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Biomedical subjects

J R Murray

Publications and source records attributed to J R Murray.

At least 19 recordsLinked to original sources
PubMed2005

Radiation-driven hydrodynamics of high- hohlraums on the national ignition facility.

The first hohlraum experiments on the National Ignition Facility (NIF) using the initial four laser beams tested radiation temperature limits imposed by plasma filling. For a variety of hohlraum sizes and pulse lengths, the measured x-ray flux shows signatures of filling that coincide with hard x-ray emission from plasma streaming out of the hohlraum. These observations agree with hydrodynamic simulations and with an analytical model that includes hydrodynamic and coronal radiative losses. The modeling predicts radiation temperature limits with full NIF (1.8 MJ), greater, and of longer duration than required for ignition hohlraums.

Journal Article↗
PubMed2005

Implications for prediction and hazard assessment from the 2004 Parkfield earthquake.

Obtaining high-quality measurements close to a large earthquake is not easy: one has to be in the right place at the right time with the right instruments. Such a convergence happened, for the first time, when the 28 September 2004 Parkfield, California, earthquake occurred on the San Andreas fault in the middle of a dense network of instruments designed to record it. The resulting data reveal aspects of the earthquake process never before seen. Here we show what these data, when combined with data from earlier Parkfield earthquakes, tell us about earthquake physics and earthquake prediction. The 2004 Parkfield earthquake, with its lack of obvious precursors, demonstrates that reliable short-term earthquake prediction still is not achievable. To reduce the societal impact of earthquakes now, we should focus on developing the next generation of models that can provide better predictions of the strength and location of damaging ground shaking.

Journal Article↗
PubMed2004

Are we training junior doctors to respond to major incidents? A survey of doctors in the Wessex region.

OBJECTIVE: To assess the current status of awareness and training of junior medical staff in the Wessex region in the event of a "conventional" major incident. METHODS: A telephone questionnaire of specialist registrars (SpRs) (or equivalent, for example, staff grade) in six core specialties was performed in all the 11 acute hospitals in the Wessex region on the same evening. This group was selected to represent a sample of the most senior medical staff "on site" at each hospital. RESULTS: 56 of 64 (87.5%) SpRs participated. Nine of the 56 (16%) SpRs questioned had previously been involved in a major incident, and 18 (32%) had experienced some form of major incident training exercise. Subgroup analysis of the specialties showed that although there were no significant differences in numbers of training experiences between specialties, only one of nine (11%) orthopaedic SpRs had ever been involved in a training exercise. Twenty five of the 56 (45%) SpRs felt that they were confident of their role in the event of an incident. CONCLUSION: Most middle grade staff in Wessex were not confident of their role in the event of a major incident. Most SpRs questioned had never attended a major incident training exercise.

Attitude of Health Personnel↗
PubMed1996

Anesthetic management and outcome following noncardiac surgery in nonparturients with Eisenmenger's physiology.

STUDY OBJECTIVE: To evaluate the perioperative risk to nonparturients with Eisenmenger's physiology for noncardiac surgical procedures. DESIGN: Retrospective chart review. SETTING: University-affiliated hospital. PATIENTS: 12 nonparturients with Eisenmenger's physiology who underwent 25 noncardiac surgical procedures requiring care by an anesthesiologist. MEASUREMENTS AND MAIN RESULTS: Preoperative, intraoperative, and postoperative records were retrospectively analyzed. Data examined included patient age, gender, symptoms, laboratory values, monitors used, surgical procedure, and outcome. Twenty-five procedures were performed on 12 patients; 13 procedures were performed with general anesthesia, 6 with peripheral nerve blocks, 5 with sedation by an anesthesiologist with or without local anesthetic infiltration, and one with epidural anesthesia. One patient died perioperatively. Review of the literature revealed two deaths in 32 procedures for nonparturients with Eisenmenger's physiology undergoing noncardiac surgery. CONCLUSIONS: A variety of anesthetic techniques and drugs may be used successfully in nonparturients with Eisenmenger's physiology undergoing noncardiac surgery. Although the study group is small, the perioperative mortality risk is lower than that for parturients undergoing either labor and delivery or cesarean section and is probably in the range of approximately 10%.

Adolescent↗
PubMed1994

Annual managed care systems review. Behold the beast.

Remember the story of the three blind men, each confronted by a different part of an elephant? Asked to describe the object in front of them, they each described the part they could touch. In his quest to survey more than 100 managed care systems vendors, author John R. Murray discovered that defining managed care is very much like describing an elephant without seeing the entire beast: Each company's definition is based on its niche and product offering to the market.

Ambulatory Care Information Systems↗
PubMed1991

Effects of an experimental contact lens disinfectant on rabbit corneal epithelium cultures.

We investigated the toxicity of a new, chlorine-based, experimental contact lens disinfectant (Alcide Corp., Norwalk, CT) on rabbit corneal epithelium in tissue culture. Explants of isolated corneal epithelium were grown in tissue culture for 7 days and then exposed for 1 h to one of three different concentrations of the experimental disinfectant or to a saline control. At the manufacturer's standard concentration, and at one-half the standard concentration, the relative area covered by living cells in the culture was reduced an average of 32% 3 days after treatment. At double the standard concentration, the area was reduced 63%, which was a significant reduction in comparison with controls. All groups showed some recovery in area of living epithelial cells within 7 days after treatment. In comparison with similar studies on other chemicals used in ophthalmic preparations, these results suggest that this chlorine-based disinfectant is relatively nontoxic to corneal epithelial cells.

Analysis of Variance↗
PubMed1991

Dihydroflavonol Reductase Activity in Relation to Differential Anthocyanin Accumulation in Juvenile and Mature Phase Hedera helix L.

Juvenile phase English ivy (Hedera helix L.) plants accumulate anthocyanin pigment in the hypodermis of stems and petioles, whereas genetically identical plants of the mature phase do not. The objective of this work was to assess which enzyme(s) might limit anthocyanin accumulation in mature phase ivy. Leaf discs of both juvenile and mature phase ivy accumulated comparable levels of the flavonols kaempferol and quercetin, whereas only juvenile phase discs accumulated anthocyanin. The accumulation of quercetin, but lack of accumulation of leucocyanidin or anthocyanin in mature phase discs, suggested that mature discs lacked dihydroflavonol reductase activity. There was no detectable dihydroflavonol reductase activity in mature phase discs, whereas there was an induction of activity in juvenile phase discs in response to sucrose, or photosynthetically fixed carbon, and light as a photomorphogenic signal. Phenylalanine ammonia-lyase, an enzyme early in the anthocyanin biosynthetic pathway, was induced above its basal level by sucrose and light in discs of both phases of ivy, with greater activity in mature phase discs. Phenylpropanoids, a class of compounds that are precursors to flavonoids, accumulated in leaf discs of both phases, with greater levels in mature phase discs. These results indicate that the lack of dihydroflavonol reductase activity limits the accumulation of anthocyanin in mature phase tissue.

Journal Article↗
PubMed1990

Clinical and subclinical Barmah Forest virus infection in Queensland.

Barmah Forest virus is a mosquito-borne agent (alphavirus) reported to cause both clinical and subclinical infections in New South Wales. This report describes 29 cases of clinical Barmah Forest virus infection diagnosed between July 1988 and March 1989 (21 from Queensland, six from New South Wales and two from Victoria) and provides evidence of extensive subclinical infection with this virus (0.23% of the population per annum) throughout Queensland. It also includes a description of the first isolation of Barmah Forest virus from a patient. Data obtained in the course of the study suggest that Barmah Forest virus infections may not be diagnosed correctly in many instances because of the similarity of the symptoms of this disease to those of epidemic polyarthritis and the small number of laboratories providing the necessary serological services.

Adolescent↗
PubMed1989

The history of corticosteroids.

The development from the discovery of the structure of cholesterol, the precursor of all steroids, to the first application of a topically effective steroid in 1952 took about 20 years. Thereafter the development of more potent topically effective steroids accelerated and the third generation of potent steroids with a topical activity of about 10 to 20 times that of hydrocortisone was already available about 10 years later. Today the newly developed non-fluorinated non-symmetric 16 alpha, 17 alpha-acetal derivate budesonide could perhaps be considered as the sixth generation.

Adrenal Cortex Hormones↗