New approach to measuring oxygen diffusion and consumption in encapsulated living cells, based on electron spin resonance microscopy.

Cell microencapsulation within biocompatible polymers is an established technology for immobilizing living cells that secrete therapeutic products.  These can be transplanted into a desired site in the body for the controlled and continuous delivery of the therapeutic molecules.  One of the most important properties of the material that makes up the microcapsule is its oxygen penetrability, which is critical for the cells' survival.  Oxygen reaches the cells inside the microcapsules via a diffusion process.  The diffusion coefficient for the microcapsules' gel material is commonly measured using bulk techniques, where the gel in a chamber is first flushed with nitrogen and the subsequent rate of oxygen diffusion back into it is measured by an oxygen electrode placed in the chamber.  This technique does not address possible heterogeneities between microcapsules, and also cannot reveal O2 heterogeneity inside the microcapsule resulting from the living cells' activity.  Here we develop and demonstrate a proof of principle for a new approach to measuring and imaging the partial pressure of oxygen (pO2) inside a single microcapsule by means of high-resolution and high-sensitivity electron spin resonance (ESR).  The proposed methodology makes use of biocompatible paramagnetic microparticulates intercalated inside the microcapsule during its preparation.  The new ESR approach was used to measure the O2 diffusion properties of two types of gel materials (alginate and extracellular matrix - ECM), as well as to map a 3D image of the oxygen inside single microcapsules with living cells. STATEMENT OF SIGNIFICANCE: The technology of cell microencapsulation offers major advantages in the sustained delivery of therapeutic agents used for the treatment of various diseases ranging from diabetes to cancer. Despite the great advances made in this field, it still faces substantial challenges, preventing it from reaching the clinical practice. One of the primary challenges in developing cell microencapsulation systems is providing the cells with adequate supply of oxygen in the long term. Nevertheless, there is still no methodology good enough for measuring O2 distribution inside the microcapsule with sufficient accuracy and spatial resolution without affecting the microcapsule and/or the cells' activity in it. In the present work, we introduce a novel magnetic resonance technique to address O2 availability within cell-entrapping microcapsules. For the first time O2 distribution can be accurately measured and imaged within a single microcapsule. This new technique may be an efficient tool in the development of more optimal microencapsulation systems in the future, thus bringing this promising field closer to clinical application.

Innovative encapsulation platform based on pancreatic extracellular matrix achieve substantial insulin delivery.

Cell-based therapies for the treatment of diabetes, generally aim to provide long-term glucose regulated-insulin delivery using insulin producing cells. The delivery platform is crucial for the therapeutic outcome as well as for immunoisolation of the entrapped cells. We have developed a novel artificial pancreas encapsulation platform for the treatment of diabetes that is based on solubilized whole porcine pancreatic extracellular matrix (ECM). These unique capsules were used to entrap human liver cells and mesenchymal stem cells that were induced to differentiate into glucose-regulated insulin-producing cells. We demonstrate that the ECM-microcapsule platform provides a natural fibrous 3D niche, supporting cell viability and differentiation, while significantly improving insulin delivery. In vivo, ECM-encapsulated cells were shown to be non-immunogenic, and most importantly, to significantly improve the glycemic control in diabetic mouse preclinical model, thus establishing a proof-of-concept for this new cell-based insulin delivery platform.

Augmented short- and long-term hemodynamic and hormonal effects of an angiotensin receptor blocker added to angiotensin converting enzyme inhibitor therapy in patients with heart failure. Vasodilator Heart Failure Trial (V-HeFT) Study Group.

BACKGROUND: ACE inhibitors may not adequately suppress deleterious levels of angiotensin II in patients with heart failure. An angiotensin receptor blocker added to an ACE inhibitor may exert additional beneficial effects. METHODS AND RESULTS: Eighty-three symptomatic stable patients with chronic heart failure receiving long-term ACE inhibitor therapy were randomly assigned to double-blind treatment with valsartan 80 mg BID, valsartan 160 mg BID, or placebo while receiving their usual ACE inhibitor therapy. Studies were performed before and after the first dose of the test drug and again after 4 weeks of therapy. A single dose of lisinopril was administered during study days to ensure sustained ACE inhibition. Compared with placebo, the first dose of valsartan 160 mg resulted in a significantly greater reduction in pulmonary capillary wedge pressure at 3, 4, and 8 hours and during the prespecified 4- to 8-hour interval after the dose and in systolic blood pressure at 2, 3, 6, 8, and 12 hours and 4 to 8 hours after the dose. A pressure reduction from valsartan 80 mg did not achieve statistical significance. After 4 weeks of therapy, net reductions in 0-hour trough pulmonary capillary wedge pressure (-4.3 mm Hg; P=0. 16), pulmonary artery diastolic pressure (-4.7 mm Hg; P=0.013), and systolic blood pressure (-6.8 mm Hg; P=0.013) were observed in the valsartan 160 mg group compared with placebo. After 4 weeks of therapy, plasma aldosterone was reduced by valsartan 80 mg BID (-52. 1 pg/mL; P=0.001) and 160 mg BID (-47.8 pg/mL; P<0.001) compared with placebo, and there was a trend for a reduction in plasma norepinephrine (-97 pg/mL; P=0.10). Seventy-four of the 83 patients completed the trial. CONCLUSIONS: Physiologically active levels of angiotensin II persist during standard long-term ACE inhibitor therapy.

Prognostic importance of the serum magnesium concentration in patients with congestive heart failure.

Magnesium abnormalities are common in patients with congestive heart failure but the clinical and prognostic significance of an abnormal serum magnesium concentration in this disorder has not been investigated. Therefore, the relation between serum magnesium concentration and the clinical characteristics and long-term outcome of 199 patients with chronic heart failure was evaluated. The serum magnesium concentration was less than 1.6 mEq/liter in 38 patients (19%), within the normal range in 134 patients (67%) and greater than 2.1 mEq/liter in 27 patients (14%). Patients with hypomagnesemia had more frequent ventricular premature complexes and episodes of ventricular tachycardia than did patients with a normal serum magnesium concentration (p less than 0.05). Even though the two groups were similar with respect to severity of heart failure and neurohormonal variables, patients with a low serum magnesium concentration had a significantly worse prognosis during long-term follow-up (45% versus 71% 1 year survival, p less than 0.05). Patients with hypermagnesemia had more severe symptoms, greater neurohormonal activation and worse renal function than did patients with a normal serum magnesium concentration but tended to have fewer ventricular arrhythmias. Hypermagnesemic patients had a worse prognosis than did those with a normal magnesium concentration (37% versus 71% 1 year survival, p less than 0.05). In conclusion, the measurement of serum magnesium concentration provides important clinical and prognostic information in patients with chronic heart failure.

Thromboembolism following cardioversion of "common" atrial flutter. Risk factors and limitations of transesophageal echocardiography.

Based on multiple recent studies, anticoagulant therapy is recommended prior to elective cardioversion for patients with atrial fibrillation of more than 24 h duration. The value of anticoagulation in patients with atrial flutter, however, is less well established. Published recommendations for pericardioversion anticoagulation of atrial fibrillation often do not extend to patients with atrial flutter. We evaluated the risk of thromboembolism in our patient population undergoing cardioversion for atrial flutter. Over a period of 30 months, clinically indicated electrical cardioversions were performed in 41 patients with "common" atrial flutter. Sixteen of these patients underwent transesophageal echocardiograms immediately prior to cardioversion to exclude a left atrial thrombus. Three of the 41 patients with atrial flutter developed neurologic ischemic syndromes within 48 h of elective cardioversion. All three patients who developed ischemic neurologic complications had undergone transesophageal echocardiography immediately prior to cardioversion and did not have any evidence of left atrial clot. One patient had cardiomyopathy and the other two had left ventricular hypertrophy. Thus, electrical cardioversion without anticoagulation in patients with atrial flutter and associated heart disease is associated with a risk of thromboembolic events. A normal transesophageal echocardiogram is of doubtful value in prevention of thromboembolic complications.

Pilot study of a unique film dressing for the treatment of donor site wounds.

The clinical benefits of using the VENTEX Wound Dressing System (VWDS) (The Kendall Co.) in the management of donor site wounds were evaluated in this pilot study involving 10 informed and consenting patients. The study was a prospective, randomized, controlled study in which one donor site wound was managed with VWDS, and the other donor site wound on the same patient was managed by our standard of care, which involved the use of Xeroform gauze (The Kendall Co.). Each donor site wound was independently assessed daily for pain, rate of reepithelialization, adverse reactions, and ease of dressing use while patients were hospitalized. Quality of scar was assessed during regularly scheduled follow-up visits. The use of VWDS eliminated donor site pain and accelerated reepithelialization compared with Xeroform gauze. There were no adverse reactions associated with the use of VWDS. In contrast, there were two cases of suspected infection at the donor sites treated with Xeroform gauze. The VWDS was more complicated to apply and use compared with Xeroform gauze. There were no differences observed in scar quality of donor sites treated with these dressings.

Adaptive housing: remodeling considerations for the disabled.

The disabled are handicapped only to the extent that they are prevented from being normal. The process of normalization is hampered by physical barriers in the home that make life difficult for disabled persons. Staff can be trained to eliminate these architectural barriers in the home, focusing primarily on accessibility, the bathroom, the bedroom, and the kitchen. Completion of the barrier-free design of the home should provide a cost-effective means for improving the quality of life for disabled persons and their families.

Computer analysis of the performance of the BTE Work Simulator.

The BTE Work Simulator (Baltimore, Therapeutic Equipment Co., Hanover, Md.) recreates the work environment by providing a rotatable shaft to which a variety of tools can be attached. The patient can simulate the coordinated muscle and joint movements involved in the work situation, exercising either isometrically or isotonically, and thereby increase the potential for return to work. The BTE Work Simulator has four major components: the exercise head to provide variable resistance, tools that attach to the exercise head, a control console containing a microprocessor that calculates work and power, and the Quest software package (Baltimore Therapeutic Equipment Co.). Quest provides four static/isometric and seven dynamic/isotonic tests that can be used to document the extent of a patient's impairment. In addition, it has daily treatment options and acts as an extensive data base capable of retrieving any stored test or treatment results. This software system greatly facilitates the use of the BTE Work Simulator by providing instant calculations of power and coefficients of variation, immediate patient feedback, graphic expansion of the data, and printed evaluation reports.

Aquatic access for the disabled.

Innovations in rehabilitation engineering can now provide aquatic access for the disabled. In the regional burn center, the Bodi-Gard cart shower system (Hospital Therapy Products, Inc., Wood Dale, Ill.) uses three flexible hoses to provide precise hydrotherapy and debridement. Its main mixing valve controls temperature and pressure and is easily disinfected by an in-line chamber. This shower system is complemented by the foldable Bodi-Gard mobile seat shower system (Hospital Therapy Products, Inc.). This system, which is covered by a disposable liner, surrounds the patient with eight water jets that empty into any floor drain. The Bather 2001 (Silcraft Corp., Traverse City, Mich.) is a fiberglass hydrotherapy bathtub with a unique Aqua-Seal door (Silcraft Corp.) that can be raised to provide patient access. Its unique closed-loop disinfection system prevents contamination of its internal components. The Nolan Tublift (Aquatic Access, Louisville, Ky.) is a lightweight, removable lift that uses water power to gently raise and lower its seat. It can be manually swiveled to allow access from a wheelchair. Transfer benches span the tub wall to provide access to the shower and bathtub. Although they are a less expensive alternative to the Tublift, they allow water to spill outside the tub, which may create a slippery bathroom floor. The Nolan Poolift (Guardian Products, Arleta, Calif.) is a water-powered pool lift, which automatically rotates as it descends. It is capable of lifting up to 135 kg with a home water pressure of 55 psi. In contrast, the water-powered Aquatic Access Poolift is a less expensive pool lift, which rotates manually with assistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Therapeutic ultrasound-mediated DNA to cell and nucleus: bioeffects revealed by confocal and atomic force microscopy.

Therapeutic ultrasound (TUS) has the potential of becoming a powerful nonviral method for the delivery of genes into cells and tissues. Understanding the mechanism by which TUS delivers genes, its bioeffects on cells and the kinetic of gene entrances to the nucleus can improve transfection efficiency and allow better control of this modality when bringing it to clinical settings. In the present study, direct evidence for the role and possible mechanism of TUS (with or without Optison) in the in vitro gene-delivery process are presented. Appling a 1 MHz TUS, at 2 W/cm(2), 30%DC for 30 min was found to achieve the highest transfection level and efficiency while maintaining high cell viability (>80%). Adding Optison further increase transfection level and efficiency by 1.5 to three-fold. Confocal microscopy studies indicate that long-term TUS application localizes the DNA in cell and nucleus regardless of Optison addition. Thus, TUS significantly affects transfection efficiency and protein kinetic expression. Using innovative direct microscopy approaches: atomic force microscopy, we demonstrate that TUS exerts bioeffects, which differ from the ones obtained when Optison is used together with TUS. Our data suggest that TUS alone affect the cell membrane in a different mechanism than when Optison is used.

The role of angiotensin receptor blockers in heart failure.

The effectiveness of ACE inhibitors in reducing morbidity and mortality in patients with heart failure is largely attributable to their suppression of angiotensin II production. Despite chronic therapy with ACE inhibitors, angiotensin II levels may be incompletely suppressed and contribute to the high mortality of patients with heart failure. Recently, angiotensin receptor blockers, which block the effects rather than the production of angiotensin II, have become available. Angiotensin receptor blockers have been evaluated as both monotherapy and in combination with ACE inhibitors. In short term studies, angiotensin receptor blocker monotherapy appears to share many of the hemodynamic and clinical features of ACE inhibitors. In a long-term study, the Losartan Heart Failure Survival Study, angiotensin receptor blockers failed to demonstrate any beneficial effect over that seen with ACE inhibitors. The addition of an angiotensin receptor blocker to an ACE inhibitor appears to exert favorable short term hemodynamic, clinical, and neurohormonal effects. Four ongoing trials, Valsartan Heart Failure Trial, Candesartan in Heart Failure Assessment of Reduction in Mortality and Morbidity, Optimal Therapy in Myocardial Infarction with Angiotensin II Antagonist Losartan study, and Valsartan In Acute Myocardial Infarction study, are evaluating the role of angiotensin receptor blockers either alone or in combination with ACE inhibitors in the management of left ventricular dysfunction. (c)2000 by CHF, Inc.

Pharmacodynamic effects of milrinone with and without a bolus loading infusion.

BACKGROUND: Milrinone is a positive inotropic agent with vasodilatory and lusitropic activity. Milrinone dosed as a 50 microg/kg bolus followed by a continuous infusion provides an immediate and sustained hemodynamic response. The comparative pharmacodynamics of a placebo bolus and a milrinone bolus followed by a continuous milrinone infusion in patients with decompensated heart failure are unknown. METHODS: Nineteen patients with decompensated heart failure underwent right heart catheterization and were randomized to receive an intravenous infusion of milrinone at a rate of 0.50 microg/kg/min with (n = 9) or without (n = 10) a preceding 50 microg/kg bolus. Pulmonary capillary wedge pressure, cardiac index, and plasma milrinone levels were measured serially over 24 hours. RESULTS: In the milrinone bolus group, maximal effects on plasma concentration (352.3 ng/mL), cardiac index (+0.97 L/min/m(2), P =.02), and pulmonary capillary wedge pressure (-11.25 mm Hg, P <.001) were seen after the loading dose. In the placebo loading dose group, significant hemodynamic effects were observed starting at 30 minutes after the start of the continuous infusion. Changes in pulmonary capillary wedge pressure (placebo -8.6 vs milrinone -8.78 mm Hg, P not significant [NS]) were similar in both groups at 2 hours, whereas changes in cardiac index (placebo loading +0.81 vs milrinone loading +0.78 L/min/m(2), P NS) and milrinone levels (placebo loading 168.0 vs milrinone loading 165.6 ng/mL, P NS) were similar at 3 hours. One patient randomized to a milrinone bolus demonstrated a marked decrease in blood pressure and was discontinued from therapy. CONCLUSIONS: A milrinone infusion without a bolus appears to be a rapidly effective inotropic strategy that may have an improved safety profile during the initiation of therapy compared with a continuous infusion strategy initiated with a bolus.

Preadmission psychosocial screening of older orthopedic surgery patients: evaluation of a Social Work Service.

A preadmission social work intervention was evaluated for impact on length of hospital stay (LOS) and patient satisfaction. Psychosocial issues related to function and post-discharge needs were assessed at an exploratory level. A modified post-test only control group design was used. Study group patients were screened before hospitalization and offered services on admission. Control group patients received standard care. Study group patients were significantly more satisfied with services but impact on length of stay was not demonstrated with one possible exception. Post-operative complications were significantly related to longer LOS; however, unlike control group patients, study group patients with complications did not have significantly longer LOS. Women and those limited in preadmission physical function were most likely to report insufficient help after discharge. A more intensive preadmission intervention is recommended to improve impact on LOS and informal support system involvement, while future outcome studies would clarify the nature of service gaps and high risk groups.

A study of the efficacy and safety of irbesartan in combination with conventional therapy, including ACE inhibitors, in heart failure. Irbesartan Heart Failure Group.

Because heart failure therapy with angiotensin-converting enzyme (ACE) inhibitors may not be optimal, owing to persistent levels of angiotensin II occurring through incomplete blockade and alternate pathways, the benefit of adding irbesartan, an angiotensin receptor antagonist, to conventional therapy, including ACE inhibitors, was examined. In this multicentre, randomised, double-blind, placebo-controlled study, 109 patients with heart failure (New York Heart Association functional class II and III) and left ventricular ejection fraction (LVEF) < or = 40% received stable doses of ACE inhibitors and diuretics before and throughout the study. Irbesartan was titrated as tolerated to 150 mg once daily in all patients. Exercise tolerance time (ETT), LVEF and clinical status were assessed at baseline and after 12 weeks. Compared with placebo, irbesartan in combination with conventional therapy, including ACE inhibitors, produced favourable trends in ETT and LVEF and was well tolerated in patients with mild to moderate heart failure.

Felodipine improves left ventricular emptying in patients with chronic heart failure: V-HeFT III echocardiographic substudy of multicenter reproducibility and detecting functional change.

BACKGROUND: The echocardiographic substudy of the Vasodilator-Heart Failure Trial III (V-HeFT III) aimed to determine if felodipine treatment in patients with heart failure who were taking an angiotensin-converting enzyme inhibitor had a favorable effect on left ventricular (LV) structure and function. Earlier V-HeFT trials showed that hydralazine-isosorbide dinitrate improved ejection fraction (EF) and survival, whereas enalapril achieved greater survival with smaller increases in EF. Would the combination of a potent vasodilator and enalapril produce greater improvements in function and survival? METHODS AND RESULTS: Doppler-echocardiographic data were collected from 260 males with heart failure who were randomized to felodipine or a placebo. Mean intrasubject differences between baseline, at 3 months, and at 12 months were compared. Intersite and intrareader reproducibilities were measured from duplicate recordings and readings. At 3 months, no changes in ultrasound variables from baseline occurred in either group. At 12 months, felodipine patients achieved greater increases in EF, shortening of LV end-systolic length, and increases in stroke volume index. Reproducibility coefficients of variation were 7.4% (EF), 6.0% (end-diastolic length), and 13.0% (stroke volume index). CONCLUSIONS: The echocardiographic substudy showed that felodipine, added to heart failure therapy, increased EF, shortened end-systolic length, and increased stroke volume index. The changes were small and confirmed that reproducibility from multiple laboratories can be coordinated into a useful research tool.

Effect of the calcium antagonist felodipine as supplementary vasodilator therapy in patients with chronic heart failure treated with enalapril: V-HeFT III. Vasodilator-Heart Failure Trial (V-HeFT) Study Group.

BACKGROUND: Despite therapy with diuretics, ACE inhibitors and digoxin morbidity and mortality in heart failure remain high and might respond favorably to an additional vasodilator. METHODS AND RESULTS: Male patients (n=450) with chronic heart failure (cardiac dysfunction and impaired exercise performance) on optimal current therapy (97% enalapril, 89% diuretics) were randomly assigned to double-blind treatment with felodipine extended release (5 mg BID) or placebo for 3 to 39 months (average, 18 months). Felodipine significantly reduced blood pressure and, at 3 months, increased ejection fraction (2.1% versus -0.1% units in the placebo group, P=.001) and reduced plasma atrial natriuretic peptide levels (-2.9 versus 26.9 pg/mL in the placebo group, P=.01) but did not improve exercise tolerance, quality of life, or the need for hospitalization. During long-term follow-up, the favorable effects on ejection fraction and atrial peptide did not persist, but felodipine prevented worsening exercise tolerance and quality of life. In the felodipine and placebo groups, mortality (13.8% versus 12.8%, respectively) and hospitalization (43% versus 42%) rates were similar, and a higher incidence of peripheral edema was the only apparent side effect of felodipine therapy. CONCLUSIONS: Felodipine exerts a well-tolerated additional sustained vasodilator effect in patients with heart failure treated with enalapril, but the only possible long-term benefit was a trend for better exercise tolerance and less depression of quality of life in the second year of treatment. The drug appears to be safe but not clearly efficacious in patients with heart failure.