Growth of textured thin Au coatings on iron oxide nanoparticles with near infrared absorbance.

A homologous series of Au coated iron oxide nanoparticles with hydrodynamic diameters smaller than 60 nm was synthesized with very low Au-to-iron mass ratios, as low as 0.15. The hydrodynamic diameter was determined by dynamic light scattering and the composition by atomic absorption spectroscopy and energy dispersive x-ray spectroscopy. Unusually low Au precursor supersaturation levels were utilized to nucleate and grow Au coatings on iron oxide relative to the formation of pure Au nanoparticles. This approach produced unusually thin coatings by lowering autocatalytic growth of Au on Au, as shown by transmission electron microscopy. Nearly all of the nanoparticles were attracted by a magnet, indicating a minimal number of pure Au particles. The coatings were sufficiently thin to shift the surface plasmon resonance to the near infrared with large extinction coefficients, despite the small particle hydrodynamic diameters observed from dynamic light scattering to be less than 60 nm.

Diastolic dysfunction in hypertrophic cardiomyopathy. Effect on active force generation during systole.

We tested the hypothesis that intracellular Ca++ [( Ca++]i) overload underlies the diastolic dysfunction of patients with hypertrophic cardiomyopathy. Myocardial tissue was obtained at the time of surgery or transplantation from patients with hypertrophic cardiomyopathy and was compared with control myocardium obtained from patients without heart disease. The isometric contractions and electrophysiologic properties of all myocardial specimens were recorded by standard techniques and [Ca++]i was measured with the bioluminescent calcium indicator aequorin. In contrast to the controls, action potentials, Ca++ transients, and isometric contraction and relaxation were markedly prolonged in the hypertrophic myocardium, and the Ca++ transients consisted of two distinct components. At 38 degrees C and 1 Hz pacing frequency, a state of relative Ca++ overload appeared develop, which produced a rise in end-diastolic [Ca++]i, incomplete relaxation, and fusion of twitches with a resultant decrease in active tension development. We also found that drugs with increase [Ca++]i, such as digitalis, exacerbated these abnormalities, whereas drugs that lower [Ca++]i, such as verapamil, or agents that increase cyclic AMP, such as forskolin, prevented them. These results may explain why patients with hypertrophic cardiomyopathy tolerate tachycardia poorly, and may have important implications with regard to the pharmacologic treatment of patients with hypertrophic cardiomyopathy.

Depression of systolic and diastolic myocardial reserve during atrial pacing tachycardia in patients with dilated cardiomyopathy.

Previous reports have shown that increases in heart rate may result in enhanced left ventricular (LV) systolic and diastolic performance. To assess whether this phenomenon occurs in the presence of depressed LV function, the effects of pacing on LV pressure and volume were compared in seven patients with dilated cardiomyopathy (LV ejection fraction 0.19 +/- 0.11) and six patients with no or minimal coronary artery disease (LV ejection fraction 0.69 +/- 0.11). Patients with normal LV function demonstrated significant increases in LV peak-positive dP/dt, LV end-systolic pressure-volume ratio, LV peak filling rate, and a progressive leftward and downward shift of their pressure-volume diagrams, compatible with increased contractility and distensibility in response to pacing tachycardia. There was no change in LV peak-negative dP/dt or tau. Patients with dilated cardiomyopathy, in contrast, demonstrated no increase in either LV peak-positive dP/dt or the end-systolic pressure-volume ratio, and absence of a progressive leftward shift of their pressure-volume diagrams. Moreover, cardiomyopathy patients demonstrated no increase in LV peak-negative dP/dt or LV peak filling rate and a blunted downward shift of the diastolic limb of their pressure-volume diagrams. Tau, as determined from a derivative method, became abbreviated although never reaching control values. We conclude that patients with dilated cardiomyopathy may demonstrate little or no significant enhancement in systolic and diastolic function during atrial pacing tachycardia, suggesting a depression of both inotropic and lusitropic reserve.

Doppler ultrasound imaging detects changes in tumor perfusion during antivascular therapy associated with vascular anatomic alterations.

Noninvasive monitoring of antiangiogenic therapy was performed by serial power Doppler ultrasound imaging of murine tumors treated with recombinant interleukin 12, the results of which were correlated with assessments of tumor vascularity by microscopy. Growth of established K1735 tumors, but not of IFN-gamma-unresponsive K1735.N23 variants, was suppressed by treatment. Serial Doppler imaging of K1735 tumor vascularity during treatment revealed a progressive change from a diffuse perfusion pattern to a more punctate distribution. Quantitative analysis of the images revealed that color-weighted fractional average, representing overall tumor perfusion, consistently decreased in these tumors, primarily because of a decrease in fractional tumor cross-sectional area carrying blood flow. In contrast, these parameters increased in nonresponsive tumors during treatment. Confocal microscopy of thick tumor sections revealed a reduction in the density and arborization of vessels labeled in vivo by fluorochrome-conjugated lectin with effective treatment. Immunohistological examination of thin tumor sections confirmed the preferential loss of small vessels with successful therapy. Similar changes in tumor vascular anatomy and perfusion were also observed during recombinant interleukin 12 treatment of two other responsive murine tumor types. These results indicate that power Doppler ultrasound is a sensitive, noninvasive method for reporting functional consequences of therapy-induced vascular anatomical changes that can be used to serially monitor tumor perfusion and efficacy of antivascular therapy in clinical trials.

Heart failure with a normal ejection fraction: is measurement of diastolic function necessary to make the diagnosis of diastolic heart failure?

BACKGROUND: The diagnosis of diastolic heart failure is generally made in patients who have the signs and symptoms of heart failure and a normal left ventricular (LV) ejection fraction. Whether the diagnosis also requires an objective measurement of parameters that reflect the diastolic properties of the ventricle has not been established. METHODS AND RESULTS: We hypothesized that the vast majority of patients with heart failure and a normal ejection fraction exhibit abnormal LV diastolic function. We tested this hypothesis by prospectively identifying 63 patients with a history of heart failure and an echocardiogram suggesting LV hypertrophy and a normal ejection fraction; we then assessed LV diastolic function during cardiac catheterization. All 63 patients had standard hemodynamic measurements; 47 underwent detailed micromanometer and echocardiographic-Doppler studies. The LV end-diastolic pressure was >16 mm Hg in 58 of the 63 patients; thus, 92% had elevated end-diastolic pressure (average, 24+/-8 mm Hg). The time constant of LV relaxation (average, 51+/-15 ms) was abnormal in 79% of the patients. The E/A ratio was abnormal in 48% of the patients. The E-wave deceleration time (average, 349+/-140 ms) was abnormal in 64% of the patients. One or more of the indexes of diastolic function were abnormal in every patient. CONCLUSIONS: Objective measurement of LV diastolic function serves to confirm rather than establish the diagnosis of diastolic heart failure. The diagnosis of diastolic heart failure can be made without the measurement of parameters that reflect LV diastolic function.

Direct myocardial effects of OPC-18790 in human heart failure: beneficial effects on contractile and diastolic function demonstrated by intracoronary infusion with pressure-volume analysis.

OBJECTIVES: We sought to determine the precise myocardial effects of OPC-18790 as demonstrated by intracoronary administration. BACKGROUND: Although previous studies have determined the cardiovascular effects of a novel intravenous inotrope, OPC-18790, the observed benefits on contractile and diastolic function may have been confounded by the marked changes in peripheral loading associated with this drug when given intravenously. METHODS: Eight heart failure patients received intracoronary OPC-18790 at 31.25 microg/min for 20 min, and then at 62.5 microg/min for another 20 min. Hemodynamic variables and pressure-volume indexes using the conductance catheter method were determined at baseline and then after the two doses. RESULTS: There were no significant effects on heart rate, cardiac output or loading conditions, including afterload as determined by systemic vascular resistance and arterial elastance (Ea) and preload as determined by end-diastolic volume (EDV). There were significant increases in end-systolic elastance (Ees) from 0.74+/-0.11 to 0.90+/-0.16 mm Hg/ml at 31.25 microg/min and to 137+/-0.33 mm Hg/ml at 62.5 microg/min (p < 0.05 by analysis of variance [ANOVA]). Diastolic function improved, as determined by the time constant for isovolumetric relaxation tau, which decreased significantly from baseline to 31.25 microg/min (94+/-9 to 79+/-9 ms, p < 0.05), and did not shorten further at 62.5 microg/min (78+/-8 ms, p=NS). There were significant decreases in right atrial pressure (9+/-1 to 7+/-1 mm Hg, p < 0.01 by ANOVA) and mean pulmonary artery wedge pressure (21+/-3 to 16+/-2 mm Hg, p < 0.05 by ANOVA). This fall in filling pressures was not accompanied by any change in EDV. Inspection of the diastolic portion of the pressure-volume curve confirmed a downward shift consistent with pericardial release in five of the eight patients. CONCLUSIONS: Intracoronary administration of OPC-18790 demonstrates that the direct myocardial effects of this agent include a modest increase in inotropy and improvement in diastolic function, both of which occur without increases in heart rate, indicating that this agent may be beneficial for the intravenous treatment of congestive heart failure.

Bolus intravenous nitroglycerin predominantly reduces afterload in patients with excessive arterial elastance.

OBJECTIVES: We hypothesized that bolus intravenous nitroglycerin would be an afterload-reducing agent in patients with excessive initial afterload for their level of left ventricular systolic function. Conversely, bolus intravenous nitroglycerin should be a preload-reducing agent in patients without excessive initial afterload. BACKGROUND: Although nitroglycerin has both preload- and afterload-reducing actions, methods to predict its predominant site of action in an individual patient have not been previously described. METHODS: Left ventricular pressure-volume relations were recorded with micromanometer and conductance catheters during bolus injection of intravenous nitroglycerin in 27 patients with both normal left ventricular systolic function and varying degrees of congestive heart failure. Preload was determined by end-diastolic volume, afterload by effective arterial elastance, left ventricular systolic function by end-systolic elastance and coupling of afterload and ventricular function by the ratio of effective arterial elastance to end-systolic elastance (Ea/Ees ratio). An Ea/Ees ratio > 1 was defined as excessive afterload for the level of ventricular function. RESULTS: Patients with an initial Ea/Ees ratio < 1 (Group 1) constituted a group of normotensive patients with intact ventricular function who exhibited a predominant reduction in preload in response to intravenous nitroglycerin. Those with an initial Ea/Ees ratio > 1 and normal or mildly depressed ventricular function (Group 2a) constituted a group of patients, most of whom were hypertensive, who exhibited a predominant afterload reduction. Finally, those with an initial Ea/Ees ratio > 1 and abnormal ventricular function (Group 2b) constituted a group of patients with clinical congestive heart failure who exhibited both preload and afterload reduction but a predominant afterload reduction because stroke volume increased. CONCLUSIONS: Patients with normal arterial elastance and ventricular function respond to nitroglycerin with a predominant preload reduction, whereas patients with either excessive arterial elastance or abnormal ventricular function respond with a predominant afterload reduction.

Influence of contrast media on thrombus formation during coronary angioplasty.

The influence of contrast media on thrombus formation during percutaneous transluminal coronary angioplasty was assessed in 124 consecutive patients undergoing coronary angioplasty and receiving either ionic (n = 57) (Group I) or nonionic (n = 67) (Group II) contrast medium. The presence of thrombus was assessed by qualitative analysis of angiograms in identical pre- and postangioplasty projections by four observers who had no knowledge of other data. Quantitation of stenosis severity before and after angioplasty and qualitative analysis of lesion eccentricity and complexity and of the presence of dissection were also performed. Although the baseline clinical characteristics of the two groups (including presenting syndromes and procedural and angiographic variables) did not differ, more patients in Group II than Group I developed new thrombus during coronary angioplasty (18% vs. 4%, p less than 0.02). In particular, patients with a presenting syndrome of recent myocardial infarction or rest angina, or both, and patients with an eccentric coronary plaque were more likely to develop new thrombus if they received nonionic than if they received ionic contrast medium (p less than 0.05). Patients with new thrombus formation and patients with thrombus present both before and after angioplasty had a high incidence of acute procedural complications (36% and 23%, respectively). Patients in Groups I and II had a similar incidence of ischemic events during follow-up.

Thrombotic thrombocytopenic purpura associated with ticlopidine in the setting of coronary artery stents and stroke prevention.

BACKGROUND: One of the most unusual causes of thrombotic thrombocytopenic purpura (TTP), a life-threatening disease, is ticlopidine hydrochloride, an antiplatelet agent used to prevent strokes in high-risk populations or following coronary artery stent placement. Recently, Hoffman-LaRoche Pharmaceuticals, following reports of 20 deaths from ticlopidine-associated TTP, updated the information about the hematologic adverse effects of the drug. OBJECTIVES: To review our recent findings on ticlopidine-associated hematologic toxic effects, which served as the impetus for the revised warnings, and to discuss the implications of these findings. METHODS: Data were obtained from the Food and Drug Administration's MedWatch program, published phase 3 clinical trials and case reports, hematologists, and plasmapheresis centers. RESULTS: No cases of TTP have been reported in phase 3 ticlopidine trials. In contrast, postmarketing surveillance has identified serious adverse drug reactions to ticlopidine, resulting in 259 deaths, with TTP accounting for 40 of these deaths. Detailed information was available on 98 cases of ticlopidine-associated TTP. Compared with 42 patients in the coronary artery stent setting, 56 patients with ticlopidine-associated TTP in the stroke prevention setting were more likely to be women (62.5% vs 28.6%; P = .01). Before the onset of TTP in patients receiving stroke prevention therapy and patients with stent placement, ticlopidine had been used for less than 2 weeks in 5.4% and 2.4%, between 2 and 3 weeks in 17.9% and 21.4%, between 3 and 4 weeks in 30.4% and 38.1%, and between 4 and 12 weeks in 46.4% and 38.1%, respectively. Death occurred in almost 60% of all patients not receiving plasmapheresis compared with 21.9% of patients receiving plasmapheresis for stroke prevention and 14.3% of patients receiving plasmapheresis in the stent setting. CONCLUSIONS: Use of ticlopidine requires frequent physician visits and laboratory tests for at least 3 months in the stroke prevention setting, while, with short-term use in the coronary artery stent setting, adverse events are less likely to occur. These factors, as well as competition from clopidogrel bisulfate, a new antiplatelet agent, potentially limit the feasibility of ticlopidine as a stroke prevention agent, while having less impact on its use following coronary artery stent placement.

Hemodynamic responses to noninvasive external cardiac pacing.

Although improvements in noninvasive external cardiac pacing have led to a technique with reliable electrical capture and reduced patient discomfort, hemodynamic responses to this pacing mode have not been described previously. Accordingly, this technique was applied to 16 patients with a clinical diagnosis of angina pectoris undergoing cardiac catheterization. Three patients had normal coronary arteries, whereas the remaining 13 had significant coronary artery disease. All patients had noninvasive pacing at increasing heart rates to 85 percent of age-predicted maximal heart rate. At maximal pacing, all patients demonstrated a rise in atrial, pulmonary artery, and mean aortic pressures. Cardiac index remained unchanged, reflecting parallel increases in arteriovenous oxygen difference and oxygen consumption. One minute after cessation of pacing, pulmonary artery pressure and oxygen consumption remained elevated, whereas arteriovenous oxygen difference returned to baseline with a subsequent rise in cardiac index. Angina occurred in eight patients with coronary artery disease at peak pacing and was accompanied by a rise in left ventricular end-diastolic pressure after pacing. In eight patients without pacing-induced angina, including the three patients with normal coronary arteries, there was no significant change in left ventricular end-diastolic pressure after pacing. It is concluded that noninvasive external cardiac pacing produces a rise in both right and left heart filling pressures and in oxygen consumption that persist after pacing, and may provoke angina and hemodynamic abnormalities consistent with myocardial ischemia. This mode of pacing appears hemodynamically safe with maintenance of cardiac index and aortic pressure at 85 percent of maximal age-predicted heart rate.

Hemodynamic and metabolic correlates of dipyridamole-induced myocardial thallium-201 perfusion abnormalities in multivessel coronary artery disease.

The mechanisms responsible for the development of reversible thallium-201 (TI-201) defects with dipyridamole stress in patients with coronary artery disease (CAD) is not well understood. Previous experimental animal studies have demonstrated coronary steal characterized by an absolute decrease in subendocardial flow distal to a stenosis in response to dipyridamole infusion. Accordingly, the purpose of this study was to determine if reversible TI-201 defects in response to dipyridamole infusion are reflective of myocardial ischemia or secondary to regional differences in flow reserve. Dipyridamole (0.56 mg/kg) TI-201 imaging was performed in 23 patients in whom serial electrocardiographic, hemodynamic, aortic and coronary sinus lactate, and coronary sinus adenosine measurements were obtained. All patients with CAD had TI-201 redistribution (3.8 +/- 2.0 defects/patient), and all patients without CAD had normal scans. Mean aortic pressure was similar in both groups and did not change in response to dipyridamole (non-CAD 103 +/- 11 vs CAD 99 +/- 15 mm Hg, p = NS). Pulmonary capillary wedge pressure was similar at baseline (non-CAD 11 +/- 4 vs CAD 13 +/- 5 mm Hg, p = NS) and did not change in response to the drug (non-CAD 14 +/- 3 vs CAD 15 +/- 7 mm Hg, p = NS). Lactate extraction fraction was similar at baseline (non-CAD 0.22 +/- 0.09 vs CAD 0.17 +/- 0.14, p = NS) and decreased similarly in both groups (non-CAD 0.08 +/- 0.06 vs CAD 0.05 +/- 0.12, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Estrogen acutely abolishes abnormal cold-induced coronary constriction in men.

BACKGROUND AND STUDY OBJECTIVE: Ambient cold exposure may induce myocardial ischemia by precipitating coronary artery constriction and a decrease in coronary blood flow. Estrogen has vasoactive properties that may prevent abnormal coronary constriction in a sex-independent manner. The purpose of this study is to determine whether estrogen acutely abolishes abnormal coronary responses to cold exposure in men. DESIGN: Randomized, double-blinded placebo-controlled clinical trial. SETTING: Cardiac catheterization laboratory. PATIENTS: Men referred for routine diagnostic coronary angiography who exhibit abnormal coronary artery constriction in response to a 90-s cold pressor test (CPT). INTERVENTION: Intravenous conjugated estrogens (1.25 mg) vs. placebo. MEASUREMENTS AND RESULTS: Rate-pressure product, coronary cross-sectional area (CSA), and coronary blood flow responses to the CPT were measured before and 15 min after intervention. In 12 men with CPT-induced coronary constriction who were assigned to estrogen, CPT induced a mean 21.8% decrease in coronary CSA (p < 0.01) and a nonsignificant change in coronary flow. After estrogen, the repeated CPT induced a 16.3% increase in CSA (p < 0.01) and a 54.9% increase in flow (p < 0.01). CSA and coronary flow responses to CPT were significantly different before and after estrogen (p < 0.01). In contrast, placebo was not associated with changes in CSA or coronary flow responses to CPT in eight men. CONCLUSIONS: In men, conjugated estrogens acutely abolish abnormal coronary constriction and improve coronary blood flow responses to an exogenous cold stimulus. These results suggest that estrogen favorably alters coronary vasoreactivity in men.

Relationship between left ventricular wall thickness and left atrial size: comparison with other measures of diastolic function.

We postulated that in patients with essential hypertension and normal left ventricular (LV) systolic function, left atrial (LA) size correlates with LV wall thickness by better reflecting the chronicity and duration of LA hypertension than the commonly used hemodynamic and Doppler measures of LV diastolic function. Accordingly, hemodynamic, Doppler, and two-dimensional echocardiographic measurements were performed in 30 subjects with no cardiovascular abnormalities other than essential hypertension (mean systolic blood pressure of 150 +/- 29 mm Hg). The mean LV wall thickness was 0.57 +/- 0.14 cm/m2 and the mean LV ejection fraction was 0.62 +/- 0.12. Hemodynamic and Doppler measures including pulmonary capillary wedge and LV end-diastolic pressures, isovolumic LV pressure relaxation, LV chamber elastic stiffness, and E/A ratio (E and A waves on the pulsed Doppler signal of the mitral valve) correlated poorly (r = 0.01 to -0.52) with LV wall thickness. Both E/A ratio and isovolumic LV pressure relaxation correlated better (p = 0.05) with patient age than with LV wall thickness. In contrast, LA area (in the apical four-chamber view) had a good correlation (r = 0.77 for LA area in atrial diastole and r = 0.86 for LA area in atrial systole) with LV wall thickness. Multiple regression analysis revealed LA area in atrial systole to be the best correlate of LV wall thickness. We conclude that because the left atrium is a thin-walled structure, its size may increase with an increase in LA pressure. In the absence of mitral valve disease and atrial fibrillation, LA size may reflect the chronicity and duration and thus the history of LA hypertension. LA size in the apical four-chamber view may, therefore, provide a simple noninvasive assessment of the degree of LV diastolic dysfunction.

Potential interaction between ritonavir and carbamazepine.

Ritonavir (RTV), a protease inhibitor, and carbamazepine (CBZ), an anticonvulsant, were administered concurrently to a patient who had human immunodeficiency virus infection and epilepsy. The combination resulted in elevated serum concentrations of CBZ, with accompanying vomiting, vertigo, and transient liver dysfunction. After discontinuing RTV and reducing the dosage of CBZ, the serum concentration of CBZ returned to the optimal range, symptoms subsided, and liver function returned to baseline. Carbamazepine is metabolized in the liver to a large extent by the cytochrome P450 (CYP) system, especially CYP3A4, 2C8, and 1A2, whereas RTV is metabolized primarily by CYP3A and is a potent inhibitor of this enzyme. Careful clinical monitoring may help prevent adverse drug interactions when these drugs are administered concurrently.

Factitious disorder by proxy: awareness among mental health practitioners.

Factitious disorder by proxy (FDP) is a form of abuse in which a caregiver surreptitiously simulates or induces illnesses in a person for whom he or she cares. Typically, a mother is the perpetrator and at least one of her children is victimized. FDP has a high morbidity and mortality rate, and a knowledgeable health team increases the primary physician's confidence in making this difficult diagnosis. The purpose of this study was to determine the levels of awareness of FDP among mental health practitioners and their sources of information. Anonymous questionnaires were sent to 687 primary care physicians and mental health practitioners. Psychiatrists (89%) and psychologists (69%) were more aware of the disorder than were social workers (42%). Years in practice were not associated with awareness of FDP. Psychiatrists were more likely than psychologists or social workers to have had exposure through an actual case or through their professional journals. These findings were statistically significant. Awareness of FDP varies significantly among mental health professionals and may reflect the availability of information during training and in journals. Since social workers and psychologists often have earlier and broader opportunities than psychiatrists to interface with families, enhancements in training and the professional literature in these disciplines are needed if FDP is to be consistently considered and identified.

Factitious deafblindness: an imperceptible variant of factitious disorder.

We describe two women who, over a period of years, feigned the loss of both vision and hearing. Their principal motive appeared to be pursuit of the sick role, though each acquired disability payments as well. A face-saving intervention sharply reduced the alleged hearing deficits in one case; the other patient precipitously left treatment. A broad range of permutations of factitious disorder has been reported, but these appear to be the first published cases of factitious deafblindness.

Concurrent factitious disorder and factitious disorder by proxy. Double jeopardy.

Two forms of medical dissimulation-factitious disorder and factitious disorder by proxy-present enormous challenges to clinicians accustomed to receiving valid symptom reports from their patients. The consequences of such "disease forgery" are heightened when a patient simultaneously engages in both forms of deception. We discuss a 34-year-old nurse who simulated or induced a panoply of physical and psychological ailments in both herself and her daughter. The staff's insistence on access to outside information sources proved indispensible in establishing both diagnoses, facilitating ongoing treatment for the patient and ensuring appropriate protection of the child.

Use of the metaphyseal-diaphyseal angle in the evaluation of bowed legs.

We evaluated the accuracy of the angle described by Levine and Drennan, the metaphyseal-diaphyseal angle of the proximal aspect of the tibia, for the differentiation of physiological bowing from Blount disease. We compared this angle, as measured at presentation, in 106 children (179 extremities) who had physiological bowing with the angle in nineteen children (thirty-two extremities) who had documented Blount disease. The angle averaged 9 +/- 3.9 degrees for the patients who had physiological bowing and 19 +/- 5.7 degrees for the patients who had Blount disease (p < 0.0000001). Linear regression analysis, performed to evaluate any changes in the metaphyseal-diaphyseal angle in relation to age, showed that the older the child was at the time of presentation the more likely it was that the angle would be smaller in a child who had physiological bowing and larger in a child who had Blount disease. The chance for false-positive and false-negative errors was greater than 5 per cent if the angle was more than 9 degrees but less than 16 degrees. Sixty-six (37 percent) of the 179 extremities in the group that had physiological bowing had an angle of at least 11 degrees; one extremity affected by Blount disease had an angle of less than 11 degrees. In this study, we found that the metaphyseal-diaphyseal angle may be helpful in the identification of Blount disease but should not be the sole criterion used to determine the diagnosis.

Micromechanical devices for intravascular drug delivery.

Microfabrication technology, more commonly applied to the manufacture of integrated circuits, can be used to build devices useful for mechanical delivery of drugs and genes. Microprobes fabricated using silicon micromachining have been used to deliver DNA into cells as an alternative to bombardment and microinjection. This idea can be extended to intravascular stents with integrated microprobes capable of piercing compressed plaque and delivering anti-restenosis therapies into coronary arteries. Preliminary experiments using filleted rabbit arteries have demonstrated transection of the internal elastic lamina. New nonplanar microfabrication technologies are necessary for creating practical devices with cylindrical symmetry; a promising possibility is to use microfabricated structures of anodic metal oxides.

A comparison of monopolar electrosurgery to a new multipolar electrosurgical system in a rat model.

OBJECTIVES/HYPOTHESIS: The purpose of this study is to compare collateral tissue damage and wound healing in incisions created by electro-dissociation and conventional electrosurgery. Conventional electrosurgery has been used as an alternative to the scalpel to improve hemostasis. However, the heat generated by this instrument can cause tissue damage surrounding the incision, limiting its use around nerves and large blood vessels. A new technology, Coblation (Arthrocare Corp., Sunnyvale, CA), uses "electro-dissociation" to achieve similar results by creating charged particles from a conductive medium to make an incision while simultaneously achieving hemostasis. This new approach to electrosurgery may reduce soft tissue damage. METHODS: Two prospective, matched design experiments were performed. In experiment I, both devices were set at the same electrical power in watts and then used to create an incision on the tongue of rats. In experiment II, the electrical power settings of both devices were adjusted until they created incisions of the same size. Epithelial destruction and collateral tissue damage were measured in histologically prepared tissue in both experiments, and the wound healing process was observed in experiment II at 0, 3, 7, and 14 days after surgery. RESULTS: The results showed that the electro-dissociation method created significantly less epithelial destruction and collateral tissue damage in both experiments. Granulation tissue formation was also significantly less extensive in the electrodissociation-induced incision after 7 and 14 days of recovery. CONCLUSIONS: Wound healing may be faster than with conventional electrosurgery if the Coblation device is used.