Search

Carvedilol is a vasodilating beta-blocker and antioxidant approved for treatment of mild to moderate hypertension. angina, and congestive heart failure. Metoprolol is a beta1-selective adrenoceptor antagonist. When carvedilol and metoprolol were recently compared in clinical trials for heart failure, each showed beneficial beta-blocker effects such as improved symptoms, quality of life, exercise tolerance, and ejection fraction, with no between-group differences. When thiobarbituric acid reactive substance (TBARS) levels were measured in serum as an indirect marker of free radical activity, there were also no between-group differences. However, we had noted superior cardioprotection by carvedilol in comparison to metoprolol in ischemia and reperfusion models. We therefore examined antioxidant activity directly in cells and tissues. Here we show that in cultured rat cerebellar neurons, and in brain and heart membranes, carvedilol has far greater antioxidant activity than metoprolol, which is essentially inactive as an antioxidant in these model systems. The antioxidant activity of carvedilol could be explained by a greater degree of lipophilicity, as measured by its ClogP value of 3.841 as contrasted to a ClogP value of 1.346 for metoprolol. Alternatively, the molecular structure of carvedilol favors redox recycling, which the structure of metoprolol does not. Therefore, carvedilol could have additional pharmacologic effects that are favorable for long-term therapy.

Murine MARCO has been identified recently in subsets of macrophages located in the peritoneum, marginal zone of the spleen, and the medullary cord of lymph nodes, where it has been proposed that it serves as a bacteria-binding receptor. A scavenger receptor family member with an extended collagenous domain, murine MARCO has also been demonstrated in atherosclerotic lesions of susceptible mice. We report here the identification, tissue and chromosomal localization, and pharmacological characterization of human (h)MARCO. hMARCO was identified from a macrophage cDNA library by electronic screening with the murine MARCO sequence. Nucleotide sequence analysis confirmed that the full-length hMARCO clone encoded a 519-amino acid protein sharing 68.5% identity with murine MARCO. RNA blot analysis indicated that the hMARCO transcript is 2.0 kb in length and is predominantly expressed in human lung, liver, and lymph nodes. Radiation hybrid mapping localized hMARCO to chromosome 2q14. Ligand-binding studies of COS cells expressing hMARCO demonstrated significant specific binding of both Escherichia coli and Staphylococcus aureus. In contrast, the hMARCO receptor expressed in COS cells did not specifically bind the scavenger receptor ligand acetylated low-density lipoprotein (LDL), despite its similarity to the elongated collagen-like binding domain of the macrophage scavenger receptor. In addition, acetylated (Ac)LDL and oxidized (Ox)LDL did not inhibit E. coli binding to hMARCO. These data suggest that hMARCO may play an important role in host defense, but it has no obvious role in the accumulation of modified lipoproteins during atherogenesis.

Oxidized low-density lipoprotein (OxLDL) plays a critical role in foam cell formation and atherosclerogenesis. A cDNA encoding adipophilin was identified in cultured human macrophages stimulated with OxLDL using mRNA differential display. Adipophilin is a 50 kDa protein known to be a specific marker for adipocyte cell differentiation and lipid accumulation in a variety of cells. The time-dependent induction of adipophilin mRNA in macrophages was specific to OxLDL but not native LDL, and not to various cytokines and serum. In human atherosclerotic lesions, adipophilin mRNA expression was localized in a subset of lipid-rich macrophages. These data suggest that adipophilin-expressing macrophages may represent foam cells and this gene expression is likely to be associated with the lipid accumulation in foam cells of the atherosclerotic lesions.

Class A scavenger receptor (SR-A) antagonists may prevent the initiation of atherosclerosis, because a recent report found that SR-A/apolipoprotein E (apoE) double-knockout mice had 60% smaller lesions than apoE single-knockout littermates. We transfected human embryonic kidney (HEK) 293 cells with SR-A type I or II receptors to find small-molecule antagonists. Uptake of 1,1'-dioctadecyl-3,3,3', 3'-tetramethylindocarbocyanine perchlorate-labeled acetylated low-density lipoprotein (DiI-AcLDL) showed that among common polyanionic ligands, polyinosine was the most potent, with an IC50 of 0.74 microgram/ml, whereas the novel compound (E)-methyl 4-chloro-alpha-[4-(4-chlorophenyl)-1, 5-dihydro-3-hydroxy-5-oxo-1-(2-thiazolyl)-2H-pyrrol-2-ylidene]benzene acetate gave an IC50 of 6.1 microgram/ml (13 microM). The novel antagonist also inhibited DiI-AcLDL uptake in cultured human peripheral and rat peritoneal macrophages with IC50 values of 21 microM and 17 microM, respectively. With [125I]AcLDL as ligand for transfected HEK 293 cells, binding/uptake and degradation at 37 degrees C for 5 h was saturable and selective. In a comparison of both types of receptor, we found no difference between the capacity of SR-AI or SR-AII for either binding or degradation. Polyinosine competed both [125I]AcLDL binding and degradation with a Ki of 1 microgram/ml, whereas the novel antagonist competed with a Ki of 19 microgram/ml (40 microM) and 8.6 microgram/ml (18 microM), respectively, for binding and degradation. Saturation binding in the presence of the ionophore monensin indicated that the novel compound behaved as a noncompetitive antagonist and perhaps as an allosteric effector. This is the first report to describe a small-molecule macrophage scavenger receptor antagonist. Utilization of this permanently transfected HEK 293 cell line will allow the identification of more potent macrophage scavenger receptor antagonists, so that their utility as therapeutics for atherosclerosis can be determined.

Calcification of glutaraldehyde-preserved bioprosthetic heart valves (BHVs) results in their clinical failure. The mechanism of this pathologic calcification is not well defined. Since serum proteins are known to be taken up in mineralized tissue, we hypothesized that serum proteins derived from several calcium-binding noncollagenous proteins (NCPs) of bone and teeth also may be associated with pathologically mineralized BHVs. Using a rat subdermal model of BHV calcification, glutaraldehyde-preserved bovine pericardium (GPBP) was implanted for 1, 3, 14, and 60 days, and then subjected to an extraction procedure designed to isolate only NCPs tightly bound to the mineral phase. Gel electrophoresis and Coomassie Brilliant Blue staining demonstrated that these proteins became associated with GPBP over time, paralleling reported calcium uptake by the tissue. Stains-All staining demonstrated a marked accumulation of highly acidic, phosphorylated NCPs associated with 60-day GPBP extracts. Some of these proteins were detected in rat serum but were absent from extracts of GPBP incubated in rat serum in vitro. Western blotting with antibodies to three NCPs found in bone and teeth-bone acidic glycoprotein 75 (BAG 75), osteopontin, and SPARC-demonstrated that these NCPs were tightly bound to the mineral phase of calcified GPBP. A fourth NCP, bone sialoprotein II (BSP II) was barely detectable. Thus each identified NCP showed a different pattern of GPBP association relative to mineral deposition, suggesting unique roles for each in pathologic calcification. SPARC increased within 3 days of GPBP implantation but decreased by 2 weeks. BAG 75 and osteopontin uptake was detected in the initial mineral deposits and increased mineralization proceeded. BSP II never increased significantly over the entire-period. Further studies, which should include immunohistochemistry, will be important for delineating the source, location, and function of these three NCPs and for identifying others that also may be involved in this pathological process. Most important, the new insights into the mechanism of pathologic calcification described here present exciting opportunities for novel approaches to BHV calcification prevention.

Objectives: To study the feasibility of transmitting full-length diagnostic-quality echocardiograms with video conferencing systems linked by ISDN., Methods: Forty-three previously video-recorded full-length echocardiograms (22 complete two-dimensional Doppler studies, 21 separate M-mode studies) were transmitted from a site 30 miles distant using desktop video conferencing systems linked with one ISDN line (128 kbps). Blinded interpretations of the original recorded and transmitted studies were made by two pediatric cardiologists (two-dimensional Doppler) and a pediatric sonographer (M-mode)., Results: Diagnoses of normal (N = 12) and abnormal (N = 10) conditions were made from the original tapes; the same interpretations were made from the transmitted studies. Twenty-one specific abnormalities in the 10 abnormal studies were seen on both original and transmitted videotapes. These abnormalities ranged from simple congenital heart defects, including ventricular septal defect, atrial septal defect, and patent ductus arteriosus, to complex ones, such as coronary artery fistula, double-outlet right ventricle, and complete atrioventricular canal. Qualitatively, there was mild degradation in gray scale, brightness, and contrast of the images. Six M-mode variables from the transmitted images had excellent concordance with the original tracings (P = 0.506 to 0.838; r = 0.86 to 0.97)., Conclusions: Although our sample size was small, this preliminary experience indicates that video conferencing equipment utilizing ISDN technology is a reliable method for transmitting full-length diagnostic-quality echocardiographic studies from remote sites. This technology may have a significant impact on the management of pediatric patients with suspected heart disease. Further evaluation is warranted.

Recombinant human immunodeficiency virus (HIV-1) Tat protein added to the culture medium of rat cerebellar neurons promoted aggregation and formation of spoke-like neurites in a dose-dependent manner. Tat proteins containing mutations in the Arg-Gly-Asp (RGD) cell adhesion motif or a deletion of the cysteine-rich domain had no effect on neuronal morphology. In contrast, a Tat protein that contained a deletion of the proline-rich domain promoted neuronal aggregation. Aggregation of neurons was inhibited by the addition of monoclonal antibodies directed against the RGD and basic domains of Tat, but not against the proline-rich domain. The same domains of Tat required to induce aggregation also mediated adhesion of neurons to Tat-coated substrates. The HIV-2 Tat protein, which lacks an RGD sequence but contains cysteine-rich and basic domains similar to HIV-1 Tat, induced aggregation and acted as a substrate for adhesion when added at higher concentrations than HIV-1 Tat. Vitronectin, fibronectin, and RGD-containing peptides did not induce morphological changes in neurons or act as substrates for adhesion. The ability of Tat to induce morphological changes and promote adhesion was independent of the ability of Tat to transactivate HIV gene expression. Our results suggest that extracellular Tat protein most likely alters neuronal morphology and mediates adhesion by acting in a manner similar to an extracellular matrix protein.

Background: The development of coronary aneurysms as sequelae of Kawasaki disease can result in myocardial ischemia, infarction, and sudden death. Traditionally, these patients have undergone coronary angiography and nuclear stress imaging for risk stratification and follow-up. However, angiography is invasive, and both modalities expose the patient to repeated radiation, which is an important issue in children. The purpose of this study was to determine the feasibility of performing exercise stress echocardiography in children diagnosed with coronary abnormalities secondary to Kawasaki disease., Methods and Results: Treadmill exercise stress echocardiographic studies were performed in 28 children ages 6 to 16 years. All had acute Kawasaki disease 1 to 10 years before study, and coronary artery abnormalities were identified during previous echocardiographic imaging. Patients were exercised using a standard Bruce protocol. Transthoracic echocardiographic images, obtained in the parasternal long, short, apical two- and four-chamber views immediately before and after exercise, were digitized for review and analysis. In baseline studies before exercise, wall motion abnormalities were identified in 2 patients; these segments became normal with exercise. Two patients developed new exercise-induced wall motion abnormalities that corresponded to angiographically defined critical stenosis of the left anterior descending coronary artery. No patients had resting or exercise-induced ECG evidence of ischemia. There were no adverse reactions, and 26 of 28 patients had normal exercise tolerance., Conclusions: Among patients with coronary artery involvement resulting from Kawasaki disease, exercise stress echocardiography is a safe, noninvasive procedure and may identify children with myocardial ischemia that was not detected with ECG stress test alone.

Objectives: The aim of this study was to retrospectively evaluate the sensitivity of noninvasive surveillance (physical examination, echocardiography) of rejection in accurately predicting histologically documented rejection episodes. Additionally, the usefulness of routine scheduled biopsy and its safety in pediatric patients was explored., Background: Endomyocardial biopsy has been utilized as the standard for rejection surveillance after heart transplantation in adults, but its role in documenting clinically suspected rejection and in routine surveillance of pediatric patients has not been agreed upon., Methods: Heart transplantation was performed in 14 neonates and 21 children. The immunosuppressive regimen consisted of cyclosporine, azathioprine and prednisone. All patients underwent routine noninvasive rejection surveillance that included clinical examination and echocardiography. In the neonates, biopsy was performed quarterly beginning 6 months after transplantation, after cessation of prednisone therapy. In the children, biopsy was performed 15 times in the 1st year. A minimum of five biopsy samples were interpreted using the Working Formulation for Heart Transplant Rejection., Results: In the neonates, 37 biopsies were performed. Evidence of rejection was present in only three biopsy samples obtained during eight episodes (38%) of clinically suspected rejection. In 29 biopsies performed when rejection was not clinically suspected, each biopsy was free of cellular infiltrate. In the children, 291 biopsies were performed. Evidence of rejection was present in only seven biopsies (41%) from 17 episodes of clinically suspected rejection. Cellular rejection was discovered during routine rejection surveillance biopsies in asymptomatic patients in 23 (8.4%) of 274 biopsies., Conclusions: In neonates with clinically suspected rejection, endomyocardial biopsy identified which patients did not require rejection therapy. Endomyocardial biopsy surveillance did not detect any unsuspected cases of rejection. In children, noninvasive rejection surveillance was less reliable even in asymptomatic patients, suggesting that periodic endomyocardial biopsy should be utilized.

Aortic allograft conduits and valves frequently undergo calcific degeneration. To study this problem, a rat subdermal model of nonvalved aortic wall allograft calcification was characterized, and experimental studies were carried out to test the hypothesis that aortic allograft preincubation in either amino-propanehydroxydiphosphonate (APDP) or AlCl3 would inhibit calcification in a rat subdermal model. Fresh thoracic aortas were harvested under sterile conditions from male Sprague-Dawley rats (350-400 g). APDP aortas were preincubated immediately in either 4 x 10(-3) mol/l, 4 x 10(-4) mol/l, or 4 x 10(-5) mol/l [14C] APDP (37 degrees C, pH 7.4) and controls were incubated in 0.05 mol/l HEPES buffer (pH 7.4, 37 degrees C, 30 min). Al3+ aortas were preincubated in either 10(-1) mol/l, 10(-2) mol/l, or 10(-3) mol/l AlCl3. Pretreated aortas were next implanted subdermally in weanling rats (3-week-old, male, Sprague-Dawley, 50-60 g) and retrieved after 21 days. Control explants retrieved at intervals up to 21 days demonstrated progressive calcification with bulk aortic allograft Ca2+ levels increasing from a preimplant value of 0.8 +/- 0.1 micrograms/mg to 129.8 +/- 12.9 micrograms/mg by 21 days. Light microscopy revealed that much of the calcium deposition was associated with elastin. Calcification was significantly inhibited in the 4 x 10(-3) mol/l and 4 x 10(-4) mol/l APDP preincubated groups was observed (Ca2+ = 0.70 +/- 0.15 micrograms/mg, 36.6 +/- 19.8 micrograms/mg, respectively versus 117.2 +/- 24.3 micrograms/mg, control). Inhibition of calcification in the groups preincubated in the two most concentrated AlCl3 solutions (Ca2+ = 13.9 +/- 4.9 micrograms/mg [10(-2) mol/l AlCl3], 36.6 +/- 7.1 micrograms/mg [10(-3) mol/l AlCl3], 171.0 +/- 13.2 micrograms/mg [control]) was also demonstrated. No adverse effects of either pretreatment, APDP, or AlCl3 were noted on bone or overall somatic growth.

Calcification (CALC) is the most frequent cause of failure in bioprosthetic heart valves (BHV) fabricated from glutaraldehyde pretreated porcine aortic valve or bovine pericardium. Site specific controlled administration of ethanehydroxy diphosphonate (EHDP), using numerous carriers, has been successful in inhibiting CALC of BHV tissue in an accelerated rat subdermal model, without adverse effects on serum calcium, bone development, or overall somatic growth. The current study was designed to evaluate refillable reservoir devices fabricated from polyurethane (Biomer Woburn, MA) with regard to their transport properties relative to EHDP. The refillable reservoirs were evaluated for EHDP release in vitro at 22 degrees C (under perfect sink conditions) into both a physiologic receptor phase (N-2 hydroxyethylpiperazine-N'-2-ethanesulfonic acid buffer, pH = 7.4) with (1.5 mM) or without Ca2+ present. Transport parameters for EHDP diffusion through the polyurethane membranes used to fabricate the reservoirs were significantly different for the two receptor phases evaluated. The mean diffusion coefficients (D) for EHDP through the polyurethane membrane into each receptor phase were not significantly different. However, an approximately 3.5-fold reduction was observed in the mean value of the partition coefficient (K) for EHDP when EHDP was evaluated for release into a receptor phase that contained 1.5 mM Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)

Fe3+ preincubation has been shown to inhibit pathologic calcification of glutaraldehyde preserved bovine pericardium (GPBP) in the short-term rat subdermal model (21 days). This study was designed to test the long-term anticalcification efficacy of Fe3+ in the same model. Glutaraldehyde preserved bovine pericardium was preincubated (1 hr, 25 degrees C) in 0.1M FeCl3, 0.01M FeCl3, or 0.05M HEPES, then implanted subdermally in weanling male rats (40-60 gm) for 21, 60, 90, and 120 days. At explant, Fe3+ and Ca2+ levels were measured by atomic absorption spectroscopy. Fe3+ effectively inhibited calcification in both experimental groups compared to control through the longest implant (Ca2+ levels, 120 day implant: 0.1M FeCl3 = 46.85 +/- 17.45 micrograms/mg; 0.01M FeCl3 = 17.31 +/- 7.38 micrograms/mg; control = 258.04 +/- 15.71). Measurement of explanted GPBP Fe3+ levels showed that tissue Fe3+ levels of at least 7.28 +/- 0.70 micrograms/mg were required to effectively inhibit calcification after a 120-day implant. There was no evidence of Fe3+ impairment of rat growth. In conclusion, Fe3+ pretreatment of GPBP significantly inhibited calcification after long-term (120 day) rat subdermal implant.

In the present study, the authors investigated the mechanism by which Al3+ preincubations inhibited the pathologic calcification of glutaraldehyde-pretreated bovine pericardium (GPBP) implanted subdermally in rats. The concentration dependency of the Al3+ anticalcification effect was compared with that of other trivalent metal ions (Fe3+, Ga3+, La3+) known to interact with calcium phosphates. In vitro incubations of GPBP were carried out in AlCl3 (10(-3) mol/l [molar] to 10(-1) mol/l) to ascertain both the optimal conditions for uptake of Al3+ and the time course of Al3+ dissociation. Al3+ uptake by GPBP was concentration dependent and occurred rapidly, with tissue levels after 1 hour not differing significantly from those after 72 hours of incubation. Analyses of GPBP samples preincubated in AlCl3 (0.1 mol/l, 24 hours) showed that more than 75% of the Al3+ remained tightly bound after 60 days' in vitro release at 37 degrees C, pH 7.4. Preincubations of GPBP in AlCl3 significantly inhibited calcification after subdermal implantation in rats for 60 days (Ca++ = 5.1 +/- 0.9 microgram/mg, 11.5 +/- 4.6 micrograms/mg, 70.3 +/- 23.0 micrograms/mg, mean +/- standard error [SE], for 10(-1) mol/l, 10(-2) mol/l, 10(-3) mol/l AlCl3, respectively), compared with controls (Ca++ = 110.0 +/- 9.3 micrograms/mg). All animals were free of Al3(+)-mediated adverse effects on bone, as determined by light microscopic evaluation of femoral epiphyseal growth plates. Transmission electron microscopy coupled with electron energy loss spectroscopy (EELS) of GPBP incubated in 10(-1) mol l AlCl3 for 24 hours demonstrated discrete Al3+ localization in the sarcolemma and cytoplasmic and nuclear membranes of devitalized pericardial connective tissue cells at intracellular sites coincident with phosphorus loci. Similar intracellular localization remained prominent in explants removed after 60 days; no calcific deposits were noted in these specimens. Preincubations in Fe3+ but not Ga3+ and La3+ solutions yielded significant inhibition of GPBP calcification, which did not differ significantly from that provided by Al3- and had a comparable concentration dependency. Light microscopic examination (Prussian blue staining) and EELS of FeCl3-preincubated explants demonstrated Fe3+ localization within devitalized GPBP connective tissue cells. The authors conclude that Al3+ and Fe3+ significantly inhibit the pathologic mineralization of glutaraldehyde-pretreated bovine pericardium by mechanisms that are likely related to the high affinity of these cations for membrane associated and other intracellular phosphorus loci.

AI3+ preincubation has been shown in 21 and 60 day implants to inhibit calcification of glutaraldehyde preserved bovine pericardium (GPBP) in the rat subdermal model. This study was designed to assess the long-term anticalcification efficacy of GPBP AI3+ preincubation. Rat (50-60 gm, male, CD Sprague-Dawley) subdermal implants of GPBP, pretreated with 0.01 M or 0.1 M AICI3, were carried out for 21, 60, 90, and 120 days. Each explanted GPBP was analyzed for Ca2+ by atomic absorption spectroscopy and for AI3+ by atomic absorption spectroscopy or neutron activation irradiation. Results showed profound long-term (implant duration 120 days) inhibition of calcification after GPBP preincubation in 0.1 M AICI3 (Ca2+ = 21.8 +/- 12.6 micrograms/mg), compared to control (Ca2+ = 329.0 +/- 20.3 micrograms/mg). After preincubation in 0.1 M AICI3 and 21 day rat subdermal implantation, GPBP AI3+ levels declined from 9033 +/- 680 micrograms/g (control = 6.3 +/- 3.7 micrograms/g) to 2700 +/- 156 micrograms/g; however, there was no further significant decline in GPBP AI3+ levels after long-term implantation of 120 days (2618.4 +/- 349 micrograms/g). The authors conclude that GPBP preincubation in 0.1 M AICI3 markedly inhibited pathologic calcification to 7% of control values in the rat model after long-term (120 day) subdermal implantation.

Al+++ preincubation has been shown to inhibit calcification of glutaraldehyde pretreated bovine pericardium calcification in the rat subdermal model. This study was designed to assess in vitro the Al+++ (10(-1) M, 10(-2) M, 10(-3) M preincubations) binding characteristics of glutaraldehyde pretreated bovine pericardium. In vivo studies assessed the ability of AlCl3 (10(-1) M, 10(-2) M, 10(-3) M) preincubations to inhibit calcification after 21 and 60 days in the rat subdermal model. Other in vivo studies investigated the ability of other metallic cations (Fe+++, La+++, and Ga+++) used as a pretreatment to inhibit glutaraldehyde pretreated bovine pericardium calcification after a 21 day rat subdermal implant. Lyophylized glutaraldehyde pretreated bovine pericardium samples were analyzed for Al+++ by neutron activation. In vitro results showed the greatest glutaraldehyde pretreated bovine pericardium Al+++ uptake in specimens incubated in 0.1M AlCl3. Maximal Al+++ uptake occurred by 1 hour. Glutaraldehyde pretreated bovine pericardium Al+++ levels after incubation in 10(-1) M, 10(-2) M, and 10(-3) M AlCl3 for 1 hour were 351.4 +/- 15.8 nM/mg, 96.4 +/- 17.4 nM/mg, and 24.6 +/- 4.9 nM/mg, respectively versus 394.5 +/- 48.0 nM/mg, 105.3 +/- 2.3 nM/mg, 40.0 +/- 8.8 nM/mg, respectively for 3 days. In vivo 21 day rat (50-60 g, male, Sprague-Dawley) subdermal implants of 0.1 M AlCl3, FeCl3, FeCl3 plus citrate, LaCl3, and GaNO3 pretreated glutaraldehyde pretreated bovine pericardium showed calcification inhibition by Al+++, Fe+++, and Fe+++ plus citrate (Ca++ = 5.5 +/- 0.2 micrograms/mg, 13.6 +/- 4.6 micrograms/mg, 5.9 +/- 1.7 micrograms/mg, respectively) compared to control (Ca++ = 63.6 +/- 5.7 micrograms/mg).(ABSTRACT TRUNCATED AT 250 WORDS)

Calcification is frequently noted in valved and non-valved aortic homografts, predominantly in the aortic wall portion. This study was designed to assess the individual anticalcification effects of the trivalent cation, aluminum (AI ), and the compound aminopropanehydroxydiphosphonate (APDP) when used to pretreat aortic wall homograft tissue before subdermal implantation in the rat model. Thoracic aortas of male rats (CD, Sprague-Dawley, 350 to 400 g) were harvested distal to the aortic valve and incubated in the following solutions: 1) APDP (0.004 M), 2) APDP (0.004 M) + glutaraldehyde (GLUT) (0.02 M), 3) GLUT (0.02 M), 4) ALCL3 (0.01 M), 5) HCL (0.001 M), and 6) HEPES (0.05 M). The homograft tissue was then implanted subcutaneously for 21 days in weanling male rats (50 to 60 gm) of the same strain. Explant results showed that calcification (CALC) was markedly inhibited in the APDP and 0.01 M ALCL3 groups, compared to the control and GLUT pretreated groups. No diphosphonate or aluminum related side effects were seen.

Calcification is the principal mode of failure of bioprosthetic heart valves (BPHV) fabricated from glutaraldehyde-pretreated porcine aortic valves or bovine pericardium. Covalent binding of aminopropanehydroxy-diphosphonate (APDP) to residual glutaraldehyde in pericardial BPHV tissue was studied as an approach for the inhibition of calcification. BPHV tissue was preincubated in 0.14 M APDP at pH 7.4, 9.0, and 11.0 for various durations (1 hour to 8 days). The need for NaBH4 stabilization of the tissue-bound APDP was also examined in vitro. The bound APDP was determined using 14C-labeled APDP. APDP uptake was dependent on incubation duration and pH. Calcification of APDP-pretreated BPHV was studied using 21-day rat subdermal implants. Calcification inhibition was directly related to the amount of tissue APDP incorporation. Inhibition of calcification to less than 15% of control was achieved with a concentration of bound APDP of greater than or equal to 30 nM/mg dry tissue with more than 1 hour of incubation at pH 11.0 (bound APDP, 33.55 nM/mg; BPHV calcium content = 3.1 +/- 0.9 micrograms/mg). No adverse effects such as rat growth inhibition or disruption of bone architecture were observed after any treatment. Additionally, in vitro, NaBH4 stabilized tissue-bound APDP. In conclusion, APDP covalently bound to residual aldehyde functions markedly inhibited calcification of BPHV tissue. This inhibition was dependent on the amount of APDP incorporated. NaBH4 stabilized APDP-glutaraldehyde covalent bonds.

To date, the clinical usefulness of bioprosthetic heart valves (BPV) fabricated from glutaraldehyde pretreated porcine aortic valves or bovine pericardium has been limited because leaflet calcification (CALC) leads to valvular stenosis and/or regurgitation and subsequent valve failure. The present study was designed to test the hypothesis that preincubation of glutaraldehyde pretreated pericardial BPV leaflets in a solution containing the trivalent cation, AL , inhibits BPV calcification. BPV tissue was preincubated in 0.1 M ALCL3 for 24 hours (T = 25 degrees C), then subdermally implanted in rats (weanling, male, CD, Sprague-Dawley) for 21 days. Compared to the control group (tissue Ca++ = 143.81 +/- 25.49 micrograms/mg), calcification was markedly inhibited in the group pretreated with AL (tissue Ca++ = 4.1 +/- 1.03 micrograms/mg) after a 21 day implant. No adverse effects on rat growth or bone morphology were detected. It is concluded that the trivalent cation AL provided a marked anticalcification effect for BPV tissue implanted subdermally in the rat for 21 days.

Quinidine syncope and factors associated with it are well known among adult patients treated for cardiac arrhythmias. To define factors that may influence the occurrence of syncope in children taking quinidine, the clinical, anatomic, electrocardiographic, roentgenographic and pharmacologic data were compared in six patients with syncope (Group A) and 22 patients without syncope (Group B). There was a significant (chi-square = 10.2, p = 0.001) relation between heart disease and quinidine syncope: all six Group A (syncopal) patients had heart disease whereas 15 of the 22 Group B (non-syncopal) patients had no structural heart disease. In contrast, no significant difference was noted between Group A and Group B patients in mean age (11.4 versus 11.4 years), mean quinidine serum concentration (2.9 versus 2.3 micrograms/ml), mean corrected QT interval before quinidine (0.43 versus 0.40 second) or mean corrected QT interval during quinidine therapy (0.46 versus 0.46 second) or between those taking digitalis and those not. Two of the six Group A (syncopal) patients died during therapy, one 6 days after initiating therapy and one suddenly at home 6 months after beginning quinidine. Another two of the six Group A patients exhibited hypokalemia (both 2.9 mEq/liter) at the time of syncope, 2 weeks and 6 months, respectively, after initiation of quinidine therapy; both survived. Syncope occurred within 8 days of initiation of quinidine therapy in three of the six patients. Sustained ventricular tachycardia was observed during quinidine associated arrhythmia in three of six patients with syncope; nonsustained ventricular tachycardia or complex ventricular ectopic activity while on this therapy was observed before syncope in the other three patients in Group A.(ABSTRACT TRUNCATED AT 250 WORDS)