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Biomedical subjects

G E Miller

Publications and source records attributed to G E Miller.

At least 19 recordsLinked to original sources
PubMed2001

Results of continual devaluation of cardiothoracic surgical codes by the HCFA between 1984 and 1999.

BACKGROUND: The devaluation of surgical procedural services by Medicare began in 1989 as a result of the federal government's adoption of the Resource Based Relative Value Scale, a method of redistribution of payments to physicians from surgical to primary care services. This method gave to the Health Care Financing Administration (HCFA) effective and complete control of Medicare payments to physicians for the first time. The resultant decrease in the nominal dollar value is well understood, but the effect of changes in inflation frequently is not calculated into the reported loss. METHODS: A method of determining the true extent of this devaluation using the nominal dollar decrease plus the effect of inflation was presented in 1995. RESULTS: Since then, repeated devaluation by the HCFA and other third parties plus continual inflation has further eroded the remuneration for cardiothoracic surgical services. Three different sets of data are used to determine the devaluation of five cardiothoracic operations. One set shows the change between 1988 and 1998; one the change between 1988 and 1999; and one the change between 1984 and 1999. CONCLUSIONS: Depending on the geographic location, it appears that the remuneration for pulmonary procedures between 1988 and 1999 decreased 35% to 60%. Similarly, depending on the years reviewed (between 1984 and 1999) and the geographic location, the fee for cardiac procedures decreased 46% to 69%.

Aortic Valve↗
PubMed2001

Psychological interventions and the immune system: a meta-analytic review and critique.

This article reviews evidence for the hypothesis that psychological interventions can modulate the immune response in humans and presents a series of models depicting the psychobiological pathways through which this might occur. Although more than 85 trials have been conducted, meta-analyses reveal only modest evidence that interventions can reliably alter immune parameters. The most consistent evidence emerges from hypnosis and conditioning trials. Disclosure and stress management show scattered evidence of success. Relaxation demonstrates little capacity to elicit immune change. Although these data provide only modest evidence of successful immune modulation, it would be premature to conclude that the immune system is unresponsive to psychological interventions. This literature has important conceptual and methodological issues that need to be resolved before any definitive conclusions can be reached.

Behavior Therapy↗
PubMed2000

Increased natural killer-cell mobilization and cytotoxicity during marital conflict.

Natural killer (NK) cells are reproducibly mobilized into the circulation in response to intense physical exercise or acute psychological stress, and altered expression of adhesion molecules potentially contributes to NK-cell mobilization. Studies of leukocyte mobilization during acute stress have used psychological stressors which facilitate tight experimental control but have limited applicability to everyday life. We therefore used a laboratory model of marital conflict as an experientially meaningful acute stressor to elucidate relationships among conflict, cardiovascular reactivity, and altered leukocyte phenotype and function. Forty-one ethnically diverse, nondistressed, healthy married couples were asked to discuss a specific problem in their marriage for 15 min. Blood pressure and heart rate were measured before, during, and after the discussion, and blood was remotely drawn at the same time points to quantify numbers of specific leukocyte subsets, NK-cell adhesion molecule expression, and NK cytotoxicity. Couples responded to the conflict task with cardiovascular reactivity; increases in the percentages of circulating NK cells and CD8(+) T cells and decreases in the percentage of circulating CD4(+) T cells; decreases in the percentage of NK cells that express L-selectin; and increases in NK-cell cytotoxicity without a commensurate increase in per-cell cytotoxicity. Rapid downregulation or shedding of L-selectin (CD62L) from NK cells did not contribute to their mobilization during conflict. Instead, CD62L(-) NK cells were mobilized while CD62L(+) NK cells were selectively retained in the vascular marginating pool and/or in extravascular tissue. From a broader perspective, the data support the hypothesis that altered trafficking of specific leukocyte subsets is an integral component of the fight-or-flight response to an acute stressor.

Adult↗
PubMed1999

Personality and tonic cardiovascular, neuroendocrine, and immune parameters.

Although there is now abundant evidence that certain personality features constitute risk factors for negative health outcomes, personality measures have received little attention to date in the behavioral immunology literature. The present study assessed the relationship between major dimensions of personality and tonic cardiovascular, neuroendocrine, and immunologic parameters in 276 healthy adults. Participants who scored low in agreeableness tended to have higher levels of systolic blood pressure, diastolic blood pressure, and epinephrine. Low levels of extraversion were associated with higher blood pressure, epinephrine, norepinephrine, and natural killer cell cytotoxicity. Neuroticism was generally unrelated to physiologic outcomes. Personality was not associated with leukocyte subset counts. The magnitude of relationships between personality and physiology was modest, with personality measures accounting for 1 to 7% of the variance in selected physiological parameters. Health practices did not mediate associations between personality and physiologic outcomes. However, a substantial proportion of the relationship between extraversion and natural killer cell cytotoxicity was accounted for by their common association with epinephrine and to a lesser extent norepinephrine. These findings are consistent with the notion that personality contributes to basal physiology and provide a foundation for further research on the relationship between personality and natural killer cell cytotoxicity.

Adolescent↗
PubMed1999

Psychosocial predictors of natural killer cell mobilization during marital conflict.

This study examined how specific emotions relate to autonomic nervous and immune system parameters and whether cynical hostility moderates this relationship. Forty-one married couples participated in a 15-min discussion about a marital problem. Observers recorded spouses' emotional expressions during the discussion, and cardiovascular, neuroendocrine, and immunologic parameters were assessed throughout the laboratory session. Among men high in cynical hostility, anger displayed during the conflict was associated with greater elevations in systolic and diastolic blood pressure, cortisol, and increases in natural killer cell numbers and cytotoxicity. Among men low in cynical hostility, anger was associated with smaller increases in heart rate and natural killer cell cytotoxicity. These findings suggest that models describing the impact of stress on physiology should be refined to reflect the joint contribution of situational and dispositional variables.

Adult↗
PubMed1999

Shaft/shaft-seal interface characteristics of a multiple disk centrifugal blood pump.

A multiple disk centrifugal pump (MDCP) is under investigation as a potential left ventricular assist device. As is the case with most shaft driven pumps, leakage problems around the shaft/shaft seal interface are of major interest. If leakage were to occur during or after implantation, potential events such as blood loss, clotting, blood damage, and/or infections might result in adverse effects for the patient. Because these effects could be quite disastrous, potential shaft and shaft seal materials have been investigated to determine the most appropriate course to limit these effects. Teflon and nylon shaft seals were analyzed as potential candidates along with a stainless steel shaft and a Melonite coated shaft. The materials and shafts were evaluated under various time durations (15, 30, 45, and 60 min), motor speeds (800, 1,000, 1,200, and 1,400 rpm), and outer diameters (1/2 and 3/4 inches). The motor speed and geometrical configurations were typical for the MDCP under normal physiologic conditions. An air and water study was conducted to analyze the inner diameter wear, the inner temperature values, and the outer temperature values. Statistical comparisons were computed for the shaft seal materials, the shafts, and the outer diameters along with the inner and outer temperatures. The conclusions made from the results indicate that both the tested shaft seal materials and shaft materials are not ideal candidates to be used for the MDCP. Teflon experienced a significant amount of wear in air and water studies. Nylon did experience little wear, but heat generation was an evident problem. A water study on nylon was not conducted because of its molecular structure.

Air↗
PubMed1999

Analysis of optimal design configurations for a multiple disk centrifugal blood pump.

A multiple disk centrifugal pump was analyzed as a blood pump for use in cardiac assistance or as a bridge to transplant device. The original configuration consisted of 6 parallel disks with 0.016 inch spacing between disks. This pump suffered from a degradation of flow with increasing afterload. A study was conducted to analyze flow performance as a function of afterload, preload, and motor speed. Configurations were examined including 4, 5, and 6 disks each with spacings of 0.15, 0.20, and 0.25 inches. Flow rates were examined for variations in afterload from 60-130 mm Hg, in preload from 0-20 mm Hg and for motor speeds of 1,250, 1,500, and 1,750 rpm. Analyses of afterload effects were intended to determine those configurations that produced less flow degradation with increasing afterload. Analyses of motor speed effects were intended to determine any configurations that produced greater flow increases with increasing motor speed. A hemolysis study was also performed. Both plasma free hemoglobin and the index of hemolysis were compared to data reported for other centrifugal blood flow devices. Results indicated that a 5 disk configuration with a 0.15 inch spacing produced optimal flow results with minimal degradation at higher afterloads. No optimal configuration based upon motor speed was indicated. Preload effects on pump performance were minimal. Hemolysis results indicated minimal blood damage with levels below those of many other centrifugal blood pump designs.

Animals↗
PubMed1999

Nondelinquent youths' stealing behavior and their perceptions of parents, school, and peers.

Correlates of stealing behavior were investigated in a sample of 167 nondelinquent 10- to 15-year-olds. Stealing was related to youths' attitudes toward parents and school, as well as reasons for stealing. Stealing was most frequent among older males. Attitude toward school was most consistently related to stealing behavior, though perceptions of family's values and the consequences of stealing were also important. Interventions with youths at risk for continued covert antisocial behaviors are discussed.

Adolescent↗
PubMed1998

Social relationships and the progression of human immunodeficiency virus infection: a review of evidence and possible underlying mechanisms.

We review studies examining the quality and quantity of social relationships as potential risk factors for differential progression of human immunodeficiency virus (HIV) infection. Several well-conducted prospective studies suggest that the health effects associated with the presence of supportive social relationships vary according to disease stage and mode of transmission. For gay or bisexual males in the early stages of infection, the presence of supportive social relationships appears to be a risk factor for accelerated disease progression. For individuals in the later stages of infection and those who acquire HIV via intravenous drug use or transfusion, supportive social relationships appear to be associated with health protective effects similar to those observed in other disease settings. We consider a variety of potential explanations for accelerated disease progression in gay men with extensive networks of personal relationships.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Social relationships and immune processes in HIV seropositive gay and bisexual men.

This three-year longitudinal study assessed the association between social relationships and human immunodeficiency virus (HIV) progression in individuals at risk for morbidity and mortality due to acquired immune deficiency syndrome (AIDS). Two-hundred five HIV seropositive men without AIDS completed measures of social integration and loneliness at baseline. Blood samples used to assess CD4 T-lymphocyte levels were collected at baseline and at six-month intervals for a three-year follow-up period. Contrary to expectation, lower levels of baseline loneliness predicted more rapid declines in CD4 levels over the follow-up period. This association was independent of baseline CD4 values, negative affect, and health practices. A series of mediational analyses revealed that sexual behavior, medication use, bereavement, coping, and a number of other variables were not mechanisms through which loneliness affected the immune system. Loneliness was not associated with time to AIDS diagnosis or time to AIDS-related mortality. These findings are consistent with the emerging view that social relationships can have deleterious, as well as protective, influences on health outcomes.

Acquired Immunodeficiency Syndrome↗
PubMed1996

An asymptotic test for the equality of coefficients of variation from k populations.

The coefficient of variation is often used as a guide of the repeatability of measurements in clinical trials and other medical work. When possible, one makes repeated measurements on a set of individuals to calculate the relative variability of the test with the understanding that a reliable clinical test should give similar results when repeated on the same patient. There are times, however, when repeated measurements on the same patient are not possible. Under these circumstances, to combine results from different clinical trials or test sites, it is necessary to compare the coefficients of variation of several clinical trials. Using the work of Miller, we develop a general statistic for testing the hypothesis that the coefficients of variation are the same for k populations, with unequal sample sizes. This statistic is invariant under the choice of the order of the populations, and is asymptotically chi 2. We provide an example using data from Yang and HayGlass. We compare the size and the power of the test to that of Bennett, Doornbos and Dijkstra and a statistic based on Hedges and Olkin.

Clinical Trials as Topic↗
PubMed1996

Mechanical valves.

Explore the source record for details and available documents.

Anticoagulants↗
PubMed1995

Changing surgical CPI valuation relationships: a method of determination (1970-1995).

Surgeons have, over the past 7 years, experienced a significant decrease in valuation of their services. This has been accomplished by use of the Resource-Based Relative Value System, and its interpretation and modification by various agencies of the federal government. Congress recently mandated a study of practice costs that could result in further reductions of up to 30%. In anticipation of this further reduction, it is important to understand in as accurate a way as possible what has happened thus far to the value for surgical services. Simple percentage in decrease of fees is well understood, but their decrease in relation to the cost of a constant market basket of goods has not been well publicized. We present a simple method for determining the change in value for any procedure or service done by a surgeon in relation to the cost of a constant market basket of goods for any period of time from 1970 to 1995. For example, the increase in the cost for the constant market basket of goods between 1972 and 1992 is shown to be 236%. The increase in value for a typical cardiothoracic procedure in the same time period was 52%. The valuation for this procedure has actually declined 55% from 1972 to 1992, relative to the market basket of goods. The service that would buy the complete basket in 1972 will now buy only 45% of the basket.

Fee Schedules↗
PubMed1995

A preliminary flow visualization study in a multiple disk centrifugal artificial ventricle.

Flow patterns in a multiple disk centrifugal pump were analyzed so that the device could be incorporated as a ventricular assist or a bridge-to-transplant device. The pump operates either in pulsatile or steady flow modes with the ability to change modes within a fraction of a second. The pump was tested on a mock circulatory system consisting of an arterial fluid capacitor, a systemic resistor, and a venous capacitor. Arterial volume flow rate, arterial pressure, inlet (venous) pressure, and pump rotation speed are continually monitored. A glycerin/water solution is used as a blood analog. Flow visualization was performed with a 3 mW yellow laser, sheet lens, neutrally buoyant amberlite particles, and both still and motion picture photography. Flow patterns matched theoretical predictions very well; inlet flow spread radially outward through the disk annular spaces while propelled by shear and centrifugal forces.

Blood Cells↗
PubMed1994

Family-based treatment for childhood antisocial behavior: experimental influences on dropout and engagement.

Antisocial behavior in childhood and adolescence is an unquestionably serious problem for society. Family-based treatments are promising but face the challenging obstacle of premature parental dropout. To systematically study dropout, we randomly assigned 147 families with a markedly aggressive child (age 4 to 9 years) to a standard family treatment (SFT) focusing exclusively on parental management or to an enhanced family treatment (EFT) that also promoted frequent discussions of adult issues. EFT produced a significantly lower dropout rate than SFT overall, but particularly for high-adversity families. Dropouts were clearly distinguishable from completers on several dimensions. The results underscore the importance of addressing contextual variables such as family adversity in the treatment of childhood antisocial behavior.

Adolescent↗