Testosterone metabolism of equine single CYPs of the 3A subfamily compared to the human CYP3A4.

Cytochrome P450 enzymes (CYPs) are responsible for the phase I metabolism of drugs, xenobiotics and endogenous substances. Knowledge of single CYPs and their substrates is important for drug metabolism, helps to predict adverse effects and may prevent reduced drug efficacy in polypharmacy. In this study, three equine isoenzymes of the 3A subfamily, the equine flavoprotein NADPH-P450 oxidoreductase (POR), and the cytochrome b5 (CYB5) were cloned, sequenced and heterologously expressed in a baculovirus expression system. Testosterone, the standard compound for characterization of the human CYP3A4, was used to characterize the newly expressed equine CYPs. The metabolite pattern was similar in equine and the human CYPs, but the amounts of metabolites were isoform-dependent. All equine CYPs produced 2-hydroxytestosterone (2-OH-TES), a metabolite never described in equines. The main metabolite of CYP3A4 6ß-hydroxytestosterone (6ß-OH-TES) was measured in CYPs 3A95 and 3A97 with levels close to the detection limit. Ketoconazole inhibited 2-OH-TES in the human CYP3A4 and the equine CYP3A94 and CYP3A97 completely, whereas a 70% inhibition was found in CYP3A95. Testosterone 6ß- and 2-hydroxylation was significantly different in the equine CYPs compared to CYP3A4. The expression of single equine CYPs allows characterizing drug metabolism and may allow prevention of drug-drug interactions.

Sellado marginal en restauraciones indirectas, cementadas con dos sistemas adhesivos diferentes / Marginal sealing in indirect restorations, cemented with two different adhesive systems

Propósito: El propósito de esta investigación fue realizar un estudio in vitro del sellado marginal de 80 incrustaciones de resina compuesta cementadas con resina compuesta fluida utilizando un sistema adhesivo autograbante (Go!, SDI, Australia) y un sistema adhesivo con grabado ácido total (Stae, SDI, Australia). Método: Las piezas dentarias restauradas fueron puestas en una estufa a 37ºC y 100 por ciento de humedad relativa durante 48 horas para simular las condiciones bucales. Luego fueron sometidas a termociclado, en una solución de azul de metileno al 1 por ciento. Posteriormente las muestras fueron cortadas en sentido vestíbulo lingual o palatino, para ser observadas bajo un microscopio óptico, para evaluar la interfase diente restauración midiendo los porcentajes de filtración para ambos grupos. Resultados: Los resultados fueron analizados estadísticamente mediante el t-test de Student obteniéndose diferencias significativas entre los dos grupos estudiados. Conclusión: Todos los cuerpos de prueba presentaron algún grado de filtración marginal, sin embargo el grupo que utilizó un sistema adhesivo autograbante demostró tener valores significativamente mayores de filtración que el grupo que utilizó el sistema convencional.

Aim: The purpose of this research was to study the marginal sealing in 80 composite resin inlay, bonded with flow composite resin using a Self-etch fluid (Go!, SDI, Australia) versus a total-etching system (Stae, SDI, Australia). Method: The samples were placed in an oven at 37ºC and 100 percent humidity for 48 hours, after which the samples were thermocycled in a methylene blue 1 percent solution. This cycle was repeated 80 times. The samples were cut transversally, the restorations were observed trough an optical microscope to calculate the percentage of filtration in relation to the total length of the cavity to the axial wall. Results: The results were statistically analyzed by Student t-test. And there were significant differences in the marginal leakage. The group that used a Self-etch adhesive system showed significantly higher marginal leakage values than the group that used the conventional system. Conclusion: All the samples showed some degree of marginal leakage, but the group using a self-etching adhesive system showed marginal leakage values significantly higher than the group using the conventional one.

Information access at the point of care: what can we learn for designing a mobile CPR system?

OBJECTIVES: Hospitals have started to migrate their paper-based records to computerized patient records (CPR). The majority of today's CPR systems are stationary, which means that physicians use a clinical workstation to access CPR information. But health care professionals need to request and enter information at different locations, for example, on their daily ward round. This suggests the use of mobile computers, enabling an ubiquitous access to needed data. Different studies show that health care professionals are reluctant to use poorly designed mobile CPR systems, as the work at the point of care is very time-pressured and hectic. To design a system with high acceptance, it is essential to obtain empirical insight into the work practices and context in which the mobile CPR system will be used. METHOD: We investigated the physicians' work with the patient record during their daily round. With the help of a compact notation method, the physicians' interaction with the information system was recorded in real time. Fourteen physicians from three different departments (internal medicine, surgery, and geriatrics) of a middle-sized Swiss hospital participated in our study. RESULTS: Physicians have clear access preferences when they interact with the patient record during their daily round. There exists a clear profile of access frequencies and patterns, respectively. As an example, approximately 50% of all patient record accesses concern information about medications, vital signs and lab test results. DISCUSSION/CONCLUSION: A CPR system which is designed to reflect the access frequencies and patterns should improve the efficiency of data entry and retrieval and thus result in a system with high acceptance among physicians in the demanding environment during hospital rounds.

Assessment of myocardial perfusion in coronary artery disease by magnetic resonance: a comparison with positron emission tomography and coronary angiography.

BACKGROUND: Monitoring contrast medium wash-in kinetics in hyperemic myocardium by magnetic resonance (MR) allows for the detection of stenosed coronary arteries. In this prospective study, the quality of a multislice MR approach with respect to the detection and sizing of compromised myocardium was determined and compared with positron emission tomography (PET) and quantitative coronary angiography. METHODS AND RESULTS: A total of 48 patients and healthy subjects were studied by MR using a multislice hybrid echo-planar pulse sequence for monitoring the myocardial first pass kinetics of gadolinium-diethylenetriamine pentaacetic acid bismethylamide (Omniscan; 0.1 mmol/kg injected at 3 mL/s IV) during hyperemia (dipyridamole 0.56 mg/kg). Signal intensity upslope as a measure of myocardial perfusion was calculated in 32 sectors per heart from pixelwise parametric maps in the subendocardial layer and for full wall thickness. Before coronary angiography, coronary flow reserve (hyperemia induced by dipyridamole 0.56 mg/kg) was determined in corresponding sectors by (13)N-ammonia PET. Receiver-operator characteristic analysis of subendocardial upslope data revealed a sensitivity and specificity of 91% and 94%, respectively, for the detection of coronary artery disease as defined by PET (mean coronary flow reserve minus 2SD of controls) and a sensitivity and specificity of 87% and 85%, respectively, in comparison with quantitative coronary angiography (diameter stenosis >/=50%). The number of pathological sectors per patient on PET and MR studies correlated linearly (slope, 0.94; r=0.76; P<0.0001). CONCLUSIONS: The presented MR approach reliably identifies patients with coronary artery stenoses and provides information on the amount of compromised myocardium, even when perfusion abnormalities are confined to the subendocardial layer. This modality may qualify for its clinical application in the management of coronary artery disease.

[Cervical tuberculous lymphadenitis--an up-to-date guideline for management]. / Halslymphknotentuberkulose: aktuelles Abklärungs- und Behandlungskonzept.

For the past two decades the incidence of tuberculosis has been increasing, especially in developed countries. This is due to immigration from endemic countries, newly developed drug resistance, poor hygienic conditions for citizens of low socioeconomic status, and the spread of HIV-related immunodeficiency. Cervical tuberculous lymphadenitis is the most common form of extrapulmonary tuberculosis. In relation to the patients' age and immunocompetence, it is caused by typical or atypical mycobacteria. Within a period of 2 1/2 years we have treated 6 patients for mycobacterial infections in our department. We present an up-to-date guideline for management based on this experience. It combines well established diagnostic management with new criteria of ultrasonography, fine needle aspiration and mycobacterial cultures.

Optimized performance of the Abiomed BVS 5000: adjustment of the pump height based on Doppler control of the flow pattern.

The Abiomed BVS 5000 is an automatic volume-driven paracorporeal pulsatile assist device providing left, right or biventricular support. The paracorporeal position allows optical adjustment of filling volumes of the device, which determines the output of the system. A procedure to adjust for maximal stable flow has not yet been established. In vitro measurements have been performed to assess the flow and pressure characteristics of the Abiomed BVS 5000 by raising the preload in 5 mmHg steps before running the system. Doppler probes were placed at the inflow and outflow lines of the pump. After setting the afterload at 80 mmHg the assist device was started. Two measurements were performed to find optimal flow (based on Doppler control and optical adjustment). (1) By Doppler control a stable flow pattern was found at a preload of 25 mmHg with a mean atrial pressure of 5 mmHg and a mean flow of 5.3 +/- 0.7 l/min (mean +/- standard deviation) at the inflow and outflow sites (the console flow was 4.8 +/- 0.4 l/min with a frequency of 61.8 +/- 2.0 l/min). (2) Optical adjustment of the pump height gave rise to a preload of 35 mmHg where we recorded a maximal atrial pressure of 107 +/- 5.8 mmHg, a maximal retrograde flow of -4.3 +/- 1.2 l/min at the inflow and -1.2 +/- 0.4 l/min at the outflow site. The mean flow at the inflow and outflow sites was 5.1 +/- 0.5 l/min (the console flow was 4.6 +/- 0.3 l/min with a frequency of 59.6 +/- 2.6 Hz). At an initial afterload of 60 and 40 mmHg the system showed the same qualitative behaviour, but the results were less accurate. Optical adjustment of the pump height may result in an atrioventricular valve insufficiency with undetected retrograde flow and high atrial pressures. We conclude that a Doppler flow probe must be placed at the inflow site to guarantee maximal stable flow.

Impact of Doppler guidewire size and flow rates on intravascular velocity profiles.

Coronary blood flow velocity measurements by conventional intravascular catheter-based Doppler devices are well known to be affected by catheter size. Moreover, it is of clinical importance that the assessment of maximum vasodilator capacity, i.e., the coronary reserve, might be considerably affected by a shape change of the velocity profile under hyperemia. Therefore, the present in vitro study aimed to assess the impact of a small-size Doppler guidewire on the velocity profiles interrogated in tubes with diameters corresponding to the epicardial coronary arteries at clinically relevant flow rates. A 0.014" guidewire was inserted into four serially connected silicone tubes of known diameter, which were perfused with discarded human whole blood by means of a roller pump. In order to determine the effect of the Doppler guidewire on the velocity profile antegrade and retrograde perfusion were carried out in each vessel segment. Vm, the true mean velocity, was calculated from the time collected flow divided by the corresponding vessel cross-sectional area. Average peak velocity (APV) measurements were obtained by pulling back the Doppler device across each of the four vessel segments with given flow rates ranging from 1.14-5.88 ml/s in antegrade and retrograde direction. The shape factor of the recorded velocity profile (fp) is defined as vm/APV and is generally assumed to be close to 0.5. Antegrade perfusion: APV = 1.63 vm + 5.35 (R2 = 0.98); fp = 0.001 vm + 0.51. Retrograde perfusion: APV = 1.71 vm + 3.33 (R2 = 0.98); fp = 0.001 vm + 0.52. Due to the constant relationship between APV and vm, velocity profiles within vessels of epicardial coronary artery size are not substantially disturbed by the presence of the Doppler guidewire. The slight, but significant increase of experimental fp with increasing flow is at variance with the theoretically expected fp values.

Position control of intravascular Doppler guidewire: concept of a tracking indicator and its clinical implications.

Intracoronary Doppler ultrasound guidewires (DGW) utilize a wide ultrasound beam combined with a measurement of the spectral peak velocity to estimate the spatial peak velocity within a blood vessel. However, the spectral peak velocity may underestimate the true spatial peak velocity if the DGW is not properly positioned. The purpose of this study was to find a Doppler-derived parameter that would aid in the optimal positioning of the DGW within the vessel lumen. We studied the relationship between the time-averaged, spectral-peak velocity (APV) and the normalized first Doppler moment (M1/M0) to develop a DGW position indicator and demonstrate its clinical utility. In vitro, heparinized, human whole blood with a hematocrit of 45% was directed from a reservoir via a roller pump into four serially connected straight silicone tubes of known diameter (2.5, 3.0, 3.5, 4.0 mm). A DGW was inserted into the tubes where simultaneous APV and M1/M0 measurements were obtained for flow rates ranging from 49 to 316 ml/min. Optimal positioning of the DGW was identified at the position where maximum APV and M1/M0 were obtained. With optimal positioning the correlation between APV and M1/M0 was good (APV = 1.62 M1/M0 + 5.0; R2 = 0.98). Importantly, this correlation showed no dependence on the tube diameter. In vivo, in four patients APV and M1/M0 measurements were obtained in 16 coronary artery segments in one left anterior descending, two circumflex, and two right coronary arteries. In 10 vessel segments, there was no discrepancy between the measured and expected M1/M0 after positioning the DGW with help of the Doppler signal quality only. In six vessel segments, repeat DGW positioning using M1/M0 was necessary, yielding an average increase of APV of 20% (7-38%). We conclude that DGW positioning can be optimized using the correlation between APV and M1/M0 as a reference. For any given APV value, there is a corresponding expected value for M1/M0 under the condition of optimal positioning. Any discrepancy between the measured and expected values for M1/M0 then indicates suboptimal positioning.

Measurement of flow velocity in the coronary circulation: requirements and pitfalls.

The introduction of Doppler guide wires has allowed the wide-spread use of Doppler technology in the catheterization laboratory for coronary diagnostics and pathophysiological studies. Doppler-ultrasound-derived measurement of coronary flow velocity serves as a substitute for true volumetric flow measurement. To produce reliable and reproducible flow velocity data, the whole Doppler spectrum should be evaluated. Special attention should be paid to the velocity distribution within the spectrum. A spectral display with strong signals in the high velocity range and a sharply defined envelope are markers for a good positioning of the Doppler wire. Additional security for the optimal positioning can give the recently developed tracking indicator. For reliable CFR determination using average peak velocity at rest and during hyperaemia, changes of the shape of the velocity profile and of the cross-sectional vessel area, as well as the position of the Doppler guide wire, have to be taken into account, otherwise the CFR will be underestimated. To eliminate cross-sectional area changes, the vessel should be pretreated with nitroglycerin.

Improved stenosis geometry by quantitative coronary arteriography after vigorous risk factor modification.

This study is a randomized, controlled, blinded, arteriographic trial to determine the effects of a low-cholesterol, low-fat, vegetarian diet, stress management and moderate aerobic exercise on geometric dimensions, shape and fluid dynamic characteristics of coronary artery stenoses in humans. Complex changes of different primary stenosis dimensions in opposite directions or to different degrees cause stenosis shape change with profound effects on fluid dynamic severity, not accounted for by simple percent narrowing. Accordingly, all stenosis dimensions were analyzed, including proximal, minimal, distal diameter, integrated length, exit angles and exit effects, determining stenosis shape and a single integrated measure of stenosis severity, stenosis flow reserve reflecting functional severity. In the control group, complex shape change and a stenosis-molding characteristic of statistically significant progressing severity occurred with worsening of stenosis flow reserve. In the treated group, complex shape change and stenosis molding characteristic of significant regressing severity was observed with improved stenosis flow reserve, thereby documenting the multidimensional characteristics of regressing coronary artery disease in humans.

Left ventricular wall stress distribution in chronic pressure and volume overload: effect of normal and depressed contractility on regional stress-velocity relations.

Regional stress-velocity relations were determined in a first group of patients (n = 15) with normal (five controls, five patients with aortic stenosis, and five patients with aortic insufficiency) and a second group of patients (n = 10) with depressed contractility (five patients with aortic stenosis and five with aortic insufficiency). LV circumferential wall stress was calculated from high-fidelity pressure and frame-by-frame angiocardiographic data using the Wong thick-wall model. Regional wall stress and shortening velocity were calculated from the endo- to the epicardium, and from the equator to the apex at 35 points. Regional LV wall stress was in all patients lower at the epi- than the endocardium, and lower at the apex than the equator. Regional stress-velocity relations were downward shifted from the endo- to the epicardium and from the equator to the apex (family of curves) in both groups. At corresponding LV regions stress-velocity relations showed significantly smaller slopes and intercepts (downward depression) in group 2 than in group 1. Thus, wall stress distribution is inhomogeneous in the normal, as well as in the pressure and volume overloaded left ventricle. Regional differences in stress-velocity relations within groups (family of curves) are probably related to changes in preload rather than to changes in regional contractility. Downward depression of the regional stress-velocity relations in group 2 is caused by depressed myocardial contractility.

Potential role of coronary vasoconstriction in ischaemic heart disease: effect of exercise.

Coronary vasomotion plays an important role in the regulation of coronary perfusion at rest and during exercise. Normal coronary arteries show coronary vasodilation of the proximal (+20%) and distal (+40%) vessel segments during supine bicycle exercise. However, patients with coronary artery disease show exercise-induced vasoconstriction of the stenotic vessel segments. The exact mechanism of exercise-induced stenosis narrowing is not clear but might be related to a passive collapse of the disease-free vessel wall (Venturi mechanism), elevated plasma levels of circulating catecholamines, an insufficient production of the endothelium-derived vasorelaxing factor or increased platelet aggregation due to turbulent blood flow with release of thromboxane A2 and serotonin. Various vasoactive drugs, such as nitroglycerin and calcium antagonists, prevent exercise-induced stenosis vasoconstriction. An additive effect on coronary vasodilation of the stenotic vessel segment was observed after combination of nitroglycerin with diltiazem. Thus, exercise-induced stenosis narrowing plays an important role in the pathophysiology of myocardial ischaemia during dynamic exercise. The antianginal effect of vasoactive substances can be explained--besides the effect on pre- and afterload--by a direct action on coronary stenosis vasomotion.

Coronary flow reserve as a physiologic measure of stenosis severity.

PART I: Coronary flow reserve indicates functional stenosis severity, but may be altered by physiologic conditions unrelated to stenosis geometry. To assess the effects of changing physiologic conditions on coronary flow reserve, aortic pressure and heart rate-blood pressure (rate-pressure) product were altered by phenylephrine and nitroprusside in 11 dogs. There was a total of 366 measurements, 26 without and 340 with acute stenoses of the left circumflex artery by a calibrated stenoser, providing percent area stenosis with flow reserve measured by flow meter after the administration of intracoronary adenosine. Absolute coronary flow reserve (maximal flow/rest flow) with no stenosis was 5.9 +/- 1.5 (1 SD) at control study, 7.0 +/- 2.2 after phenylephrine and 4.6 +/- 2.0 after nitroprusside, ranging from 2.0 to 12.1 depending on aortic pressure and rate-pressure product. However, relative coronary flow reserve (maximal flow with stenosis/normal maximal flow without stenosis) was independent of aortic pressure and rate-pressure product. Over the range of aortic pressures and rate-pressure products, the size of 1 SD expressed as a percent of mean absolute coronary flow reserve was +/- 43% without stenosis, and for each category of stenosis severity from 0 to 100% narrowing, it averaged +/- 45% compared with +/- 17% for relative coronary flow reserve. For example, for a 65% stenosis, absolute flow reserve was 5.2 +/- 1.7 (+/- 33% variation), whereas relative flow reserve was 0.9 +/- 0.09 (+/- 10% variation), where 1.0 is normal. Therefore, absolute coronary flow reserve by flow meter was highly variable for fixed stenoses depending on aortic pressure and rate-pressure product, whereas relative flow reserve more accurately and specifically described stenosis severity independent of physiologic conditions. Together, absolute and relative coronary flow reserve provide a more complete description of physiologic stenosis severity than either does alone. PART II: Coronary flow reserve directly measured by a flow meter is altered not only by stenosis, but also by physiologic variables. Stenosis flow reserve is derived from length, percent stenosis, absolute diameters and shape by quantitative coronary arteriography using standardized physiologic conditions. To study the relative merits of absolute coronary flow reserve measured by flow meter and stenosis flow reserve determined by quantitative coronary arteriography for assessing stenosis severity, aortic pressure and rate-pressure product were altered by phenylephrine and nitroprusside in 11 dogs, with 366 stenoses of the left circumflex artery by a calibrated stenoser providing percent area stenosis as described in Part I.(ABSTRACT TRUNCATED AT 400 WORDS)

Coronary artery-right ventricular fistula in a heart transplant patient.

Routine coronary angiography 2 years after heart transplantation in a 48-year-old patient revealed a fistula from a septal branch of the left anterior descending artery to the right ventricle. This finding was not present at coronary angiography 1 year before. This coronary-ventricular fistula is most probably the result of repeated endomyocardial biopsies.

Validation of a new automatic system for biplane quantitative coronary arteriography.

In a collaboration between the University of Texas (software) and the University of Zürich (hardware) a compact, automatic system for biplane quantitative coronary arteriography was developed. The system is based on a 35 mm film projector, a slow-scan CCD-camera (image digitizing) and a computer workstation (Apollo DN 3000, image storage and processing). A new calibration procedure based on two fixed reference points in the center of the image intensifier was used (isocenter technique). Contour detection of coronary arteries was carried out in biplane projection using a geometric-densitometric edge-detection algorithm. The proximal and distal luminal areas, as well as the minimal luminal area of the stenotic vessel segment were determined. Accuracy and precision were determined from precision drilled holes in a plexiglas cube which were filled with 50%, 75% and 100% contrast medium. The diameter of the holes ranged from 0.5 to 5.0 mm. The mean difference and the standard deviation of the differences between the true and the measured diameters were 0.12 +/- 0.14 mm for plane A and 0.26 +/- 0.17 mm for plane B, respectively. After a second order correction the mean difference amounted to 0.02 +/- 0.09 mm for plane A and 0.02 +/- 0.12 mm for plane B, respectively. Intra- and interobserver variability were evaluated in 5 patients (age 60 +/- 10 years) with coronary artery disease using 16 normal and 5 stenotic vessel segments (cross-sectional area ranging from 0.8 to 8.7 mm2). Two independent observers analyzed the same vessel segment twice. Intraobserver variability expressed as the standard error of estimate in percent of the mean angiographic vessel area (SEE) amounted to 2.1% for observer 1 and 4.4% for observer 2, respectively. Interobserver variability expressed as SEE was 4.1% for measurement 1 and 3.6% for measurement 2, respectively.

The use of pressure-volume curves to assess the mechanism and adequacy of stenosis dilatation by balloon angioplasty.

This report introduces a new technique for monitoring and understanding the mechanical events taking place during coronary balloon angioplasty. A standard inflation syringe is instrumented with transducers to record intra-balloon pressure and volume during stenosis dilatation. The theoretical and practical aspects of obtaining and interpreting PTCA "pressure-volume" curves are described. Based on mechanical principles, this method may provide the PTCA operator with information regarding the stiffness and resilience of each stenosis, the mechanism of dilatation, and a measure of adequacy of lumen enlargement even before the balloon is deflated.