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Biomedical subjects

R E Clark

Publications and source records attributed to R E Clark.

At least 127 records · Page 7Linked to original sources
PubMed1995

Psychosocial morbidity in bone marrow transplant recipients: a prospective study.

Previous work has demonstrated that psychosocial morbidity may occur following bone marrow transplantation (BMT), but few prospective quantitative data are available, especially in adults. We have conducted a prospective psychological assessment of 36 patients accepted onto our BMT programme, of whom 31 proceeded to transplant. Patients were assessed shortly before admission for BMT and again at about 4 and 8 months after the procedure, using the following tools: Hospital Anxiety and Depression Scale (HAD), Social Adjustment Scale-Self Report and the Present State Examination (PSE). A 54% incidence of psychosocial morbidity (as assessed by either an abnormal HAD or PSE result) was found among those cases assessed both before and at least once after BMT. Significant psychosocial morbidity was still present 6-9 months following BMT. Cases scoring abnormally following BMT in general also scored abnormally before transplant, suggesting a predictive value of pre-BMT psychological assessment. Psychological morbidity was unrelated to the type of transplant. Patients with chronic myeloid leukaemia had a higher incidence of post-BMT psychosocial morbidity than patients with other diagnoses; it is suggested that this may be due to their lack of previous experience of intensive haematological therapy. Psychological evaluation may help in identifying patients at risk of post-BMT psychosocial problems.

Adolescent↗
PubMed1994

Reacquisition of eyeblink classical conditioning following large cerebellar cortical lesions in Dutch belted rabbits.

The effects of cerebellar lesions on a classically conditioned eyeblink response was examined using Dutch Belted rabbits as subjects. Results confirmed our previous findings, using New Zealand White rabbits, that cerebellar cortical lesions do not abolish conditioned responding if the interpositus is intact. However, unlike our previous studies using New Zealand White rabbits, Dutch Belted rabbits failed to reach a pre-lesion level of performance. These results suggest a possible important strain difference in this paradigm.

Animals↗
PubMed1994

Expenditures of time and money by families of people with severe mental illness and substance use disorders.

Families are typically a major source of support for people with mental illness, but substance abuse places an additional burden on family relations and could reduce the amount of direct support they give. Data from families of 169 people with co-occurring mental illness and substance abuse indicate that they give a substantial amount of time and money to their relatives with dual disorders. More severe current substance abuse appeared to reduce family spending but not direct caregiving. Clients with more severe alcohol problems were more likely to live with parents than with other family members.

Adult↗
PubMed1994

Measuring resource use in economic evaluations: determining the social costs of mental illness.

Concern over costs associated with mental disorders has led to an increase in the number of economic evaluations of treatment interventions; unfortunately, methods for measuring resource use have not kept pace with this concern. Although it is well-known that a significant proportion of the costs associated with mental illness are for resources other than treatment, program evaluators and researchers often count only treatment costs in cost-effectiveness comparisons. Further, existing methods for measuring resource use are plagued by faulty assumptions about resource use, poor validity and reliability, and difficulties quantifying resource use. The authors discuss these problems and suggest five ways of improving measurement of nontreatment resources: clarifying assumptions, using multiple data sources, flexible data collection strategies, methods for improving the accuracy of recall, and an episodic approach to measurement.

Cost of Illness↗
PubMed1994

Extracorporeal membrane oxygenation: preliminary results in patients with postcardiotomy cardiogenic shock.

Long-term survival at our institution for postcardiotomy cardiogenic shock patients supported with the BioPump is 36% (29/80 patients). A heparin-coated extracorporeal membrane oxygenator (ECMO), first introduced in 1991, may reduce organ injury associated with cardiopulmonary bypass. The device can be employed rapidly because it connects directly to the cardiopulmonary bypass cannula. In an effort to improve our results in the treatment of postcardiotomy cardiogenic shock, we used ECMO in 21 patients with this syndrome and accompanying complications. The patients were divided into three groups: group 1, ECMO after coronary artery bypass grafting; group 2, ECMO after mitral valve operation; and group 3, ECMO after open heart operation with prolonged cardiac arrest. Survival in group 1 was 80% with 12 of 14 patients discharged to home. All three deaths were caused by cardiac failure. Bleeding complications in this group were moderate. There was no evidence of disseminated intravascular coagulation, and levels of fibrin split products remained within the normal range. Postoperative complications included stroke (2), renal failure (1), mediastinitis (1), and prolonged respiratory failure (6). Mortality in group 2 was 100%. The major problem limiting recovery was left ventricular distention secondary to inadequate left ventricular decompression. Mortality in group 3 was 100%; all 4 died of brain death. Extracorporeal membrane oxygenation without left ventricular drainage clearly is not effective in patients undergoing mitral valve operations as it does not effectively decompress the left ventricle, but it was highly effective in treating postcardiotomy cardiogenic shock in our coronary artery bypass grafting patients. Extracorporeal membrane oxygenation also proved to be safe as the patient-related complications of stroke, renal failure, and mediastinitis were low. Our preliminary success with heparin-coated ECMO now needs to be confirmed by studies from other centers with larger groups of patients.

Adult↗
PubMed1994

Thromboxane A2 receptor-specific antagonism in hypothermic cardiopulmonary bypass.

Using a thromboxane A2 receptor-specific antagonist, SQ 30,741, this study was undertaken to define the role of thromboxane A2 in postischemic myocardial reperfusion injury and in the heparin-protamine reaction. Eighteen heparinized (300 units/kg) sheep were placed on cardiopulmonary bypass (CPB) after complete instrumentation, cooled to 28 degrees C, and had their aortas crossclamped for 1 hour. They were then rewarmed to 36 degrees C and weaned from CPB without inotropic support. Control sheep (n = 6) received a saline infusion throughout the procedure. Bolus animals (n = 6) received 5 mg/kg of SQ 30,741 at 5 minutes after discontinuation of CPB and before protamine sulfate administration. Infusion animals (n = 6) received an SQ 30,741 bolus of 5 mg/kg followed by a continuous infusion of 5 mg.kg-1 hr-1 of SQ 30,741 initiated before CPB. All animals received 5 mg/kg of protamine sulfate over a 15-second period 15 minutes after being weaned from CPB. Control animals exhibited significantly decreased global myocardial function after the 1-hour ischemic interval. Further significant functional decline and increase in pulmonary pressure occurred after protamine sulfate administration. Bolus animals experienced a similar postischemic injury, but had no further decrease in function following protamine infusion. Infusion animals had significantly improved global myocardial function after bypass compared with both other groups and were also protected from the deleterious effects of protamine sulfate administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Coronary artery bypass grafting: the Society of Thoracic Surgeons National Database experience.

The need for accurate risk assessment has become an indispensable element in the practice of cardiac surgery. The Society of Thoracic Surgeons National Cardiac Surgery Database allows subscribing institutions to perform sophisticated patient risk assessment using traditional statistical tools and a newly developed risk model of operative mortality. The database experience with isolated coronary artery bypass grafting has been studied most closely at this point and serves as the basis for this report. The approach to operative risk assessment is presented along with an analysis of important risk factors in the practice of coronary artery surgery from 1980 through 1990. The database contains records of 80,881 patients undergoing coronary artery bypass grafting in numerous institutions from 1980 through 1990. These records were used to conduct a detailed analysis of risk factors associated with coronary operations in this time interval and to present statistical methods used to formulate a risk equation that allows one to predict the probability of operative death. In the course of this decade, there were clearly defined trends showing a statistically significant increase in adverse patient risk factors. The risk model has proven to be a reliable tool for predicting the probability of operative death in an individual patient and may be valuable in both patient counseling and medical decision making. Large multi-institutional databases of this type are key ingredients of modern operative risk assessment. A database containing a broad national experience of this type can represent an aggregate experience that may well approximate a universally accepted standard of care.

Adult↗
PubMed1994

The Society of Thoracic Surgeons National Database status report.

This report describes the development of the first known national surgical database designed for the practicing community cardiothoracic surgeon. Acceptance by members of The Society of Thoracic Surgeons has been gratifying. The number of patients on the system has grown from 116,109 at the end of 1991 to an anticipated 350,000 to 450,000 by the end of 1993. At the time of this report, 842 surgeons were participating, and more than 1,200 will be on the system by the end of 1993. A risk stratification system has been incorporated into the software, which predicts each patient's risk based on the individual surgeon's past experience. Trend analyses demonstrate a substantial increase in the number of patients at increased risk for perioperative death for coronary artery bypass operations over the past 5 years, while observed mortality has remained relatively constant. Programs are available for adult and congenital heart disease, lung cancer, and esophageal cancer, and modules for mediastinal tumors, pleural disorders, and benign pulmonary disease will soon be added. We anticipate that growth will continue as the need for practice profile data increases because of reimbursement issues.

Age Factors↗
PubMed1994

Impact of internal mammary artery conduits on operative mortality in coronary revascularization.

The long-term advantages of internal mammary artery (IMA) conduits in coronary artery bypass graft (CABG) procedures are widely recognized, but the immediate short-term impact of IMA grafts is not well defined. The purpose of this study was to investigate the influence of IMA conduits on CABG operative mortality (OM). A retrospective study of two groups of patients undergoing isolated CABG was performed. Patients having at least one IMA graft (group 1) were compared with those with only venous conduits (group 2). The patient population was taken from The Society of Thoracic Surgeons National Cardiac Surgery Database, which contains a broad multi-institutional experience. A total of 38,578 registered patients undergoing isolated CABG from 1987 through 1991 were studied. Of these, 18,614 patients had at least one IMA conduit (group 1), whereas 19,964 had CABG using entirely venous conduits (group 2). The OM for group 1 was 2.0% (365/18,614), whereas the mortality was 4.5% (903/19,964) for group 2 (p < 0.005). Patient subgroups were examined to determine if the improved OM associated with IMA grafting was present in these patient subsets. The population was broken down according to age, sex, ejection fraction, extent of coronary disease, and operative priority. For each subset, univariate analysis showed that group 1 OM was significantly less (p < 0.005) than the OM for group 2. Numerous combinations of these patient parameters were also analyzed. Group 1 patients had a significant (p < 0.05) improvement in OM in each combination except for patients more than 70 years of age requiring reoperations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Predictable reduction in left ventricular stroke work and oxygen utilization with an implantable centrifugal pump.

Previous investigations with roller pumps and pneumatic pulsatile assist devices have demonstrated that nearly complete capture of normal left ventricular end-diastolic volume was necessary for appreciable reductions in oxygen consumption and stroke work. We tested the hypothesis that a centrifugal pump would decrease left ventricular stroke work and oxygen consumption as a function of pump flow. Ten sheep (35 to 50 kg) were instrumented and placed on left atrium-to-descending aorta bypass with a small, lightweight (112 g), implantable centrifugal pump. The relations between pump flow as a percent of cardiac output (% bypass), left ventricular stroke work, and oxygen consumption were studied. Left ventricular stroke work was calculated from the pressure-volume loops obtained with micromanometer and conductance catheters and was indexed per 100 g of left ventricular wet weight. Oxygen consumption was calculated from left main coronary artery blood flow and the arterial-coronary sinus oxygen content difference, normalized to 100 g of left ventricular wet weight and a heart rate of 100 beats/min. Measurements were made in stepwise increments of pump flow from zero to the maximum obtainable and then reversed in similar decrements. Analyses were made for 27 complete runs. Our data demonstrate that reductions in left ventricular stroke work and oxygen consumption were achieved from zero to maximal bypass. There was an approximate 66% and 50% reduction in left ventricular stroke work and oxygen consumption, respectively, at 60% bypass.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Practical considerations in the management of large multiinstitutional databases.

Large multiinstitutional databases are excellent sources of information that provide clinically useful insight into the practice of cardiac surgery. Fully informed subscribers should be aware of the practical concerns associated with the management and interpretation of database results. During development of The Society of Thoracic Surgeons National Database, three such areas have become particularly important: the database population, the database quality, and the significance of results. Appreciation of the real and philosophical problems associated with these issues will allow for greater appreciation of the intricacies of the database and will enhance the users' ability to interpret information gained from the database.

Bias↗
PubMed1994

Profile of preoperative characteristics of patients having CABG over the past decade.

The Society of Thoracic Surgeons' National Cardiac Database was used to determine the changes in preoperative characteristics and the predicted and observed risk of operative mortality of patients undergoing coronary artery bypass grafting during the decade of 1984 to 1993. During this period, the data show an increase of 2.5 years in age and decreases of 3% both in incidence of male patients and in incidence of first operation. There was little change in the percentages of urgent/emergent procedures or mean left ventricular ejection fraction. There was a significant 17.5% decrease in the proportion of lowest risk patients (0% to 2.5% predicted mortality) from 61.1% to 43.6%. Although no change in the next higher risk group (> 2.5% to 5.0% predicted mortality) occurred, the higher risk groups showed increases of 6.2%, 9.1%, 1.4%, and 1.1% for the > 5% to 10%, > 10% to 20%, > 20% to 30%, and > 30% to 50% risk groups, respectively. Over the past 2 years, there have been no significant changes in the distribution of the risk groups. These data will provide a base for comparison of future endeavors to lower complication rates and cost of coronary artery bypass graft operations.

Coronary Artery Bypass↗
PubMed1994

Anatomic basis for disk displacement in temporomandibular joint (TMJ) dysfunction.

This study was designed to investigate the site of lateral pterygoid muscle insertion into the temporomandibular joint (TMJ) disk, and the relationship between that attachment and the disk displacement. One hundred and ten TM joints from 78 cadavers were collected and sectioned in the sagittal plane. Sixty-two unilateral specimens were available and 16 additional specimens were selected randomly from the remaining cadavers in which both condyles were available. Thus statistical comparisons were not confounded by autocorrelation and were based on 78 independent specimens. The sites of muscle attachment in relation to the disk were identified histologically. Of the 78 joints 49 had anterior disk displacement. Of the 42 cases with insertion directly into the disk, 30 had anterior disk displacement. In contrast, only 19 of the 36 disks without direct muscle insertion were displaced. This finding indicated a statistically significant relationship between functional muscle attachment and disk displacement (chi 2 = 9.28, df = 1, p = 0.006). However, the superior head of the lateral pterygoid muscle (SLP) may not be the precipitating factor for anterior disk displacement even though it does coordinate disk movement on closure. Since other factors (e.g., trauma) can result in disk displacement, the SLP can maintain disk displacement only when it inserts directly into the disk. In cases of normal disk arrangement and condylar attachment, the muscle may not play a clinically significant role in disk displacement because disk attachment at the medial and lateral poles of the condyle allows the disk to move freely with the condyle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Transfer of learning but not memory after unilateral cerebellar lesion in rabbits.

Unilateral lesion of the cerebellum in rabbits completely and permanently abolishes previous learning and prevents new learning ipsilateral to the lesion. However, when training continues on the contralateral side, there is substantial savings in that it takes few trials to learn. This observation may imply that the memory survives the lesion. Rabbits were classically conditioned for an eyelid response and then the ipsilateral interpositus nucleus of the cerebellum was lesioned. Then the rabbits were trained on the contralateral side. There is no savings on the contralateral side without first trying to train on the lesioned side. The authors conclude that the survival of a memory after the lesion probably does not account for the rapid transfer, but rather that the act of trying to train on the lesioned side in previous studies first induces a new memory on the contralateral side.

Animals↗
PubMed1994

Immunohistochemical margin control applied to Mohs micrographic surgical excision of dermatofibrosarcoma protuberans.

BACKGROUND: Surgical treatment of dermatofibrosarcoma protuberans has a high rate of recurrence presumably secondary to persistent residual tumor. Recently an antigenic marker, CD34, has demonstrated specificity for this tumor. OBJECTIVE: To improve the microscopic detection of dermatofibrosarcoma protuberans tumor elements in Mohs micrographic surgical sections by incorporating immunohistologic staining. METHODS: Standard Mohs micrographic surgical technique was used, coupled with standard immunohistochemical procedures using an antibody to the CD34 antigen. RESULTS: Immunohistochemical staining with anti-CD34 of Mohs micrographic sections clearly delineated the extent of the tumor elements. CONCLUSIONS: We anticipate that the application of this immunohistochemical-modified Mohs surgical technique will further enhance the detection of insidious portions of tumor thereby enhancing removal and reducing recurrence.

Adolescent↗
PubMed1994

Family costs associated with severe mental illness and substance use.

OBJECTIVE: The study's aim was to document the economic assistance in the form of money, in-kind contributions, and time spent in care-giving by families of adults with both severe mental illness and substance use disorders. METHODS: A total of 119 families of adults with dual disorders were compared with a similar group of 127 families whose adult children had no chronic illnesses. In telephone interviews, parents reported the amount of money, goods, and direct care family members gave to a designated adult child. Two methods were used to estimate the value of family time: opportunity costs, based on the average wage for production workers in the study area, and the cost of paid substitutes for the task being performed. RESULTS: Parents of adults with dual disorders reported that family members gave significantly more money and time to the adult child than did parents of adults with no chronic illnesses. The estimated value of family assistance in the dual disorder group was $9,703 using the opportunity-cost method and $13,891 using the substitution method, compared with costs of $2,421 and $3,547 for the group with no chronic illnesses. CONCLUSIONS: Dual disorders impose a significant economic burden on families. Direct support that families provide to adult children with dual disorders should be considered carefully in treatment planning and policy decisions.

Adult↗