome chain but that amplification did not occur. We interpret these results as indicating that the tail is not required for RNA assembly but is required for the template to function in RNA synthesis. Relatively small deletions within the conserved N-terminal 80% of the protein, on the other hand, rendered the protein nonfunctional in either system. The possible functions of the tail in RNA synthesis are discussed.

Amino Acid Sequence↗
PubMed1992

Molecular cloning of natural paramyxovirus copy-back defective interfering RNAs and their expression from DNA.

Using the unique sequence organization of copy-back defective interfering (DI) RNAs of paramyxoviruses, Sendai virus (SV), and measles virus copy-back DI RNAs were PCR amplified and cloned, without having to separate them from their helper nondefective genomes. The cloning was designed so that T7 polymerase transcription of the plasmids would generate DI RNAs with the exact 5' and 3' ends. The SV DI clone, transcribed from the plasmid in BHK cells using T7 polymerase produced by a vaccinia virus recombinant, was encapsidated and replicated by the SV-L, P/C, and NP proteins expressed from cloned genes. Such experiments open the possibility of examining the cis-acting sequences involved in viral multiplication directly, without using indirect markers such as CAT activity.

Animals↗