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Biomedical subjects

D Morley

Publications and source records attributed to D Morley.

At least 19 recordsLinked to original sources
PubMed2001

Growth monitoring.

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Anthropometry↗
PubMed2001

Turbine blood pumps.

After years of development and preclinical testing, clinical trials of the MicroMed DeBakey VAD began in November 1998 in Europe and in June 2000 in the United States. As of August 2000, 44 patients in Europe and 3 patients in the United States have undergone implantation with the MicroMed DeBakey VAD. In conclusion, data from the European clinical trial of the MicroMed DeBakey VAD support the safety and performance of the device. Results show that the device provides adequate left ventricular and circulatory support in patients with end-stage heart failure without unduly jeopardizing patient safety. Moreover, the device provides advantages not inherent to commercially available pulsatile devices: (1) miniature size, enabling implantation in smaller patients; (2) ease of implantation; (3) reduced surgical bleeding; and (4) a low incidence of postoperative infections, often a limiting factor with other devices. The MicroMed DeBakey VAD European clinical trial is the first demonstration of the compatibility of continuous blood flow with adequate tissue perfusion and overall maintenance of life for up to 4.5 months. This initial experience with the MicroMed DeBakey VAD suggests that the pump can provide circulatory support to bridge patients to cardiac transplantation and may provide an improved quality of life for the patient with end-stage heart failure.

Animals↗
PubMed2000

A new method for the selection of protein interactions in mammalian cells.

In the present study we present a new method that allows for the selection of protein interactions in mammalian cells. We have used this system to verify two interactions previously characterized in vitro. (1) The interaction between human TATA-binding protein 1 and nuclear factor kappaB and (2) the association of Homo sapiens nuclear autoantigen SP100B with human heterochromatin protein 1alpha, a protein implicated in chromatin remodelling. We observe for the first time that these interactions also occur in vivo. One protein was fused to the N-terminal half of ubiquitin, while the interacting partner was fused to the C-terminal half of ubiquitin, that was itself linked to guanine phosphoryltransferase 2 (gpt2) modified to begin with an arginine residue. Upon interaction of both proteins, ubiquitin is reconstituted, and its association with the Rgpt2 reporter is subsequently cleaved off by ubiquitin-processing enzymes. The presence of arginine in the Rgpt2 gene product leads to the degradation of the product by the N-end rule pathway. In the human fibroblast cell line HT1080HPRT(-) (that is deficient in the enzyme for hypoxanthine-guanine phosphoribosyltransferase) cells in which interaction between both proteins of interest occurs can then be selected for by hypoxanthine/aminopterin/thymine medium and counterselected against by 6-thioguanine medium. This method provides a suitable alternative to the yeast two-hybrid system and is generally applicable.

Antigens, Nuclear↗
PubMed2000

Development and clinical application of the MicroMed DeBakey VAD.

A miniaturized axial flow pump to provide left ventricular assistance has been developed. Such a device has the potential to address limitations of the larger pulsatile devices. Clinical trials of the MicroMed DeBakey VAD (ventricular assist device) began in Europe in November 1998. As of December 1, 1999, 18 patients have been implanted with the MicroMed DeBakey VAD. Hemodynamic evaluations along with blood chemistry analysis were recorded routinely. Exercise tolerance was observed. In most patients, end-organ function has improved and has not deteriorated in any patient. Patients have been able to perform normal low-level activity and have tolerated positional changes without evidence of postural hemodynamic changes. Select patients have taken supervised out-of-hospital excursions. This initial clinical experience with the MicroMed DeBakey VAD suggests that the miniaturized axial flow pump can provide ventricular support to bridge patients to cardiac transplant and may provide an improved quality of life for the end-stage heart failure recipient.

Activities of Daily Living↗
PubMed1999

The DeBakey ventricular assist device: current status in 1997.

In 1993, the development began of a small axial flow blood pump, the DeBakey ventricular assist device (VAD). The material was recently converted to a titanium alloy, and a waterproof pump package was incorporated for long-term intracorporeal circulation. Thirteen intrathoracic implantations in calves were achieved. Nine animals survived the 2 week perioperative period and were supported for a range of 26-93 days. The first study had low flow due to poor anatomical fit of the straight cannula. In contrast, a curved cannula used subsequently provided a good anatomical fit with sufficient flow. Mean flow of 4.4 L/min was sustained with 9,900 rpm and required power was an average of 8.8 W. No thromboembolic evidences were observed in any case, and the plasma free hemoglobin level was maintained lower than 5 mg/dl, except in the early postoperative period. Three animals were terminated because of bleeding due to anticoagulant mismanagement. Electric interference (n = 1) and drive line breakage/fault (n = 2) were observed as device-related failures. Minor modifications were made to the drive line. In conclusion, the DeBakey VAD demonstrated adequate basic performance and biocompatibility. The highly reliable mechanical components and improved electrical parts are promising for a long-term implantable cardiac prosthesis.

Animals↗
PubMed1999

Chronic survival of calves implanted with the DeBakey ventricular assist device.

The DeBakey ventricular assist device (VAD) is a miniaturized, electromagnetically driven axial flow pump capable of generating in excess of 10 L/min output. The VAD was evaluated in 19 calves during experiments designed to test iterative modifications in the system and to determine the safety of the DeBakey VAD for intermediate to long-term implant. Five of the animals died or were euthanized during the perioperative period (i.e., Days 1-5) due to complications associated with bleeding (n = 3), sudden cardiac arrest (n = 1), or pump occlusion due to a muscle remnant associated with coring (n = 1). The remaining 14 animals survived from 7-145 days. Ten of the 14 animals survived 30 or more days, and 2 animals survived 93 and 145 days before elective euthanasia. Pump function was evaluated in the 14 calves that survived beyond the perioperative period. Pump output at implantation averaged 3 L/min while output at 100 days (n = 2) averaged 4.22 L/min. The electrical current did not change across time during the study, indicating normal operation of the bearings. Pumps consumed less than 10.5 W of power for all support durations. Hemolysis did not occur; the average daily plasma free hemoglobin varied from 2.0 to 8.0 mg/dl. Evaluation of serum biochemical data showed that implantation of the DeBakey VAD in calves with normal hearts did not impair end organ function; BUN, creatinine, and total bilirubin varied minimally within the normal range. The white blood cell count of implanted animals remained within the normal range throughout the study.

Animals↗
PubMed1998

Radon-222 and gamma ray levels associated with the collection, processing, transmission, and utilization of natural gas.

The natural gas industry in British Columbia was investigated for exposure to radioactive contaminants such as radon-222 and lead-210. Radon activity associated with the gathering system ranged from 7-921 Bq/m3. The pipelines to the processing facility contained sludge that had a mean lead-210 activity of 0.494 Bq/g (0.379 standard deviation [SD]) and a mean radium-226 activity of 0.417 (0.398 SD). Within the processing facility the highest levels of radon were associated with propane production streams, and activities as high as 4958 Bq/m3 were found. Equipment handling these streams was also found to have a buildup of scale with lead-210, radium-224, and radium-226 activity. The transmission of salable gas to the consumer indicated a decrease in radon activity that was slightly lower than the estimated radon activity based on the half-life of radon, the distance from the production facility, and the speed of gas transmission. The risk of radon exposure to the worker was deemed well below the guidelines and would be controlled more than adequately by means of the occupational standards for the natural gas components. Gamma ray exposure was also well below the occupational standards. Radon exposure to the consumer was virtually nonexistent in the Vancouver region from both natural gas and propane. Although this might not be the case for consumers of propane closer to the production facilities, its contribution is likely to be minimal.

British Columbia↗
PubMed1998

Liquid crystal thermometry for the detection of neonatal hypothermia in Nepal.

We assessed the sensitivity, specificity and likelihood ratio of a low cost liquid crystal strip thermometer (LCT) compared with axillary mercury thermometry for the detection of neonatal hypothermia in Nepal. The subjects were 76 healthy newborns in the government maternity hospital of Kathmandu, Nepal in winter. The validity of LCT for the detection of neonatal hypothermia (less than 36 degrees C) showed a sensitivity of 83 per cent, specificity 96 per cent, positive predictive value 98 per cent and a likelihood ratio of 23. Use of LCT on newborns in this setting raises a measured pretest probability of first day hypothermia of 63 per cent to a post-test probability of 97 per cent. Liquid crystal thermometry is a simple, low-cost, and valid method for identifying core hypothermia in newborns. It is ideal for isolated rural communities where LCT strips could be added to delivery kits.

Female↗
PubMed1998

The 'growth monitoring teaching aid' rapidly improves mothers' understanding of growth curves.

Most growth monitoring programmes in developing countries have not been successful in reducing malnutrition. This is due, at least in part, to the exclusion of mothers from the process of growth monitoring. An essential requisite for greater participation is for mothers to understand the meaning of a growth chart. The 'Growth Monitoring Teaching Aid' (GMTA) is an educational game which attempts to expedite the process of understanding growth curves by simulating the growth curve of a child using water added to a bucket suspended below the direct recording scales. Thirty mothers were divided into an experimental group who used the GMTA for 2-4 h and a control group who did not use it. Six questions were used to test each subject's understanding of growth curves. Paired t tests revealed that the experimental group significantly increased their understanding of growth, whereas the control group did not. The mean score for the experimental group prior to playing the game was 1.43; this increased to 5.27 after playing the game (P < 0.0001). The GMTA by rapidly improving the present poor level of understanding of growth curves, may allow greater maternal participation in growth monitoring.

Adult↗
PubMed1997

Fly traps.

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Animals↗
PubMed1997

Apparatus for emergency transtracheal ventilation.

Twenty anaesthetists were asked what equipment they would use to ventilate a patient after having performed an emergency cricothyroid puncture. Six systems were described and these were assessed for efficiency in delivery of oxygen through a 14 gauge cannula. Delivery of oxygen depended on the pressure achieved within the system. Apparatus utilizing a Bain circuit achieved volumes of around 200 ml for each double-handed squeeze of the reservoir bag. Use of a system taught on the Advanced Trauma and Life Support (ATLS) course resulted in higher system pressures and consequently greater volumes of oxygen delivered. Use of the oxygen flush with this system provides the highest flow rate and system pressure which results in 628 ml being delivered for a one second compression.

Anesthesiology↗