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Biomedical subjects

S Irwin

Publications and source records attributed to S Irwin.

At least 19 recordsLinked to original sources
PubMed2001

Clinical experience with the MicroMed DeBakey ventricular assist device.

BACKGROUND: The MicroMed DeBakey ventricular assist device (VAD) (MicroMed Technology, Inc, Houston, TX) is the first long-term axial flow circulatory assist device to be introduced into clinical trials as a bridge to transplantation. Clinical trials began in Europe in November 1998 and in the United States in June 2000. METHODS: To qualify for the study, the patients must be listed for cardiac transplantation and must have demonstrated profound cardiac failure. There were no exclusions to the MicroMed DeBakey VAD implant other than those patients who would typically be excluded from cardiac transplantation. RESULTS: As of September 2000, 51 patients have been implanted with the MicroMed DeBakey VAD. A detailed evaluation of the first 32 patients has been completed. With current data, the probability of survival at 30 days after VAD implant is 81%. CONCLUSIONS: The clinical trial demonstrated that the MicroMed DeBakey VAD is capable of providing adequate circulatory support in patients with severe heart failure, sufficient to recover and return to normal activities while awaiting a heart transplantation. Much has been learned about the function of the device and its continuous flow in humans.

Equipment Design↗
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

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↗
PubMed2000

Market returns? Gender and theories of change in employment relations.

This paper explores recent arguments about the marketization of female labour, in the context of a wider analysis of the role of concepts like 'the market' and 'individualization' in sociological accounts of change in employment relations. It will be argued that within sociology there has been a tendency for rapid, large-scale changes in employment relations to be characterized as the breakdown of social influences or structures and as the emergence of atomized, individuated market forces. In the most recent models, change in the nature of gendered positions within employment are presented in terms of a decline of social structuring and social constraint. These emergent accounts hold similarities to classical economics, and to Marx's and Weber's accounts of employment, which also characterized new forms of employment relations in terms of the emptying of their social content and their replacement by market forms. We offer an alternative, moral economy, perspective which foregrounds the continued significance of social relations in the structuring of employment and employment change. We develop the argument through an analysis of gendered patterns of employment and change in family form.

Employment↗
PubMed1999

Acute and temporary ventricular support with BioMedicus centrifugal pump.

BACKGROUND: Short-term ventricular and pulmonary support can be provided by the Medtronic BioMedicus (Eden Prairie, MN) centrifugal pump, which is available in most cardiovascular surgery centers. This versatile pump can provide support during cardiopulmonary resuscitation, cardiopulmonary bypass, extracorporeal membrane oxygenation, and ventricular assistance. A common use of the pump is to provide ventricular assistance for patients after cardiotomy or cardiogenic shock. METHODS: From January 1986 to September 1995, 141 patients at The Methodist Hospital in Houston, Texas were placed on the BioMedicus centrifugal pump after postcardiotomy cardiac failure. Patient treatment and postimplant complications are discussed. RESULTS: Fifty-four percent of the patients were weaned; however, only 22% survived to discharge. There was a very high mortality rate in the early stage after support was discontinued, after weaning, and after device removal. CONCLUSIONS: A high incidence of complications and death is likely related to the period of attempted weaning from cardiopulmonary bypass before the initiation of ventricular support. When weaning a patient from the pump during cardiopulmonary bypass or during ventricular assistance, it is important to optimize preload, after-load, ventricular function, and cardiac rhythm. In patients who have had postcardiotomy support, avoiding fluid overload, low colloid oncotic pressure, hypoperfusion, and use of excessive inotropic and vasoactive medications improve results.

Adolescent↗
PubMed1999

Adaptation and validation of a radioimmunoassay kit for measuring plasma cortisol in turbot.

Levels of cortisol in fish blood provide quantitative information on the degree of stress induced by a variety of stressors. It is also useful in describing the social status of individual fish within groups. The commercial production of radioimmunoassay (RIA) kits, such as the DPC Coat-A-Count radioimmunoassay kit, has considerably reduced the effort required for cortisol measurement. These kits employ human plasma based cortisol standards which are not compatible for use with non mammalian species such as fish e.g. turbot, Scophthalmus maximus (Rafinesque), blood due to the interference effect of lipids and steroid binding proteins present in the plasma. In this study the DPC kit was used following the removal of these lipids and steroid binding proteins from the plasma using an ethanol-hexane extraction. Excessive variability in the cortisol values obtained using this method deemed it unsatisfactory in overcoming the problem of incompatibility. A second modification of this technique that was tested involved the preparation of turbot specific standards for use in the preparation of modified standard curves. Using this method, an accuracy of 93.4% was achieved, as opposed to 79.6% using the kit human plasma based standards, and 47.1% using samples following lipid removal using an ethanol-hexane extraction. Based on analysis of accuracy, precision and reproducibility it is concluded that commercially available cortisol kits are suitable for use with turbot plasma, but a number of minor modifications are necessary.

Animals↗
PubMed1999

Knee instability.

Explore the source record for details and available documents.

Anterior Cruciate Ligament↗
PubMed1996

Age related distributive justice and claims on resources.

The ageing population structure, and claims on resources by non-working groups, are seen by many to be contributing to a growing welfare crisis. In their arguments, relations between age groups and generations will become increasingly fraught, and welfare arrangements will be undermined, as 'unacceptable' levels of taxation blight the experience of a contracting workforce, required to resource a growing welfare population. However, more seems to be known about researchers' views on distributive justice than is known about the perceptions of their subject populations. It has not been demonstrated that members of age groups share interests which are consonant with their cohort experience, or perceive their interests to be in conflict with those members of other age groups or generations. This paper analyses empirical evidence on people's perceptions of who should get, and do, what, in developing an argument that standard processes do not place age groups or generations in antagonistic relationship. Understanding the relations between age groups and generations is essential to explaining change in patterns of inequality, but the interdependence of these relations suggest that they are part of a coherent social structure, and not likely to give rise to crisis in the ways predicted.

Adolescent↗
PubMed1990

DNA specificity of the Cre recombinase resides in the 25 kDa carboxyl domain of the protein.

The Cre protein of bacteriophage P1 is a 38.5 kDa site-specific recombinase that belongs to the Int family of recombination proteins. Cre acts by binding specifically to a 34 base-pair sequence, lox, where it carries out recombination. A limited chymotryptic digest of Cre resulted in two fragments of sizes 25 and 13.5 kDa, respectively. The sequence of the amino terminus of the purified 25 kDa peptide demonstrates that this peptide represents the carboxyl-terminal portion of the Cre protein. A truncated version of the cre gene was constructed which produces only the 25 kDa peptide. The 25 kDa peptide is capable of specific binding to the lox site, but binds at lower affinity than does wild-type Cre. Footprinting with Fe-EDTA indicates that the 25 kDa peptide protects the inverted repeats of the lox site but shows only partial protection of the spacer region. This is in contrast to the footprint obtained with wild-type Cre which protects the entire spacer region.

Amino Acid Sequence↗
PubMed1989

Compliance and the patient's perspective: controlling symptoms in everyday life.

Non-compliance with medical advice is poorly understood. Most of the existing literature considers the problem only from the doctor's point of view. We undertook a diachronic, qualitative study of the illness experiences of 19 women to try to understand non-compliance from the patient's perspective. Three-fourths of our study group had ceased to follow their doctor's recommendations by four months post-diagnosis. Their non-compliance could not be explained by the fact that the women held understandings of their illnesses which were incongruent with their physician's; nor were they unable to understand the diagnosis they received. A consideration of the roles that their diagnosis and treatments played in their daily lives proved more useful in explaining their failure to follow physicians' recommendations. Patients' use of treatments reflected their desire to control symptoms within the constraints of their daily routines.

Activities of Daily Living↗
PubMed1989

Views of what's wrong: diagnosis and patients' concepts of illness.

A group of women were interviewed about their construction of their illness experiences before they saw a physician and subsequently over a period of several months following consultation. It was found that the physician's input was one of many components of their post-consultation understanding of their illnesses. The women built up their understandings in an interactive process, drawing significantly on their prior histories, ongoing experiences and social worlds. They continually tried out, adjusted and reworked the construction of their illnesses to adapt them to the exigencies of everyday life. We conclude that illness explanations are dynamic entities whose adequacy is determined by their usefulness within the extra-medical social environment.

Adult↗
PubMed1985

Clinical manifestations and assessment of ischemic heart disease.

This article reviews five clinical techniques for measuring and assessing the manifestations of ischemic heart disease. These measurements are heart rate, blood pressure, electrocardiogram, symptoms, and changes in heart sounds. The data obtained from these measurements are discussed in relation to measurement accuracy and to their clinical significance and relationship with the patient's diagnosis, prognosis, and disease manifestations. These clinical measures provide information that is critical to the decision-making processes for patient programming and safety.

Angina Pectoris↗