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Biomedical subjects

K M Stewart

Publications and source records attributed to K M Stewart.

14 recordsLinked to original sources
PubMed1999

Carpentier-Edwards standard and supraannular porcine bioprostheses: comparison of technology.

BACKGROUND: Performance with regard to structural valve deterioration (SVD) with the Carpentier-Edwards standard (CE-S) and supraannular (CE-SAV) (Baxter Healthcare Corp, Irvine, CA) porcine bioprostheses was evaluated to determine whether progress in reduction of structural failure has been achieved with technological changes. METHODS: The CE-S was implanted during 567 aortic valve replacement (AVR) and 486 mitral valve replacement (MVR) procedures, and the CE-SAV was implanted during 1,670 AVR and 1,096 MVR procedures. The failure mode of early stent dehiscence with the CE-SAV prosthesis, thought to be controlled by manufacturing changes in 1986 and 1987, supported comparison of the CE-SAV with censored cases of stent dehiscence. Stent dehiscence accounted for only 1.2% (1 of 81) and 14.1% (29 of 205) of AVR and MVR CE-SAV failures, respectively. RESULTS: The only difference for AVR for freedom from SVD occurred in the 21- to 40-year age group at 15 years and was 68% for the CE-SAV and 31% for the CE-S (p<0.05). In the 61- to 70-year age group, freedom from SVD at 15 years was 76% for the CE-S and 84% for the CE-SAV; for the 71-year or higher age group, freedom from SVD was 89% and 95%, respectively (p = NS). For MVR freedom from SVD was different only in the 71-year or higher age group and was 90% for the CE-S and 59% for the CE-SAV (p<0.05). Freedom from SVD was reduced but was similar (p = NS) for the other age groups. For AVR the actual freedom from SVD at 15 years for the CE-S and CE-SAV was, respectively, 79% and 72% for the 51- to 60-year age group, 86% and 91% for the 61- to 70-year age group, and 98% and 98% for the 71-year or higher age group. For MVR, these rates were, respectively, 69% and 75% for the 61- to 70-year age group and 96% and 89% for the 71-year and higher age group. CONCLUSIONS: The technologic advancements made in the second-generation CE-SAV bioprosthesis to reduce the incidence of structural failure have not uniformly been successful. The actual freedom from SVD provides evidence for implantation of porcine bioprostheses for AVR in age groups 61 to 70 years and 71 years or higher and for MVR in the age group 71 years or higher.

Adult↗
PubMed1996

Resting systolic blood pressure, parental history of hypertension, and sensitivity to noxious stimuli.

Increased nociceptive thresholds have been reported in hypertensive rats and humans, and also in normotensive humans at risk for developing hypertension by virtue of elevated resting blood pressure levels or a family history of hypertension. Because risk for hypertension may be more accurately predicted by a combination of risk factors, the present study examined the pain sensitivity of young adult males as a function of resting systolic blood pressure and family history of hypertension. Cold pressor and forearm ischemia tasks were administered in a counterbalanced order. Pain was assessed using numerical rating scales of intensity and unpleasantness during the tasks and the McGill Pain Questionnaire immediately following the tasks. Individuals with a parental history of hypertension obtained significantly lower Pain Rating Index scores on the McGill Pain Questionnaire for both tasks, and also reported significantly lower pain on both numerical rating scales during the ischemic task. No significant relationship was observed between resting systolic blood pressure and measures of pain sensitivity.

Adult↗
PubMed1996

Multipin solid-phase synthesis of acyl 2, 3-diaminopropionic acid oligomers.

A modular approach for the synthesis of sets of diverse organic molecules is described. N-alpha-Fmoc-N-beta-Alloc-D-2,3-diaminopropionic acid (Fmoc-D-Dpr(Alloc)-OH) was prepared in four steps from Boc-D-asparagine and used as a scaffold for attachment of sidechains. Using the Multipin approach, a number of model acyl trimers were rapidly prepared by sequential coupling of Fmoc-D-Dpr(Alloc)-OH and acylation of the beta-amino group with a range of activated carboxylic acids.

beta-Alanine↗
PubMed1996

Exteroceptive suppression of temporalis and masseter muscle activity is enhanced in offspring of hypertensives.

Exteroceptive suppression of temporalis and masseter muscle activity was examined in young men with and without a parental history of hypertension. Recent clinical studies suggest that the second exteroceptive suppression period is attenuated in several chronic pain disorders and that this brainstem reflex may serve as a noninvasive index of endogenous pain control. In the present study, offspring of hypertensives exhibited a significant protraction of the late exteroceptive suppression period for both muscle sites, suggesting that the decreased pain sensitivity previously observed in individuals at risk for hypertension may be related to enhanced central pain modulation.

Electromyography↗
PubMed1995

Prenatal stress attenuates ulceration in the activity stress paradigm.

In the present study, 28 pregnant rats were subjected to either light-restraint stress or no manipulation for days 14-21 of the gestational period. At approx. 50 days of age, both male (n = 16) and female (n = 16) prenatally stressed (PS) and control offspring were subjected to the activity stress (AS) paradigm. During this subsequent stress experience, PS rats developed less ulceration than control rats. PS rats also displayed about half the activity of the control animals during the habituation phase of the AS paradigm, prior to the induction of stress. Given this decrease in baseline activity in PS animals, implications of using activity as a measure of emotionality in PS animals are discussed. Several sex differences were also observed; females differed from males in that they 1) exhibited higher activity levels in both the habituation and experimental phases of the AS procedure, 2) developed heavier relative adrenal weights, and 3) reached criteria for sacrifice in fewer days.

Adrenal Glands↗
PubMed1995

Parental history of hypertension and enhanced cardiovascular reactivity are associated with decreased pain ratings.

Ischemic pain was examined in adult males with and without a parental history of hypertension. Blood pressure and heart rate were recorded during baseline, cold pressor, and ischemia. Repeated pain ratings were obtained during cold pressor and ischemia, and the McGill Pain Questionnaire was completed after each stressor. A median split was used to identify high and low mean arterial pressure and heart rate reactors to cold pressor. Parental history of hypertension, high heart rate reactivity, and high mean arterial pressure reactivity were each associated with significantly lower ischemic pain ratings on the McGill Pain Questionnaire, suggesting that risk for hypertension is associated with hypoalgesia in normotensives.

Adult↗
PubMed1993

The cardiac surgery program at the Royal Columbian Hospital: review of the first fiscal year.

From a budgetary viewpoint, the authors summarize the operative experience of the cardiac surgery program at the Royal Columbian Hospital during its first fiscal year of operation. The program was funded for 250 cardiopulmonary bypass (CPB) procedures: $16,800 per CPB procedure ($4.2 million for the program). The 250 CPB procedures were performed on 248 patients. The 30-day operative mortality was 2%. Thirty patients (12.1%) underwent a second operation for complications or delayed primary closure of the sternum, or both; the complications included aortic prosthetic perivalvular leaks in 2 patients. Eight patients (3.2%) required insertion of an intra-aortic balloon pump preoperatively to stabilize their condition; 10 others (4.0%) required intra-aortic balloon pump insertion at surgery to correct low-cardiac-output syndrome. Blood products were needed for 149 (59.6%) of the 250 CPB procedures. The average hospital stay was 10.4 days for noncoronary procedures and 9.0 days for coronary procedures.

Aged↗
PubMed1993

Alerting patients to the risk of radon.

The potential lung cancer risk from exposure to radon gas and the development of appropriate public health policy have been the subject of much discussion for several years. The American Lung Association has taken a leading role in educating the public on radon and other environmental hazards. This article presents background on radon, including the issues of risk assessment and policy development; reviews the current understanding of the hazards of exposure and the scope of the problem; describes how to test for radon; and discusses how to decrease radon levels.

Adult↗
PubMed1992

The future of environmental health in Scotland.

This paper reviews the considerable progress which the environmental health profession has achieved, particularly during the course of the past 10-20 years. The future of the profession is considered particularly in relation to the development of higher degree opportunities and progress of research, the expanding use of support and associate specialist staff, and the thorny area of meat inspection. Further re-organisation of local government is inevitable and the paper suggests the development of a broader based environmental health and public safety service within local government, mirrored nationally by a similar department at the Scottish Office. The key roles of the Environmental Health (Scotland) Unit and the Royal Environmental Health Institute of Scotland in the future development of the profession are highlighted.

Education, Medical, Graduate↗
PubMed1991

Review and comparison of current trends in the postoperative management of tendon repair.

The precision of the Evans/Burkhalter protocol and the work by Silverman and associates exemplify one of the most valuable of all current trends in rehabilitation of the healing tendon. Knowledge of tendon excursion at each level and throughout the range of motion in each joint gives us safe parameters for tendon mobilization. Hand rehabilitation is becoming more of a science while remaining an art. Research into tendon healing, nutrition, anatomy, biomechanics, and physiology gives us a solid basis for our treatment techniques. We now need to replicate studies already performed and quantify more precisely the data we have. Many questions remain unanswered. There is a wide variety in the position of splinting for flexor tendon mobilization under current protocols: What joint positions are optimal and why? The number and frequency of repetitions in early mobilization protocols varies greatly: What number and frequency is more appropriate for which patients? How much tendon excursion will control adhesions, promote healing, and avoid gap formation or elongation of the repair? How much force should we apply passively to maintain or increase joint motion? How soon should we start active motion, and how can we control the strength of those early muscle contractions? Do "place-hold" exercises truly place less tension on the repair site? How soon should we begin resisted exercise, and how much resistance are we applying with each type of exercise? Should blocking exercises be considered resistive? How should tendon management protocols be adapted in the presence of associated injuries? Lack of space has prevented discussion here of recent and needed research in a number of areas, such as the effectiveness and appropriate precautions for the use of ultrasound, iontophoresis, and neuromuscular electrical stimulation in tendon management. The evidence is growing, but we have a long way to go. To improve our clinical results, the trend toward precision must continue and grow.

Exercise Therapy↗