Simultaneous measurement of coronary flow reserve by left anterior descending coronary artery Doppler and great cardiac vein thermodilution methods

OBJECTIVES

The objective of this study was to compare left anterior descending coronary artery Doppler blood flow velocity and great cardiac vein thermodilution blood flow measurements of coronary flow reserve and submaximal coronary vasodilation in humans.

BACKGROUND

Reported maximal coronary flow reserve values obtained with the coronary venous thermodilution method are lower than those obtained with other measurement methods.

METHODS

Thermodilution measurements of great cardiac vein flow in 11 subjects were compared with simultaneous Doppler measurements of changes in left anterior descending coronary flow velocity after intracoronary administration of papaverine, nitroglycerin, iohexol and intravenous administration of dipyridamole.

RESULTS

Coronary flow reserve (papaverine peak/rest flow ratio) was 3.7 +/- 1.7 (mean +/- SD) by the Doppler method and 2.0 +/- 0.7 by the thermodilution technique (p less than 0.001). Thermodilution flow changes were also smaller than Doppler-measured changes during submaximal vasodilation and during prolonged coronary dilation after dipyridamole administration.

CONCLUSIONS

Coronary flow reserve and submaximal flow increases measured with the thermodilution method were consistently and substantially smaller than Doppler-derived measurements. This discrepancy has important implications for the comparison of coronary flow reserve measurements performed with the use of different techniques.

Activated T cells and eosinophilia in bronchoalveolar lavages from subjects with asthma correlated with disease severity

Activated T-lymphocytes may regulate the eosinophilic inflammation of bronchial asthma. In the present study, we investigated T cell activation and eosinophilia in blood and bronchoalveolar lavage (BAL) in 17 patients with asthma not receiving steroid treatment. Compared to normal individuals, BAL from patients with asthma contained significantly increased numbers of both lymphocytes and eosinophils (EOSs). The lymphocytosis consisted of increased numbers of both CD4+ and CD8+ T cells, and these T cell populations expressed elevated levels of T cell activation markers (interleukin-2 receptor [CD25], HLA-DR, and very late activation antigen 1). Close correlation was found between numbers of BAL CD4+ IL-2R+ T cells and numbers of EOSs. Moreover, the numbers of activated T cells and EOSs were related to the severity of asthma as measured by impairment of FEV1 and increased methacholine bronchial responsiveness. We demonstrate in both blood and BAL a close correlation between T cell activation, eosinophilia, and severity of asthma, suggesting that recruitment and activation of lymphocytes and EOSs are fundamental to the pathogenesis of bronchial asthma.

[Doppler echocardiographic determination of the effective orifice area of mechanical heart valve prostheses in a flow model]

In a flow model the effective orifice areas (Ae) of 17 mechanical heart valve prostheses were determined. We measured the Ae-values of several sizes of three types of mechanical prostheses (Medtronic-Hall, St. Jude Medical, and Omnicarbon) under quasi-steady flow conditions using the continuity equation: Ae = flow/maximal transprosthetic velocity. The flow through the model could be determined exactly by directly measuring the decreasing fluid level within the feed tank, while the maximal velocities were calculated from CW-Doppler echocardiographic spectra. It was found that 1) over a range of 200-800 cm3/s Ae was constant for all prostheses and 2) in small aortic prostheses the Ae could be determined with only little scattering of the obtained values, while in large mitral prostheses there was a considerable variation within the results of repeated investigations. For example, in the 21- and 31-Omnicarbon-valves mean values of Ae were calculated as 1.41 and 4.03 cm2, respectively, with standard deviations of 0.05 and 0.49 cm2 as a result of about 70 single calculations in each valve. 3) The absolute values of Ae were smaller than those of comparable in vitro studies based on the Gorlin formula. We conclude that the effective orifice areas of prosthetic heart valves can be easily determined in a flow model by the combination of flow and Doppler echocardiographic measurements. As determinations are based on the same principle, the obtained values should clinically be referred to patients where the corresponding continuity equation for pulsatile flow is used as Ae = stroke volume/time integral of the maximal transvalvular velocity.

Polypeptides and bacteriochlorophyll organization in the light-harvesting complex B850 of Rhodobacter sphaeroides R-26.1

The light-harvesting complex (LHC) B850 from Rhodobacter sphaeroides was dissociated into several fragments by treatment with sodium dodecyl sulfate. The molecular weight of each fragment was determined by using transverse polyacrylamide gel electrophoresis under nondenaturing conditions and gel filtration techniques. Four B850 LHCs were observed, having molecular weights of 60,000, 72,000-75,000, 105,000, and 125,000-145,000, and two small bacteriochlorophyll (Bchl)-polypeptide complexes having molecular weights of 6000-8000 and 12,000-14,000. Each of the B850 complexes contains ca. one Bchl a for each 6.5-kDa protein. The optical absorption and circular dichroism of the B850 LHCs recorded directly from the gels are similar to those measured previously for a 22-24-kDa B850 LHCs by Sauer and Austin [(1978) Biochemistry 17, 2011-2019]. These data, combined with studies of other groups, indicate that the smallest LHC in LH1 and LH2 is a Bchl-polypeptide tetramer. Each tetramer contains two Bchl dimers that probably have the structure of P-860, the primary electron donor in Rhodobacter sphaeroides, and two alpha-beta-polypeptide pairs. Interactions among the paired Bchls shift their individual Qy transitions from 780-800 to 850-860 nm, and interactions among two such pairs induce the circular dichroism signal of the LHCs. Three Bchl-polypeptide tetramers probably form a dodecamer having C3 symmetry, and six such dodecamers organize into a large hexagon that can accommodate one or two reaction center complexes.

D1-D2-cytochrome b559 complex from the aquatic plant Spirodela oligorrhiza: correlation between complex integrity, spectroscopic properties, photochemical activity, and pigment composition

A D1-D2-cyt b559 complex with about four attached chlorophylls and two pheophytins has been isolated from photosystem II of the aquatic plant Spirodela oligorrhiza and used for studying the detergent-induced changes in spectroscopic properties and photochemical activity. Spectral analyses (absorption, CD, and fluorescence) of D1-D2-cyt b559 preparations that were incubated with different concentrations of the detergent Triton X-100 indicate two forms of the D1-D2-cyt b559 complexes. One of them is photochemically active and has an absorption maximum at 676 nm, weak fluorescence at 685 nm, and a strong CD signal. The other is photochemically inactive, with an absorption maximum at 670 nm, strong fluorescence at 679 nm, and much weaker CD. The relative concentrations of the two forms determine the overall spectra of the D1-D2-cyt b559 preparation and can be deduced from the wavelength of the lowest energy absorption band: preparations having maximum absorption at 674, 672, or 670.5 nm have approximately 20, 60, or 85% inactive complexes. The active form contains two chlorophylls with maximum absorption at 679 nm and CD signals at 679 (+) and 669 nm (-). These chlorophylls make a special pair that is identified as the primary electron donor P-680. The calculated separation between the centers of these two pigments (using an extended version of the exciton theory) is about 10 A, the pigments' molecular planes are tilted by about 20 degrees, and their N1-N3 axes are rotated by 150 degrees relative to each other. The other two chlorophylls and one of the two pheophytins in the D1-D2-cyt b559 complex have their maximum absorption at 672 nm, while the maximum absorption of the photochemically active pheophytin is probably at 672-676 nm. During incubation with Triton X-100, the photochemically active complex is transformed into an inactive form with first-order kinetics. In the inactive form the maximum absorption of the 679 nm absorbing Chls is blue-shifted to 669 nm. The first-order decay of the photochemical activity suggests that the isolated D1-D2-cyt b559 complex is stable as an aggregate but becomes unstable on dissociation into individual D1-D2-cyt b559 units.

Myocardial preservation using lidocaine blood cardioplegia

Prevention of ventricular fibrillation after aortic unclamping using lidocaine hydrochloride as an additive to cold potassium blood cardioplegia was studied prospectively in 46 patients undergoing elective myocardial revascularization. Patients were similar with respect to age, ventricular function, severity of coronary artery disease, cross-clamp time, completeness of revascularization, frequency of internal thoracic artery grafting, systemic temperature at the time of cross-clamp removal, and mean infusate volume and temperature. Patients receiving lidocaine blood cardioplegia (group 1, 23 patients) had a significant reduction in the incidence of ventricular fibrillation (22% versus 74%; p less than 0.0005) and in the mean number of cardioversion attempts required to defibrillate the heart (0.5 +/- 1.3 versus 1.9 +/- 0.97; p less than 0.0005) after cross-clamp removal compared with controls (group 2, 23 patients). There were no differences between the two groups postoperatively with regard to cardiac enzyme release, hemodynamic measurements, or clinical outcome. Patients receiving lidocaine blood cardioplegia tended to have a lower incidence of new postoperative atrial fibrillation (9% versus 26%). Ventricular function was preserved equally in both groups. We conclude that lidocaine is a safe additive to potassium blood cardioplegia and significantly reduces the incidence of ventricular fibrillation after aortic unclamping.

Refinement and expansion of the Harvard Resource-Based Relative Value Scale: the second phase

The Harvard resource-based relative value scale (RBRVS) for physician services has assumed a critical role in physician payment reform. We have demonstrated that the relative resource costs of providing physician services can be defined and measured in a rational and systematic way and that the results are reliable and valid. Consequently, the RBRVS is a viable basis for national payment policy and could be used for establishing a national fee schedule for physician services or to identify "mispriced" physician procedures. Since the release of the final report of the first phase of the Harvard RBRVS study in September of 1988, there has been extensive review, discussion, and criticism of the RBRVS. Dr. Laurence F. McMahon, Jr., in the accompanying article, provides a further critique of our research. In this paper, we review the RBRVS study and results and respond to the major criticisms that have been raised by Dr. McMahon and others. We then describe the tasks we are currently undertaking to expand and validate our research and address the important criticisms and limitations.

Core symptoms of posttraumatic stress disorder unimproved by alprazolam treatment

The authors report a random-assignment, double-blind crossover trial comparing alprazolam and placebo in posttraumatic stress disorder (PTSD). Ten patients fulfilling DSM-III criteria for PTSD completed 5 weeks of treatment on each agent. Improvement in anxiety symptoms was significantly greater during alprazolam treatment but modest in extent. Symptoms specific to PTSD were not significantly altered. The impact of nonspecific symptomatic effects on the outcome of drug trials in PTSD is considered.

Cyclosporine and anti-interleukin 2 receptor monoclonal antibody therapy suppress accelerated rejection of rat cardiac allografts through different effector mechanisms

Increasing numbers of sensitized patients are either precluded from receiving an allograft or experience accelerated rejection which may be refractory to conventional therapy. Using a rat model, we have shown that accelerated (24 hr) rejection of LBN cardiac Tx in LEW rats sensitized with BN skin grafts 7 days earlier, could be prevented by treatment with cyclosporine (15 mg/kg/day x7 days, Tx survival about 42 days) or ART-18, an anti-IL-2R mAb (300 micrograms/kg/day x10 days i.v., Tx survival about 16 days). In this study, we evaluated intragraft mechanisms responsible for these effects by immunoperoxidase localization of relevant humoral mediators (IgG, IgM, C3, cross-linked fibrin), graft infiltrating cells (GIC), and associated cytokines (IL-2, IFN-g, tumor necrosis factor [TNF], or cytokine receptors (IL-2R). Tx rejected in fulminating fashion by 24 hr in sensitized hosts showed extensive and progressive endothelial deposition of IgG, C3, and fibrin from 2 hr, followed by an influx of neutrophils at 3 hr, and peak numbers of GIC by 18 hr (88.8 +/- 20.3 leukocytes/field). At 18 hr, GIC consisted of neutrophils (26%), T cells (20%, greater than 90% of which were OX-8+), and monocytes/macrophages (53%), whereas B cells were absent. By 18 hr, up to 20% of GIC were IFN-g+, 10% were IL-2R+, and 10% were IL-2+, consistent with labeling of 20% of cells with OX-22. Widespread endothelial and mononuclear cell labeling for TNF and the procoagulant molecular tissue factor (TF) were also noted. In contrast to untreated grafts, CsA treatment essentially abolished intragraft Ig, C3, and fibrin deposition. Moreover, despite dense cell infiltration at 24 hr (total GIC 55.3 +/- 13.4/field), analysis of CsA-treated Tx showed markedly decreased neutrophils (0.5%), with increased T cells (35%) and similar proportions of macrophages (66%). In addition to the reduction in neutrophils, Ig and C3, fewer IL-2R+ (6%) and OX-22+ (3%) cells, considerably less TNF and TF, and almost no IL-2+ or IFN-g+ GIC (less than 1%) were detected. Surprisingly, ART-18 treatment also greatly decreased but did not abolish endothelial deposition of C3, IgG, or IgM, whereas widespread endothelial and mononuclear labeling for fibrin, TNF, and TF remained. In addition, GIC (about 54.8 +/- 16.1/field) contained only moderately reduced numbers of neutrophils (31%) and the proportions of T cells (27%) and macrophages (49%) were generally comparable to those of rejecting Tx in untreated rats.(ABSTRACT TRUNCATED AT 400 WORDS)

Panic disorder among American Indians: a descriptive study

Little is known about panic disorder among American Indians. In a pilot project involving two Northwest Coast Indian villages, community health representatives screened the population for panic disorder, substance abuse, and major depression using DSM-III criteria. Accompanying the screening were subsequent patient education and further evaluation by a psychiatrist, a social worker, and primary care physicians. Of fifty community residents who agreed to take the screening examination, seven were found who met diagnostic criteria for panic disorder. Four of the seven had symptoms of alcohol abuse which complicated the course and diagnosis of panic disorder, and individuals with panic disorder reported more than twice the lifetime prevalence of depression in comparison with other community members. Limitations of the study and refinements of study design are needed in future study discussions.

The effect of diltiazem on coronary flow reserve in humans

Calcium channel antagonists have been shown to blunt maximal coronary flow after brief coronary occlusion and during pharmacologic coronary dilation in animals. This property, if present in humans, would result in a reduction in coronary flow reserve in the absence of intrinsic abnormalities of the coronary circulation. A reduction of maximal vasodilator capacity by calcium channel antagonists could also constitute an important anti-ischemic mechanism of action of these agents. To evaluate the effect of calcium channel antagonists on coronary flow reserve in awake humans, we measured coronary flow reserve using the coronary Doppler catheter and intracoronary papaverine at baseline and after diltiazem administered by intravenous (125 or 250 micrograms/kg bolus, 5 micrograms/kg/min infusion, n = 8) or intracoronary (150-600 micrograms bolus, n = 10) routes. Intravenous diltiazem reduced heart rate from 77 +/- 18 to 72 +/- 17 beats/min (mean +/- SD, p less than 0.005) and reduced mean arterial pressure from 96 +/- 11 to 86 +/- 15 mm Hg (p less than 0.005). Intravenous diltiazem resulted in a small decrease in coronary flow reserve (peak-to-resting flow velocity ratio) from 3.9 +/- 1.2 to 3.6 +/- 1.1 (p less than 0.01). After intracoronary diltiazem, mean arterial pressure was unchanged (control 99 +/- 12 mm Hg, diltiazem 97 +/- 13 mm Hg), and heart rate was maintained constant by atrial pacing. Coronary flow reserve was unchanged at 3.8 +/- 0.9 at baseline and after intracoronary diltiazem. Thus, treatment with diltiazem does not invalidate the measurement of coronary flow reserve for diagnostic purposes. Furthermore, these results suggest that attenuation of maximal coronary dilation by diltiazem is not a mechanism responsible for its antianginal effects.

Results, potential effects, and implementation issues of the Resource-Based Relative Value Scale

This article presents the overall results of the Resource-Based Relative Value Scale (RBRVS) study. We present resource-based relative values for selected services in each of the 18 specialties we studied. We found that preservice and postservice work represents close to 50% of total work for invasive services and 33% of total work for evaluation/management services. We also found that the work per unit time (a measure of intensity) for invasive services is about three times that of evaluation/management. We developed a simple model and simulated an RBRVS-based fee schedule for the Medicare program under a "budget-neutral" assumption. Results for 30 commonly performed services show that office visit fees for evaluation/management services could rise by 70%, while some surgical fees could drop by 60%. We also simulated what the Medicare outlays would have been in 1986 for categories of medical services under an RBRVS-based fee schedule. We found that total Medicare payments for evaluation/management services would have increased by about 56%. Invasive, imaging, and laboratory services would have decreased by 42%, 30%, and 5%, respectively. We also discuss implementation issues related to an RBRVS-based fee schedule, such as the determination of a monetary conversion factor, practice costs, billing codes, and the need to evaluate the potential impacts of an RBRVS-based payment system on the cost and quality of health care.

Extrapolation of measures of work for surveyed services to other services

A national survey of physicians produced detailed data on the work involved in performing 372 different services. This article describes methods developed to extrapolate the study data to a larger universe of services, defined by the Physicians' Current Procedural Terminology, edition 4. Because data measuring work inputs for nonsurveyed services presently are unavailable, we devised an extrapolation method that makes use of available charge data without building their inherent distortions into the extrapolated scale. To neutralize the effect of these distortions, we used small, homogeneous families of services as the basic units for the extrapolations and assumed that charges are reasonable indicators of relative work within such families. To produce extrapolated work values within each family, we multiplied an estimate of work based on survey data for a benchmark procedure by charge-based ratios that represent the relationships between surveyed and nonsurveyed services. These extrapolations can be used in constructing a Resource-Based Relative Value Scale.

Evaluation and management services in the Resource-Based Relative Value Scale

Evaluation and management (E/M) services, which include making diagnoses, counseling and educating, developing strategies of care, and following up on treatment, are common to all medical specialties. Surveys of a variety of specialists using the magnitude-estimation method show that physicians agree closely in rating the work of particular E/M services. Regardless of the type of E/M service, the site at which it is performed, or the specialty performing it, work per unit of time varies only slightly. Comparison of work and time for services to which experts assigned billing codes in our consultative process indicates, however, that there may be large differences in the way different specialties use these billing codes. In some instances, work entailed by some of the E/M billing codes within specialties also appears to vary substantially. If empirical studies of physicians' coding and billing practices support our findings, possible responses might include (1) developing specialty-specific resource-based relative values for E/M services and (2) redefining the Physicians' Current Procedural Terminology, edition 4, codes for these services in terms that include time specifications.

Resource-based relative values. An overview

Studies have been conducted over the past decade to develop a Resource-Based Relative Value Scale (RBRVS) for physicians' services. Policymakers view an RBRVS as a potential tool to pay physicians. The Physician Payment Review Commission, under a congressional mandate, has endorsed the general concept of a fee schedule based on resource costs for physician payment under Medicare. In this overview article, we present the policy context in which the RBRVS may play a role and describe the approach taken to develop this scale, specifically consultation with clinicians, researchers, and insurers and data gathering, including a national survey of physicians. We discuss underlying elements that are necessary to constructing an RBRVS, each of which is described more fully in subsequent articles: measuring the work (intraservice work) of performing medical services and procedures, estimating preservice and postservice work, comparing work across specialties, measuring practice costs, extrapolating from surveyed services, and establishing an RBRVS for evaluation/management services and for invasive procedures. Overall results are presented in a companion article.

A method for estimating the preservice and postservice work of physicians' services

The goal of the Resource-Based Relative Value Scale is to measure the resource costs of physicians' services, or, more centrally, the physicians' total work. This article describes the estimation of relative values for physicians' work before and after the performance of a service (preservice and postservice work). For methodological and practical reasons, we could not obtain direct ratings of preservice and postservice work except for a few services. We therefore developed a systematic process to estimate preservice and postservice time and rate of work per unit of time. Then time and work per unit of time were multiplied to estimate work. The major finding of our investigation is that preservice and postservice work make up a substantial portion of total work. The typical percentages of total work accounted for by preservice and postservice work range from 26% and 33% for imaging services and evaluation and management services, respectively, to 46% for invasive services performed in a hospital inpatient setting.

Measurement and analysis of intraservice work

The work that physicians perform represents a major resource input to medical services and procedures. In this article we describe the concepts of work and its dimensions, as well as the methods developed to measure them. We also describe the design and results of a national probability survey of physicians in 18 specialties. We present the results--estimated values of work and its dimensions--for selected services. Our findings indicate that physicians can give reliable and valid ratings of work and that we can model this work as a function of four dimensions: time, mental effort and judgment, technical skill and physical effort, and stress. Analyzing the complex functional relationship between work and these four dimensions shows that all four dimensions are important and statistically significant in predicting work. Time is a more important dimension in predicting work for medical specialties than for surgical specialties, with the estimated regression coefficients between .3 and .5 and .2 and .3, respectively. In contrast, technical skill is a more important dimension in predicting work in surgical specialties than for medical specialties, with the estimated regression coefficients between .3 and .5 and .2 and .3, respectively. Finally, we found that an exponential equation of the four dimensions precisely describes total work.

Cross-specialty linkage of resource-based relative value scales. Linking specialties by services and procedures of equal work

This article describes methods used to combine into a common scale resource-based relative values from separate specialties. The key to producing a common scale is identifying pairs ("links") of services from different specialties that require approximately equal amounts of intraservice work. We distinguished two kinds of pairs of link services, those judged to be the same and those judged to be equivalent, usually within a narrow category of medical activity. Working with a cross-specialty panel of physicians and with data on time factors from a national survey, we selected sufficient links to connect each specialty to others by at least four links. We then used the weighted least-squares method to locate all the links optimally on a single, common scale. Analyses of the accuracy of this scale showed that the typical disagreement between specialties about where to locate the intraservice work of a given service was only 7%. Other analyses showed that the accuracy of the common scale was not sensitive to different classes of links.

Estimating physicians' work for a resource-based relative-value scale

We have developed a resource-based relative-value scale as an alternative to the system of payment based on charges for physicians' services. Resource inputs by physicians include (1) total work input performed by the physician for each service; (2) practice costs, including malpractice premiums; and (3) the cost of specialty training. These factors were combined to produce a relative-value scale denominated in nonmonetary units. We describe here the process by which the physician's work was defined and estimated. The study asked two questions: What is the physician's work for each service performed? and Can work be estimated reliably and validly? We concluded that a physician's work has four major dimensions: time, mental effort and judgment, technical skill and physical effort, and psychological stress. We found that physicians can rate the relative amount of work of the services within their specialty directly, taking into account all the dimensions of work. Moreover, these ratings are highly reproducible, consistent, and therefore probably valid.

Results and policy implications of the resource-based relative-value study

The resource-based relative-value scale (RBRVS) is a measure of relative levels of resource input expended when physicians produce services and procedures. It is a function of the physician's work input, the opportunity cost of specialty training, and the relative practice costs for each specialty. This paper presents resource-based relative values (RBRVs) for selected procedures of four major specialties--family practice, internal medicine, general surgery, and thoracic and cardiovascular surgery. We compare RBRVs with current charges and find several general patterns. Invasive procedures are typically compensated at more than double the rate of evaluation-and-management services, when both consume the same resource inputs. Imaging and laboratory procedures fall between invasive and evaluation-and-management services. We analyze the financial implications of the RBRVS by developing a simple model and simulating the effects of an RBRVS-based fee schedule on physicians' revenues in various specialties. We use Medicare data to perform the simulation under the "budget-neutral" assumption. Results show that an RBRVS-based fee schedule affects specialties differently. The average family practitioner could receive 60 percent more revenue from Medicare, whereas the average ophthalmologist could lose 40 percent of current revenues. The effects on other specialties fall between these two.

Aluminum-containing emboli in infants treated with extracorporeal membrane oxygenation

We found fibrin thrombi or thromboemboli at autopsy in 22 of 23 infants with respiratory failure who had been treated with venoarterial extracorporeal membrane oxygenation (ECMO). In addition, distinctive basophilic aluminum-containing emboli were found in 12 of the infants; the distribution of these emboli was similar to that of the thromboemboli, except that an aluminum-containing embolus was found in a lung in only 1 infant. Sixteen infants had pulmonary thrombi or thromboemboli. We also found friable aluminum-containing concretions adhering loosely to the mixing rods of heat exchangers that had been used to warm the blood flowing through the ECMO circuit; such concretions were not present on unused mixing rods. We propose that these aluminum-containing concretions developed as the silicone coating of the heat exchanger wore away and aluminum metal was exposed to warm, oxygenated blood and that fragments of aluminum-containing concretions formed emboli. This hypothesis is supported by the fact that aluminum-containing emboli were generally not present in the lungs, which are bypassed by ECMO. Although infarcts were found in 16 of the 23 infants, we cannot be certain whether any of the infarcts were caused by the aluminum-containing emboli.

Neuropsychological improvement following endarterectomy as a function of outcome measure and reconstructed vessel

30 patient receiving right or left carotid reconstruction and 15 medically matched controls were compared pre- and post-surgically on measures of motor speed, sustained vigilance, verbal memory and verbal and nonverbal intellectual function. The group receiving right sided vessel reconstruction demonstrated the largest post-operative improvement in intellectual function in any of the groups. The findings suggest that increased blood perfusion following right sided endarterectomy facilitates the right hemisphere's exclusive control of bilateral attention/arousal responses. In addition, findings suggest that detection of post-endarterectomy improvement may be dependent on the specific task dimension sampled, e.g., speed vs. cognitive ability and verbal-graphic vs. nonverbal symbol manipulation.

[Pulmonary cancerization in juvenile laryngeal papillomatosis]

A case of early onset type of juvenile laryngeal papillomatosis (JLP) is reported, where pulmonary involvement developed in typical aspiration site evidenced by tuberculosis of the right lung, and which stimulated after years a squamous epithelial carcinoma. After comparison of this case with similar cases reported in the literature, the clinical feature of cancerization in JLP is discussed in the context of recent virological, immunohistochemical and pathohistological findings. The infectious nature of this disease and the reparative character of the pathologically accelerated proliferation of the papilloma epithelium are stressed, which latter is thus particularly susceptible to additional noxae: irradiation, cigarette smoke, infection and necrosis. These noxae are considered to be the ultimate cause of cancerization in JLP, especially long-standing necrosis. These noxae are considered to be the ultimate cause of cancerization in JLP, especially long-standing necrotisation of lung structures in pulmonary involvement. Surgical treatment of JLP, eradication being unconceivable, should therefore be rather conservative, and any therapeutic attendance should take utmost care to avoid intrapulmonary seeding.

The Resource-Based Relative Value Scale. Toward the development of an alternative physician payment system

This article describes the design and methods of a study currently under way to develop a Resource-Based Relative Value Scale (RBRVS); an alternative basis for establishing the payment rate for the services and procedures (S/Ps) of physicians in medical and surgical specialties. Physician resource inputs to be measured include (1) S/P time, (2) pre-S/P and post-S/P times, (3) intensity, (4) practice costs, including malpractice premiums, and (5) the cost of specialty training. These five factors will be combined to produce an RBRVS denominated in nonmonetary units. In the initial phase of the study, data on time and intensity will be obtained through a national survey of physicians who perform these S/Ps. In the second, consensus phase of the project, the investigators will convene a panel of representatives of the medical profession, third-party payers, consumers, and other interested parties to examine areas of agreement and disagreement as to how an RBRVS should be used for policy purposes. The final results of this study are expected by the summer of 1988.

Molecular cloning and primary structure of myelin-associated glycoprotein

Myelin-associated glycoprotein (MAG) may play a role in the cellular interactions leading to myelination. Using monoclonal antibodies and conventional antisera against MAG, we have isolated a cDNA clone from an expression library prepared from rat brain mRNA. The identity of the clone was confirmed by the exact match between its nucleotide sequence and two peptide sequences of 13 and 9 amino acids that we obtained by Edman degradation of two CNBr fragments of MAG. The cDNA clone hybridized to two size species of mRNA in rat approximately 3.5 kilobases in length. These mRNAs were present in brain but not liver and were expressed most abundantly at the time of active myelination (day 14). The mRNA for MAG was present at barely detectable levels in hypomyelinating jimpy mice compared to normal littermate controls. Therefore the MAG cDNA clone is both brain and myelin specific. DNA sequence analysis revealed that our MAG cDNA was derived from the same mRNA as clone p1B236, a randomly selected, brain-specific, partial cDNA isolated by Sutcliffe et al. [Sutcliffe, J. G., Milner, R. J., Shinnick, T. M. & Bloom, F. E. (1983) Cell 33, 671-682]. Analysis of the predicted protein sequence suggests that MAG has a long extracellular domain (499 amino acids), followed by a short transmembrane segment (20 amino acids) and an intracellular carboxyl-terminal domain (90 amino acids). The molecule has several glycosylation sites, three internal repeats homologous to a repeat in the neural cell adhesion molecule (N-CAM), and sites for phosphorylation near the carboxyl terminus. The primary structure reported here provides a molecular framework for further investigations into the function of the MAG molecule.

Extracorporeal membrane oxygenation for postoperative cardiac support in children

Prolonged circulatory support for cardiac failure has been increasingly successful in adults but has had very limited use in children. From January 1982 to December 1985, 13 children with postoperative cardiac failure refractory to conventional therapy were treated with extracorporeal membrane oxygenation. Ages ranged from 9 days to 17.6 years (mean = 3.8 years); weights ranged from 2.8 to 50 kg (mean = 13.8 kg). Seven patients had obstructive lesions of the right ventricle, such as pulmonary stenosis and tetralogy; the other patients had tricuspid atresia, truncus arteriosus, complete transposition, total anomalous pulmonary venous connection, pericardial tamponade, and a drug reaction after heart transplantation. One patient (nonsurvivor), who could not be separated from cardiopulmonary bypass, required extracorporeal membrane oxygenation in the operating room. In the remaining 12, the interval between operation and the start of extracorporeal membrane oxygenation ranged from 9 to 50 hours (mean = 22.2 hours). Four patients were cannulated through the groin and nine through the chest. Peak flows ranged from 1.05 to 2.74 L/min/m2 (mean 1.92 L/min/m2). Duration of oxygenator support ranged from 12 hours to 9 days (mean = 3.4 days). Seven patients required reexploration for bleeding. Renal insufficiency developed in five patients, four of whom underwent hemodialysis or ultrafiltration during extracorporeal membrane oxygenation. Two patients had evidence of clots in the oxygenator circuit. Seven patients were weaned from extracorporeal membrane oxygenation. Failure to wean from the oxygenator was related to neurologic sequelae of prolonged hypotension before institution of oxygenation in three patients. Mediastinitis developed in three of the seven patients who were weaned. One of these three died in the hospital 74 days after being weaned from the oxygenator. There has been one late death 6 months after oxygenator support was withdrawn. At most recent examination, five children were well, with normal cardiac function 7 months to 4.3 years postoperatively (mean = 32 months). This series suggests that profound cardiac insufficiency in children after cardiac operations can be successfully managed with extracorporeal membrane oxygenation with excellent functional recovery, although major complications are common in this critically ill group of patients.

Extracorporeal membrane oxygenation for newborn respiratory failure

Jugular vein-carotid artery extracorporeal membrane oxygenation (ECMO) was utilized in 22 newborns (16 male and 6 female) 1 to 12 days old with respiratory failure due to meconium aspiration (12 patients), diaphragmatic hernia (4), persistent fetal circulation (3), hyaline membrane disease (2), and Rh incompatibility (1). Prior to ECMO, all patients had alveolar-arterial O2 pressure gradients greater than 580 mm Hg (predicted mortality greater than 90%), weighed more than 1,800 gm, had a gestation period of longer than 35 weeks, and had no cerebral hemorrhage. The duration of ECMO was 41 to 310 hours (mean, 134.5 hours). Nineteen (86%) of the 22 patients survived ECMO. Death was caused by lung disease (2) and cerebral hemorrhage (1). Four other patients died 6 to 40 days after ECMO of pulmonary hypoplasia (1), pneumonia (1), cerebral edema (1), and hepatorenal failure (1). Complications during ECMO were few and easily managed. Fifteen infants (68%) are alive 1 to 18 months after ECMO. Three have neurological deficit (2 severe, 1 mild). Bayley Developmental Examinations in 4 survivors now more than 12 months old are normal. Extracorporeal membrane oxygenation is an aggressive but effective technique of life support in newborns refractory to conventional respiratory management. Potential complications of ECMO mandate strict aseptic technique, constant monitoring, and multidisciplinary patient management.

Elective hysterectomy. Benefits, risks, and costs

This study evaluated the effect of hysterectomy or hysterectomy and bilateral salpingo-oophorectomy (hysterectomy and oophorectomy) versus alternative medical management on life expectancy, quality of life, and direct medical costs. Using techniques of decision analysis and available data on sequelae, it was found that gains in life expectancy and quality of life can be expected when women ages 30-60 undergo hysterectomy for benign neoplasm, disorders of menstruation, acquired abnormal anatomy, cervical disease, or endometriosis, owing primarily to prevention of reproductive tract cancers, which outweighs the impact of operative mortality. However, women who have relatively high operative risk or low expected cancer risks, beyond thresholds estimated in sensitivity analyses, suffer losses in life expectancy. Women younger than 35 not treated with replacement estrogens following hysterectomy and oophorectomy can expect net losses in life expectancy with surgical intervention due to increased risks of heart disease and osteoporosis. For women in the reproductive years who wish to preserve their potential to bear children, sterilization may be an unacceptable consequence of elective hysterectomy in the quality of life.

Probabilistic sensitivity analysis using Monte Carlo simulation. A practical approach

The data for medical decision analyses are often unreliable. Traditional sensitivity analysis--varying one or more probability or utility estimates from baseline values to see if the optimal strategy changes--is cumbersome if more than two values are allowed to vary concurrently. This paper describes a practical method for probabilistic sensitivity analysis, in which uncertainties in all values are considered simultaneously. The uncertainty in each probability and utility is assumed to possess a probability distribution. For ease of application we have used a parametric model that permits each distribution to be specified by two values: the baseline estimate and a bound (upper or lower) of the 95 percent confidence interval. Following multiple simulations of the decision tree in which each probability and utility is randomly assigned a value within its distribution, the following results are recorded: (a) the mean and standard deviation of the expected utility of each strategy; (b) the frequency with which each strategy is optimal; (c) the frequency with which each strategy "buys" or "costs" a specified amount of utility relative to the remaining strategies. As illustrated by an application to a previously published decision analysis, this technique is easy to use and can be a valuable addition to the armamentarium of the decision analyst.

Classification of dementia patients by a WAIS profile related to central cholinergic deficiencies

Sixty-two patients were classified as having Alzheimer-type dementia (AD) or multi-infarct dementia (MID) on the basis of clinical criteria. Protocols from the Wechsler Adult Intelligence Scale (WAIS) were scored according to a formula reported by Fuld to reflect the effects of scopolamine administration in young adults. The formula correctly classified 13 of 23 AD patients and 37 of 39 MID patients. The formula was similar to Wechsler's deterioration quotient, which produced a greater number of false positives. The formula did not appear to be biased by age, sex, or severity of impairments. Results suggest that the neuropsychological investigation of AD which emphasizes the deficiencies in cholinergic neurotransmission may be a fruitful avenue of further investigation.

The influence of brassinosteroid on growth and parameters of photosynthesis of wheat and mustard plants

The growth response of wheat (Triticum aest. L.) and mustard seedlings (Sinapis alba L.) treated with 10(-6) mol · l(-1) brassinosteroid (BR) foliar spray was measured. BR-treatment resulted in a general promotion of plant growth. We found the accumulation of photosynthates to be stimulated in the treated plants, as indicated by enhanced fresh and dry weights of leaves and shoots. BR also promoted the synthesis of soluble proteins and soluble reducing sugars, whereas the chlorophyll content was hardly affected. CO(2)-fixation in vivo as well as the (in vitro) RubPC-ase activity of BR-treated leaves were enhanced. In the developing wheat leaves we detected no difference in the ratio fraction-I-protein (F-I-P)/total soluble protein between BR-treated and control plants whereas in the expanded leaves this ratio was lowered under BR-treatment.

Gonorrhea case-finding among asymptomatic men seeking ambulatory care: a cost effectiveness analysis

Case-finding for gonorrhea in asymptomatic men is generally not performed in primary care settings and often not performed when men are seen for other reasons in clinics for sexually transmitted diseases. We performed a cost-effectiveness analysis of case-finding among asymptomatic men seeking ambulatory care, using culture of the first-voided urine and treatment of culture-positive patients with tetracycline. The analysis demonstrated that care-finding is increasingly cost-effective as the probability of asymptomatic gonorrhea becomes greater. Over a reasonable expected range of the probability of asymptomatic gonorrhea (0.1-15%) in such settings, the additional cost to avert one additional day of morbidity ranged from $47,000 to $260; the additional cost to avert one additional case of residual asymptomatic infection ranged from $26,000 to $140; and the additional cost to avert one additional case of pelvic inflammatory disease in a contact ranged from $250,000 to $1,400. We conclude that the cost-effectiveness of case-finding for gonorrhea among asymptomatic men compares favorably with that of other medical interventions when the probability of infection is relatively high (perhaps greater than or equal to 5%). In order to make use of such information, physicians in ambulatory care settings require better information about the probability of gonorrhea in asymptomatic men who differ in their medical histories and socioeconomic and ethnic backgrounds.

Neuropsychological performance one week after carotid endarterectomy reflects intra-operative ischemia

Fourteen patients with severe bilateral carotid artery stenosis underwent carotid endarterectomy. Intra-operative ischemia was monitored by somatosensory evoked potentials (SSEP) bilaterally. Neuropsychological evaluations were completed within two days before operation and 4-9 days after operation. Complete loss of N1-P1 or P1-N2 components of the SSEP (seen in 4 patients) was associated with a worsening of neuropsychological abilities (p less than .01). Two of these patients subsequently had strokes (7 and 35 days after operation). No other patients in the series have had strokes. Patients whose N1-P1 or P1-N2 amplitudes decreased by 50% or more performed worse after operation than patients with less severe reductions in these amplitudes (p less than .02). Time since first ischemic symptoms, age, education, clamp time, pre-operative stroke, and interval from surgery to assessment were not statistically related to changes in neuropsychological abilities. Patients with ischemic events in the week prior to surgery tended to improve in neuropsychological abilities 4-9 days after operation (p less than .05). Recentness of ischemic episode, however, was not related to intra-operative SSEP change. Results suggest the potential utility of intra-operative SSEP monitoring and early post-operative neuropsychological assessments both for clinical and research purposes.