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Biomedical subjects

D L Carroll

Publications and source records attributed to D L Carroll.

At least 19 recordsLinked to original sources
PubMed2005

Solid-state NMR characterisation of the thermal transformation of a Hungarian white illite.

(1)H, (27)Al, (29)Si and (39)K solid-state NMR are reported from a Hungarian illite 2:1 clay for samples heated up 1600 degrees C. This single-phase sample has a small amount of aluminium substitution in the silica layer and very low iron-content ( approximately 0.4wt%). Thermal analysis shows several events that can be related to features in the NMR spectra, and hence changes in the atomic scale structure. As dehydroxylation occurs there is increasing AlO(4) and AlO(5)-contents. The silica and gibbsite layers become increasingly separated as the dehydroxylation progresses. Between 900 and 1000 degrees C the silica layer forms a potassium aluminosilicate glass. The gibbsite-layer forms spinel/gamma-Al(2)O(3) and some aluminium-rich mullite. Then on heating to 1600 degrees C changes in the (29)Si and (27)Al MAS NMR spectra are consistent with the aluminosilicate glass increasing its aluminium-content, the amount of mullite increasing probably with its silicon-content also increasing, and some alpha-Al(2)O(3) forming.

Journal Article↗
PubMed2004

Optical properties of vanadium oxide nanotubes.

The optical properties of vanadium oxide nanotube dispersions have been characterized using visible and near infrared absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and nonlinear transmission of optical intensities in the visible and near infrared. Using transmission electron microscopy, optical properties have been correlated to the occurrence of two distinct nanoparticle morphologies: nanotubes and unrolled tubes or platelets. Raman spectroscopy indicates that color changes associated with tub unrolling can be attributed to V2O5 formation. The nanotube and platelet morphologies both show strong optical intensity limiting at 532 and 1064 nm. However, dependencies on repetition rate suggest that slightly different mechanisms dominate at the two wavelengths.

Crystallization↗
PubMed2001

Activities of the APN to enhance unpartnered elders self-efficacy after myocardial infarction.

Unpartnered elders recovering from a myocardial infarction find themselves with limited support to contend with their physical and emotional recovery. The advanced practice nurse (APN) can play an instrumental role in improving the health outcomes of these elders. Detailed description of the activities of the APN that affect patient outcomes in current randomized clinical trials have been inadequate in published reports. Therefore, the purpose of this article is to describe the activities of an APN in a nurse-coached intervention study for unpartnered elders post-myocardial infarction. Thematic analysis from the subject logs and narratives from the APN identified the four themes of patient education, validation/feedback, encouragement/support, and problem solving as the unique activities of the APN. These activities enhanced the recovery of these vulnerable unpartnered elders after a myocardial infarction.

Aged↗
PubMed2001

The effects of music on cardiac patients on bed rest.

Hospitalizations that require invasive cardiac procedures or support with an intra-aortic balloon pump can be unsettling. This study was undertaken to measure the effect of a music intervention on physiologic and psychological responses of patients on bed rest due to procedural sheaths or an intra-aortic balloon pump. A randomized, two-group, pretest/post-test design was utilized to measure the effect of a 30-minute music intervention on heart rate, blood pressure, respiratory rate, skin temperature, pain perception, and mood states. One hundred forty subjects participated, 65 in the control group and 75 in the treatment group. There were no significant differences between the groups in demographic, clinical, or baseline variables, except for respiratory rate. After the music intervention, there were reductions in blood pressure, respiratory rate, and psychological distress, as measured by the Profile of Mood States (p < 0.05). Music appeared to affect selected physiologic responses and reduce psychological distress in patients on bed rest.

Affect↗
PubMed2000

The peer advisor experience providing social support.

Research shows a link between increased social support and decreased complications after myocardial infarction (MI). In a current randomized controlled trial (RCT), a social support intervention administered by nurse and peer advisors is being examined to determine its influence on the health outcomes of unpartnered, post-MI elders. This qualitative study (as part of the larger RCT) sought a better understanding regarding the experience of the peer advisor. Data sources included peer advisor logs, a focus group, and telephone interviews with peer advisors. Findings revealed that helping, mutual sharing, committing, and benefiting are characteristics of peer experiences. Primarily because of their personal experience of recovery from MI, peer advisors had a remarkable ability to relate to assigned post-MI elders, offering a unique form of social support complementary to current health practices.

Aged↗
PubMed2000

A knowledge-based patient assessment system: conceptual and technical design.

This paper describes the design of an inpatient patient assessment application that captures nursing assessment data using a wireless laptop computer. The primary aim of this system is to capture structured information for facilitating decision support and quality monitoring. The system also aims to improve efficiency of recording patient assessments, reduce costs, and improve discharge planning and early identification of patient learning needs. Object-oriented methods were used to elicit functional requirements and to model the proposed system. A tools-based development approach is being used to facilitate rapid development and easy modification of assessment items and rules for decision support. Criteria for evaluation include perceived utility by clinician users, validity of decision support rules, time spent recording assessments, and perceived utility of aggregate reports for quality monitoring.

Artificial Intelligence↗
PubMed1998

A new genetic algorithm technique in optimization of permanent 125I prostate implants.

Real time optimized treatment planning at the time of the implant is desirable for ultrasound-guided transperineal 125I permanent prostate implants. Currently available optimization algorithms are too slow to be used in the operating room. The goal of this work is to develop a robust optimization algorithm, which is suitable for such application. Three different genetic algorithms (sGA, sureGA and securGA) were developed and compared in terms of the number of function evaluations and the corresponding fitness. The optimized dose distribution was achieved by searching the best seed distribution through the minimization of a cost function. The cost function included constraints on the periphery dose of the planned target volume, the dose uniformity within the target volume, and the dose to the critical structure. Adjustment between the peripheral dose, the dose uniformity and critical structure dose can be achieved by varying the weighting factors in the cost function. All plans were evaluated in terms of the dose nonuniformity ratio, the conformation number and the dose volume histograms. Among these three GA algorithms, the securGA provided the best performance. Within 2500 function evaluations, the near optimum results were obtained. For a large target volume (5 cm x 4 cm x 4.5 cm) including urethra with 20 needles, the computer time needed for the optimization was less than 5 min on a HP735 workstation. The results showed that once the best set of parameters was found, they were applicable for all sizes of prostate volume. For a fixed needle geometry, the optimized plan showed much better dose distribution than that of nonoptimized plan. If the critical structure was considered in the optimization, the dose to the critical structure could be minimized. In the cases of irregular and skewed needle geometry, the optimized treatment plans were almost as good as ideal needle geometry. It is concluded that this new genetic algorithm (securGA) allows for an efficient and rapid optimization of dose distribution, which is suitable for real time treatment planning optimization for ultrasound-guided prostate implant.

Algorithms↗
PubMed1997

Barriers and facilitators to the utilization of nursing research.

The nurse in clinical practice must demonstrate a scientific base for practice grounded in research findings. The purpose of this study was to explore the nurse's perception of the barriers and facilitators to using research findings in nursing practice. A survey methodology was used, and a sample of 356 practicing registered nurses responded. Data were collected using a scale that rated the barriers and facilitators to research utilization. The greatest barriers were insufficient time on the job to implement new ideas, lack of knowledge of nursing research findings, and inaccessibility of relevant literature. The advanced practice nurse is in a pivotal position to decrease the barriers to research utilization.

Adult↗
PubMed1990

Late results with Carpentier-Edwards porcine bioprosthesis.

From 1977 to 1984, 429 patients underwent aortic valve replacement (AVR), and 339 underwent mitral valve replacement (MVR) with a Carpentier-Edwards bioprosthesis. Early mortality for AVR was 4.6% (isolated AVR, 1.9%) and for MVR was 5.3% (isolated MVR, 4.1%). Follow-up was 99.3% complete at a mean of 5.9 years. Actuarial event-free rates at 10 years for AVR and MVR were, respectively, 1) for structural valve deterioration, 91.4 +/- 3.2% versus 75.1 +/- 4.0% (p less than 0.01); 2) for nonstructural dysfunction, 100% versus 97.8 +/- 1.6% (p = NS); 3) for thromboembolism, 90.6 +/- 2.3% versus 87.3 +/- 2.6% (p = NS); 4) for anticoagulant-related bleeding, 95.3 +/- 1.1% versus 88.6 +/- 2.4% (p = 0.05); 5) for endocarditis, 87.8 +/- 5.7% versus 90.6 +/- 2.4% (p = NS); 6) for reoperation, 91.0 +/- 2.5% versus 74.4 +/- 3.7% (p less than 0.01); 7) for valve-related mortality, 76.1 +/- 6.9% versus 71.4 +/- 5.2% (p = 0.01); 8) for permanent physical impairment, 85.0 +/- 3.0% versus 71.5 +/- 3.6% (p less than 0.01); and 9) for combined operative mortality, valve-related mortality, and reoperation, 68.7 +/- 6.4% versus 51.5 +/- 4.9% (p = 0.01). No structural valve dysfunction was observed in any AVR patient whose valve was inserted after age 70. Age at operation was the only factor that predicted structural valve deterioration (p less than 0.01).

Actuarial Analysis↗
PubMed1989

Comparison of coronary artery bypass grafting and percutaneous transluminal coronary angioplasty as initial treatment strategies.

Early and late results of primary nonemergency coronary artery bypass grafting in 1,000 consecutive patients and primary nonemergency percutaneous transluminal coronary angioplasty performed concurrently in 389 patients were retrospectively compared. The coronary bypass population was significantly older and more symptomatic and had more prior myocardial infarctions, more left main and multiple-vessel coronary artery disease, and poorer ventricular function. Hospital mortality rates for coronary bypass grafting and angioplasty were 0.4% and 0.5%, respectively, and infarction rates were 1.7% and 5.1%, respectively (p less than 0.01). Including hospital events for the coronary bypass and angioplasty populations, actuarial survival at 5 years was 92.3% versus 96.3% (p = 0.04), freedom from myocardial infarction was 94.6% versus 88.1% (p less than 0.001), freedom from subsequent angioplasty was 99.5% versus 75.2% (p less than 0.001), freedom from subsequent coronary bypass grafting was 98.8% versus 84.9% (p less than 0.001), and freedom from all morbidity and mortality was 87.1% versus 66.0% (p less than 0.001), respectively. By Cox regression analysis for all 1,389 patients, only diminished ejection fraction and advanced age predicted poor long-term survival (p less than 0.001). The only significant predictor of nonfatal late events was having had coronary angioplasty.

Angioplasty, Balloon↗
PubMed1987

Event-free survival following nonemergency myocardial revascularization during hypothermic fibrillatory arrest.

To better assess the late results of hypothermic fibrillatory arrest during myocardial revascularization, 1,000 consecutive patients having nonemergency coronary artery grafting during hypothermic fibrillatory arrest from August, 1979, through November, 1984, were studied to determine event-free survival. Hospital mortality was 0.4% and the rate of perioperative myocardial infarction, 1.8%. At follow-up (mean, 30.5 months), 11 patients had sustained an interval nonfatal myocardial infarction, 3 had had percutaneous angioplasty, and 2 had undergone reoperative revascularization. Actuarial survival at five years was 91.6 +/- 2.0%. Actuarial event-free rates at five years were 97.7 +/- 0.8% for myocardial infarction, 99.4 +/- 0.4% for percutaneous transluminal coronary angioplasty, 99.5 +/- 0.4% for reoperative revascularization, and 88.6 +/- 2.2% for all combined morbidity and mortality. Among the 122 patients meeting randomizable admission criteria of the Coronary Artery Surgery Study, there were no operative deaths and no perioperative infarctions, and the actuarial survival was 97.5% at five years. Hypothermic fibrillatory arrest is effective for myocardial preservation during coronary revascularization and when combined with complete revascularization, yields excellent event-free survival.

Actuarial Analysis↗
PubMed1984

Reaction of azapeptides with chymotrypsin-like enzymes. New inhibitors and active site titrants for chymotrypsin A alpha, subtilisin BPN', subtilisin Carlsberg, and human leukocyte cathepsin G.

A series of new azapeptide p-nitrophenyl esters containing a variety of P1 aza-amino acid residues have been synthesized, and the reaction of these azapeptides with chymotrypsin A alpha, subtilisin BPN', subtilisin Carlsberg, and human leukocyte cathepsin G at pH 4-7 has been studied. These azapeptides were found to be very useful as active site titrants and inhibitors of serine proteases with chymotrypsin-like specificity. Stable acyl derivatives of serine proteases are formed in the reaction with azapeptides and can be used for future crystallographic investigations. The effects of changing the nature of the P1' leaving group (-ONp, -OPh, -OCH2CF3, -OEt) for these azapeptides was also investigated. N-Acetyl-L-alanyl-L-alanyl-alpha-azanorleucine p-nitrophenyl ester can be used as an active site titrant for human leukocyte cathepsin G and N-acetyl-L-alanyl-alpha-azaphenylalanine p-nitrophenyl ester is a suitable titrant for chymotrypsin A alpha, subtilisins, or cathepsin G.

Aza Compounds↗
PubMed1984

Reaction of azapeptides with human leukocyte elastase and porcine pancreatic elastase. New inhibitors and active site titrants.

The reaction of a series of azapeptides with porcine pancreatic (PP) elastase and human leukocyte (HL) elastase has been studied and a series of new inhibitors and active site titrants were found for both PP elastase and HL elastase. Azapeptide p-nitrophenyl esters acylate both HL and PP elastase to form stable acylenzymes, which can be used for crystallographic studies. We have investigated the effect of a P1, P2, or P3 aza-amino acid residue on the reactivity of azapeptides with elastase. We have also studied the effect of changing the nature of the P1' leaving group and other portions of azapeptide structure. N-Acetyl-L-alanyl-L-alanyl-alpha-azaalanine p-nitrophenyl ester, N-acetyl-L-alanyl-L-alanyl-alpha-azanorleucine p-nitrophenyl ester, and N-acetyl-L-alanyl-L-alanyl-alpha-azanorvaline p-nitrophenyl ester are suitable titrants for either PP or HL elastase.

Animals↗
PubMed1983

Epidermolysis bullosa--review and report of case.

Hereditary epidermolysis bullosa is reviewed with emphasis on the junctional form (Herlitz-Pearson) (hereditaria letalis). A case report in which concurrent dental restorations and extractions were accomplished is presented.

Child, Preschool↗