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Biomedical subjects

R M Cooper

Publications and source records attributed to R M Cooper.

At least 19 recordsLinked to original sources
PubMed2001

Changes in (14)C-labeled 2-deoxyglucose brain uptake from nickel-induced epileptic activity.

Unilateral epidural applications of nickel solution to motor cortex were followed in about 1 h by contralateral forelimb myoclonus. In rats which displayed frequent myoclonal jerking during the 45-min 2-deoxyglucose (2-DG) uptake and clearing period, autoradiographic analysis showed that glucose utilization at the nickel implant site was greater in the supragranular and infragranular layers than in the granular layer (in normal cortex, activity is greatest in the granular layer), and was also greater in the substantia nigra and other subcortical centers. The same cortical and most of the subcortical changes in 2-DG uptake were also observed when metabolic activity was assessed 1 h after myoclonus had stopped, indicating that it may not have been the seizure activity itself that had altered metabolic activity, but some process engendered by the seizures - possibly a tissue response to excitotoxic damage. In fact, rats which displayed infrequent myoclonus showed negligible increases in cortical and subcortical uptake. These results do not support an earlier claim that increased glucose consumption is the metabolic signature of the interictal activity produced by seizure-inducing metals. Indeed, the findings raise the possibility that tissue damage is responsible for interictal hypermetabolism when it is observed in animal models of epilepsy.

Animals↗
PubMed2000

Characterization of SNP1, a cell wall-degrading trypsin, produced during infection by Stagonospora nodorum.

Stagonospora (= Septoria) nodorum when grown in liquid culture with wheat cell walls as the sole carbon and nitrogen source secretes numerous extracellular depolymerases, including a rapidly produced, alkaline, trypsin-like protease (SNP1). The enzyme was purified 417-fold by cation exchange chromatography and has a molecular mass of 25 kDa on sodium dodecyl sulfate gels, pI 8.7, and pH optimum of 8.5. It cleaved peptide bonds on the carboxyl side of lysine or arginine, was strongly inhibited by the trypsin inhibitors aprotinin and leupeptin and weakly by phenylmethylsulfonyl fluoride, and its activity was stimulated by calcium. SNP1 has the characteristic, conserved, fungal, trypsin N terminus. Polymerase chain reaction (PCR) primers based on this sequence and the conserved trypsin active site were used to amplify a DNA fragment that facilitated isolation of the corresponding genomic clone from a lambda library of S. nodorum. The full-length sequence confirmed its identity as a trypsin-like protease containing the N-terminal sequence of the previously purified enzyme. Infected leaf tissue contained a protease, not present in controls, that coeluted with the fungal trypsin from cation exchange, and had properties (pI and inhibitor characteristics) similar to those of the fungal trypsin. SNP1 expression in planta was detected by Northern (RNA) blotting, reverse transcription PCR, and green fluorescent protein confocal microscopy. SNP1 released hydroxyproline from wheat cell walls. The release of hydroxyproline, together with its early expression in planta, suggests that SNP1 participates in the degradation of host cell walls during infection.

Amino Acid Sequence↗
PubMed1999

Improved expression in hematopoietic and lymphoid cells in mice after transplantation of bone marrow transduced with a modified retroviral vector.

Retroviral vectors based on the Moloney murine leukemia virus (MoMuLV) are currently the most commonly used vehicles for stable gene transfer into mammalian hematopoietic cells. But, even with reasonable transduction efficiency, expression only occurs in a low percentage of transduced cells and decreases to undetectable levels over time. We have previously reported the modified MND LTR (myeloproliferative sarcoma virus enhancer, negative control region deleted, dl587rev primer-binding site substituted) to show increased expression frequency and decreased methylation in transduced murine embryonic stem cells and hematopoietic stem cells. We have now compared expression of the enhanced green fluorescent protein (eGFP) from a vector using the MoMuLV LTR (LeGFPSN) with that from the modified vector (MNDeGFPSN) in mature hematopoietic and lymphoid cells in the mouse bone marrow transplant (BMT) model. In primary BMT recipients, we observed a higher frequency of expression from the MND LTR (20% to 80%) in hematopoietic cells of all lineages in spleen, bone marrow, thymus, and blood compared with expression from the MoMuLV LTR (5% to 10%). Expression from the MND LTR reached 88% in thymic T lymphocytes and 54% in splenic B lymphocytes for up to 8 months after BMT. The mean fluorescence intensity of the individual cells, indicating the amount of protein synthesized, was 6- to 10-fold higher in cells expressing MNDeGFPSN compared with cells expressing LeGFPSN. Transduction efficiencies determined by DNA polymerase chain reaction of vector copy number were comparable for the 2 vectors. Therefore, the MND vector offers an improved vehicle for reliable gene expression in hematopoietic cells.

3T3 Cells↗
PubMed1998

The unanticipated difficult airway with recommendations for management.

PURPOSE: To review the current literature and generate recommendations on the role of newer technology in the management of the unanticipated difficult airway. METHODS: A literature search using key words and filters of English language and English abstracted publications from 1990-96 contained in the Medline, Current Contents and Biological Abstracts databases was carried out. The literature was reviewed and condensed and a series of evidence-based recommendations were evolved. CONCLUSIONS: The unanticipated difficult airway occurs with a low but consistent incidence in anaesthesia practice. Difficult direct laryngoscopy occurs in 1.5-8.5% of general anaesthetics and difficult intubation occurs with a similar incidence. Failed intubation occurs in 0.13-0.3% general anaesthetics. Current techniques for predicting difficulty with laryngoscopy and intubation are sensitive, non-specific and have a low positive predictive value. Assessment techniques which utilize multiple characteristics to derive a risk factor tend to be more accurate predictors. Devices such as the laryngeal mask, lighted stylet and rigid fibreoptic laryngoscopes, in the setting of unanticipated difficult airway, are effective in establishing a patient airway, may reduce morbidity and are occasionally lifesaving. Evidence supports their use in this setting as either alternatives to facemask and bag ventilation, when it is inadequate to support oxygenation, or to the direct laryngoscope, when tracheal intubation has failed. Specifically, the laryngeal mask and Combitube have proved to be effective in establishing and maintaining a patent airway in "cannot ventilate" situations. The lighted stylet and Bullard (rigid) fibreoptic scope are effective in many instances where the direct laryngoscope has failed to facilitate tracheal intubation. The data also support integration of these devices into strategies to manage difficult airway as the new standard of care. Training programmes should ensure graduate physicians are trained in the use of these alternatives. Continuing medical education courses should allow physicians in practice the opportunity to train with these alternative devices.

Education, Medical, Continuing↗
PubMed1998

Use and safety of percutaneous tracheostomy in intensive care. Report of a postal survey of ICU practice.

A brief questionnaire was sent to 231 clinical directors of intensive care units in England and Wales to investigate the use of percutaneous tracheostomy. There was a 76% response rate. Percutaneous tracheostomies were in use in 78.4% of units. The Ciaglia technique was the most commonly used, with 31.3% routinely using fibreoscopy as part of their technique. Only 12% of units routinely provided long-term follow up of their percutaneous tracheostomies. Overall, 78.4% thought that percutaneous tracheostomy was safe and 66.7% considered percutaneous tracheostomy to be the technique of choice for Intensive Care patients. Percutaneous tracheostomy is now a well-established technique. However, the limited use of fibreoscopy and the lack of long-term follow-up are areas of concern.

Attitude of Health Personnel↗
PubMed1998

Propofol anesthesia, seizure duration, and ECT: a case report and literature review.

Propofol is a nonbarbiturate anesthetic induction agent known to have anti-convulsant properties. When used as an anesthetic for electroconvulsive therapy (ECT), it can reduce seizure duration to a significant degree, which may not be fully appreciated. A case is presented in which propofol caused a 63.1% reduction in mean seizure duration compared with preceding and subsequent treatments with thiopental anesthesia. The literature on the use of propofol for ECT was reviewed with specific reference to its effect on seizure duration and any evidence of superiority to the barbiturate induction agents. It is concluded that propofol may have only very circumscribed indications as an anesthetic for ECT. If used, psychiatrists and anesthetists must be aware of its potency as an anticonvulsant.

Adult↗
PubMed1997

Effects of neocortical implants of cobalt and other seizure-inducing metals on brain C-14 2-deoxyglucose uptake.

Nine days after insertion of a pure cobalt metal rod into the visual cortex, regions of increased 2-DG uptake are observed both in relatively normal Nissl-staining tissue lying around the implant site and in the connecting dorsal lateral geniculate nucleus of the thalamus. These hypermetabolic regions have been claimed to be the metabolic 'signatures' of tissue made epileptogenic by the cobalt. The present study showed, however, that while the 'dark patches' develop following posterior cortex implants, they do not appear after anterior cortex cobalt implants. Moreover, the dark patches were not detectable after cortical implants of other seizure-inducing metals such as antimony and nickel. These new findings indicate that the dark patches occur too idiosyncratically to make them the metabolic 'signatures' of tissue made epileptic by cobalt.

Animals↗
PubMed1996

The use of an endotracheal ventilation catheter in the management of difficult extubations.

PURPOSE: To describe the clinical experience with a new device, designed to maintain airway access following tracheal extubation. FEATURES: The endotracheal ventilation catheter (ETVC) is a semi-rigid polyurethane catheter with a distal hole and side-holes. A proximal connector permits attachment to a high pressure gas source for jet ventilation. Such a device can be introduced through an existing endotracheal tube, prior to its removal, and then used as stylet to facilitate reintubation. In 202 consecutive patients, the main use was to maintain airway access for up to 72 hr. It was well tolerated and associated with a high probability of successful reintubation even when the glottis cannot be visualised. CONCLUSION: The ETVC is a safe and effective means of maintaining airway access after tracheal extubation, even when the glottis cannot be visualized.

Catheterization↗
PubMed1996

Mothers' knowledge of the risk factors and anxiety about SIDS.

OBJECTIVE: To assess the impact on mothers' knowledge and anxiety of the 1991-92 health promotion campaign on Sudden Infant Death Syndrome (SIDS) risk factors. METHODOLOGY: A telephone survey of a population based sample of 339 mothers in Victoria, Australia, conducted 1992-94. RESULTS: Recall by mothers of the risk factors for SIDS was as follows: not breast-feeding, 15%; smoking, 46%; overheating, 48%; and prone sleeping, 84%. Recall rate increased as the campaign progressed. Receiving the campaign pamphlet was associated with an increased recall of all risk factors. Discussion of the pamphlet with a health professional was rare (9%). One-third of all mothers reported being very worried about cot death when caring for their babies. Self-reported worry was significantly more common among mothers whose babies were born at the time of the campaign introduction. CONCLUSIONS: The campaign pamphlets were effective in increasing knowledge of the risk factors. The limited discussion with health professionals suggests that future campaigns need increased professional involvement to address problems, including anxiety among new mothers.

Anxiety↗
PubMed1996

A combined cobalt and C-14 2-deoxyglucose approach to antiepileptic drug assessment.

The cobalt model of epilepsy, in combination with the C-14 2-deoxyglucose (2-DG) autoradiographic technique, was used to assess the effects of phenytoin (PHT) and ethosuximide (ESM), two antiepileptic drugs, and ketamine (KET), a drug with anticonvulsant properties, on brain activity. Nine days after the unilateral insertion of a cobalt rod into visual cortex, the nondrugged control rats showed the usual hypermetabolic regions of putative epileptogenic tissue both adjacent to the necrotic cortical cobalt rod implant zone and more distally in the connecting thalamus. PHT and ESM, given a single injections immediately before the 2-DG uptake and clearing period, diminished glucose uptake in the cobalt-induced hypermetabolic "patches" as well as in normal tissue. However, both drugs decreased 2-DG uptake more in the thalamic patches, than in the less hypermetabolic cortical patches, where the drug-induced depression in glucose metabolism was the same as for normal tissue. These findings suggest that PHT and ESM, regardless of their actions on cell receptors and membrane conductances, are ultimately of therapeutic value because more active nervous tissue (such as epileptic tissue) is more vulnerable to the depressing effects of these drugs than is less active tissue. KET, in contrast to PHT and ESM, did not depress metabolic activity throughout the brain generally and even clearly increased it in limbic system structures. Also in contrast to PHT and SEM, KET diminished activity in the cobalt-induced patches without reducing it in the normal tissue of the homotopic control regions. The more selective depressing action of KET, an N-methyl-D-aspartate (NMDA) antagonist, may be related to the role NMDA receptors play in supporting strong nervous activity. The discussion emphasizes the usefulness of a combined cobalt/2-DG approach to antiepileptic drug assessment.

Animals↗
PubMed1995

Cloning and characterisation of a gene encoding a cuticle-degrading protease from the insect pathogenic fungus Metarhizium anisopliae.

Metarhizium anisophilae (Ma) secretes a range of proteases when grown in vitro on insect cuticle. A trypsin-like serine protease, PR2, was purified from culture filtrates by anion exchange chromatography and the N-terminal sequence determined. Using oligodeoxyribonucleotide probes based on this sequence and that of the highly conserved trypsin active site, a gene was isolated from a lambda EMBL3 genomic library of Ma isolate ME1. Sequencing of the gene and RT-PCR revealed that the gene contains two introns which are 94 and 40 bp long. The deduced protein consists of 254 amino acids, has a putative signal sequence to allow transport into the endoplasmic reticulum and probably undergoes a second proteolytic processing step at its N terminus to yield the mature enzyme. The putative mature enzyme has extensive homology with other serine proteases of the trypsin subclass and, in particular, with the trypsin characterised from Fusarium oxysporum.

Amino Acid Sequence↗
PubMed1995

Superiority of conventional culture technique over rapid detection of group A Streptococcus by optical immunoassay.

An optical immunoassay (OIA) has been reported to be more sensitive than conventional culture for the detection of Group A Streptococcus, eliminating the need for culture. We attempted to confirm the sensitivity and specificity through a laboratory quantitation study and a clinical trial. OIA did not detect Group A Streptococcus below 10(5) colony forming units (CFU). Culture detected Streptococcus to 10(2) CFU from the inoculated swab. In the clinical study, throat swabs were obtained from 77 patients in an outpatient clinic. Compared with culture, the sensitivity of OIA was 78% and the specificity was 90%. These results demonstrate that OIA was less sensitive than culture in seeded experiments and missed 22% of positives in clinical practice. Our study, contrary to previous reports, suggests that OIA is not sensitive enough to be used as the sole assay for Group A Streptococcus pharyngitis.

Adult↗