Safety of intracoronary administration of c-myc antisense oligomers after percutaneous transluminal coronary angioplasty (PTCA).

We wished to assess the clinical safety and pharmacokinetics of ascending doses of a synthetic oligodeoxynucleotide (LR-3280) administered after coronary angioplasty. Antisense oligodeoxynucleotides designed to hybridize with target messenger ribonucleic acid (mRNA) in a complementary fashion to inhibit the expression of corresponding protein also have the ability to bind to extracellular growth factors. LR-3280 has been shown to reduce c-myc expression, inhibit growth and collagen biosynthesis in human vascular cells, and reduce neointimal formation in animal models of vascular injury. After successful percutaneous transluminal coronary angioplasty (PTCA), 78 patients were randomized to receive either standard care (n = 26) or standard care and escalating doses of LR-3280 (n = 52) (doses from 1 to 24 mg), administered into target vessel through a guiding catheter. Overall safety was evaluated by clinical adverse events, laboratory tests, and electrocardiograms. Patency was evaluated by quantitative coronary angiography. There were no clinically significant differences between treated and control patients. No adverse effects of LR-3280 on the patency of dilated coronary arteries were observed. Pharmacokinetic data revealed that peak plasma concentrations of LR-3280 occurred at 1 minute over the studied dose range and rapidly decreased after approximately1 hour, with little LR-3280 detected in the urine between 0-6 hours and 12-24 hours. The intracoronary administration of LR-3280 is well tolerated at doses up to 24 mg and produces no adverse effects in dilated coronary arteries. These results provide the basis for the evaluation of local delivery of this phosphorothioate oligodeoxynucleotide for the prevention of human vasculoproliferative disease.

Balloon optimization versus stent study (BOSS): provisional stenting and early recoil after balloon angioplasty.

"Optimal" percutaneous transluminal coronary angioplasty (PTCA) may have a late restenosis rate similar to stenting. We sought to assess short- and long-term results of a provisional stenting/optimal PTCA approach compared with elective stenting in a prospective, randomized study. A total of 97 patients with discrete, de novo lesions in native coronary arteries > or =3 mm in diameter were randomized 2:1 in PTCA with prolonged perfusion balloon inflation (n = 66) versus elective stenting (n = 31). Recoil after PTCA was assessed by routine delayed angiograms (5 and 20 minutes). Cross over to stent was allowed for an inadequate result; there was no on-line quantitative angiography. An independent core angiographic laboratory assessed all results and evaluated the adequacy of the subjective interpretation. Within the PTCA arm, there were 24 (36%) crossovers to stenting (5 of 24 [21%] due to recoil), whereas 2 stents could not be delivered to the lesion and crossed over to PTCA. As assessed by quantitative angiography, baseline reference vessel diameters were similar between the PTCA and stent groups. The immediate lumen diameter achieved with PTCA was smaller than that achieved with stenting (2.18+/-0.49 vs. 2.44+/-0.38 mm, respectively, p = 0.01). There were no differences in angiographic results between elective and crossover stenting and there were no in-hospital complications in any patient. Target lesion revascularization at 8 months was 19% (n = 6) in the elective stent arm versus 21% (n = 14) in the PTCA arm, p = NS; respective rates in PTCA alone and crossed over-to-stent subsets were 23% (n = 10) versus 17% (n = 4), p = NS. Angiographic restenosis was 47% after elective stenting versus 38% after PTCA (intention to treat), p = NS. By received treatment, it was 41% (11 of 27) in the group treated with the PTCA versus 33% (5 of 15) in the crossover-to-stent arm (p = NS). Thus, provisional stenting can be safely performed in the treatment of discrete, native de novo lesions. Early recoil after PTCA cannot be reliably assessed without quantitative angiography.

Dilated cardiomyopathy in homozygous myosin-binding protein-C mutant mice.

To elucidate the role of cardiac myosin-binding protein-C (MyBP-C) in myocardial structure and function, we have produced mice expressing altered forms of this sarcomere protein. The engineered mutations encode truncated forms of MyBP-C in which the cardiac myosin heavy chain-binding and titin-binding domain has been replaced with novel amino acid residues. Analogous heterozygous defects in humans cause hypertrophic cardiomyopathy. Mice that are homozygous for the mutated MyBP-C alleles express less than 10% of truncated protein in M-bands of otherwise normal sarcomeres. Homozygous mice bearing mutated MyBP-C alleles are viable but exhibit neonatal onset of a progressive dilated cardiomyopathy with prominent histopathology of myocyte hypertrophy, myofibrillar disarray, fibrosis, and dystrophic calcification. Echocardiography of homozygous mutant mice showed left ventricular dilation and reduced contractile function at birth; myocardial hypertrophy increased as the animals matured. Left-ventricular pressure-volume analyses in adult homozygous mutant mice demonstrated depressed systolic contractility with diastolic dysfunction. These data revise our understanding of the role that MyBP-C plays in myofibrillogenesis during cardiac development and indicate the importance of this protein for long-term sarcomere function and normal cardiac morphology. We also propose that mice bearing homozygous familial hypertrophic cardiomyopathy-causing mutations may provide useful tools for predicting the severity of disease that these mutations will cause in humans.

Slow tonic muscle fibers in the thyroarytenoid muscles of human vocal folds; a possible specialization for speech.

Most of the sounds of human speech are produced by vibration of the vocal folds, yet the biomechanics and control of these vibrations are poorly understood. In this study the muscle within the vocal fold, the thyroarytenoid muscle (TA), was examined for the presence and distribution of slow tonic muscle fibers (STF), a rare muscle fiber type with unique contraction properties. Nine human TAs were frozen and serially sectioned in the frontal plane. The presence and distribution pattern of STF in each TA were examined by immunofluorescence microscopy using the monoclonal antibodies (mAb) ALD-19 and ALD-58 which react with the slow tonic myosin heavy chain (MyHC) isoform. In addition, TA muscle samples from adjacent frozen sections were also examined for slow tonic MyHC isoform by electrophoretic immunoblotting. STF were detected in all nine TAs and the presence of slow tonic MyHC isoform was confirmed in the immunoblots. The STF were distributed predominantly in the medial aspect of the TA, a distinct muscle compartment called the vocalis which is the vibrating part of the vocal fold. STF do not contract with a twitch like most muscle fibers, instead, their contractions are prolonged, stable, precisely controlled, and fatigue resistant. The human voice is characterized by a stable sound with a wide frequency spectrum that can be precisely modulated and the STF may contribute to this ability. At present, the evidence suggests that STF are not presented in the vocal folds of other mammals (including other primates), therefore STF may be a unique human specialization for speech.

Identification of the A-band localization domain of myosin binding proteins C and H (MyBP-C, MyBP-H) in skeletal muscle.

Although major constituents of the thick filaments of vertebrate striated muscles, the myosin binding proteins (MyBP-C and MyBP-H) are still of uncertain function. Distributed in the cross-bridge bearing zone of the A-bands of myofibrils, in a series of transverse 43 nm stripes, the proteins are constructed of a tandem series of small globular domains, each composed of approximately 90-100 amino acids, which have sequence similarities to either the C2-set of immunoglobulins (IgC2) and the fibronectin type III (FnIII) motifs. MyBP-C is composed of ten globular domains ( approximately 130 kDa) whereas MyBP-H is smaller ( approximately 58 kDa) and consists of a unique N-terminal segment followed by four globular domains, the order of which is identical to that of MyBP-C (FnIII-IgC2-FnIII-IgC2). To improve our understanding of this protein family we have characterized the domains in each of these two proteins which are required for targeting the proteins to their native site(s) in the sarcomere during myogenesis. Cultures of skeletal muscle myoblasts were transfected with expression plasmids encoding mutant constructs of the MyBPs bearing an N-terminal myc epitope, and their localization to the A-band examined by immunofluorescence microscopy. Based on the clarity and intensity of the myc A-band signals we concluded that constructs encoding the four C-terminal motifs of MyBP-C and MyBP-H ( approximately 360 amino acids) were all that was necessary to efficiently localize each of these peptides to the A-band. Truncation mutants lacking one of these 4 domains were less efficiently targeted to the C-zone of the sarcomere. Deletion of the last C-terminal motif of MyBP-H, its myosin binding domain, abolished all localization to the A-band. A chimeric construct, HU-3C10, in which the C-terminal motif of MyBP-H was replaced by the myosin binding domain of MyBP-C, efficiently localized to the A-band. Taken together, these observations indicate that MyBP-C and MyBP-H are localized to the A-band by the same C-terminal domain, composed of two IgC2 and two FnIII motifs. A model has been proposed for the interaction and positioning of the MyBPs in the thick filament through a ternary complex of the four C-terminal motifs with the myosin rods and titin.

The interface between MyBP-C and myosin: site-directed mutagenesis of the CX myosin-binding domain of MyBP-C.

Myosin-binding protein-C (MyBP-C or C-protein) is a ca. 130 kDa protein present in the thick filaments of all vertebrate striated muscle. The protein contains ten domains, each of ca. 90-100 amino acids; seven are members of the IgI family of proteins, three of the fibronectin type III family. The motifs are arranged in the following order (from N- to C-terminus): Ig-Ig-Ig-Ig-Ig-Fn-Fn-Ig-Fn-Ig. The C-terminal Ig motif (domain X or CX) contains its light meromyosin-binding site. A recombinant form of CX, beginning at Met-1027, exhibits saturable binding to myosin with an affinity comparable to the C-terminal 13 kDa chymotryptic fragment of native MyBP-C. To identify the surface in CX involved in its interaction with myosin, nine site-directed mutants (R37E, K43E, N49D, E52R, D56K, R73E, R74E, G80D and R103E) were constructed. Using a new assay for assessing the binding of CX with the light meromyosin (LMM) portion of myosin, we demonstrate that recombinant CX, just as the full-length protein, is able to facilitate LMM polymerization. Moreover, we show that residues Arg-37, Glu-52, Asp-56, Arg-73, and Arg-74 are involved in this interaction with the myosin rod. All of these amino acids interact with negatively charged residues of LMM, since the mutants R37E, R73E and R74E are unable to bind myosin, whereas E52R and D56K bind myosin with higher affinity than wild-type CX. Residues Lys-43 and Arg-103 show a small but significant influence on the binding reaction; residues Asn-49 and Gly-80 seem not to be involved in this interaction. Based on these data, a model is proposed for the interaction between MyBP-C CX and myosin filaments. In this model, CX interacts with four molecules of LMM at four different sites of the binding protein, thus explaining the effects of MyBP-C on the critical concentration of myosin polymerization.

[Paraneoplastic neuropathy with positive anti-Hu]. / Neuropatía paraneoplásica con anti-Hu positivo.

The case of a 72-year-old woman presenting sensory neuropathy and anti-Hu antibodies is reported. She was admitted in November 1995 with a one year history of sensory neuropathy. Her first symptoms were painful numbness and dysesthesias in both feet. She experienced progression of the sensory symptoms affecting upper limbs, and clumsiness of gait. One month before admission she complained of diminished strength in both hands. The neurologic examination showed anicocoric fixed pupils, with no reaction to light; convergence miosis was evident in the right eye (Argyll-Robertson pupil). In the lower limbs she had very mild distal weakness, and tendon reflexes were universally abolished. Pin and touch sensation, position sense and pallesthesia were absent in all four limbs. Romberg test was elicited, and a tabetic gait was patent. Pseudoathetotic movements were observed in hands and feet. An ulcer was present in the fifth finger of the right foot. Routine blood biochemistry and hematology showed a ESR of 105 and an increased IgG in the immune-electrophoretic run. Neurophysiologic evaluation disclosed a mild demyelinating neuropathy. Positive anti-Hu antibodies were found in the serum (Western blot - Athena Diagnostics); CSF was normal but not tested for anit-Hu. An abdominal CT scan disclosed multiple hypodense nodules in liver, right adrenal gland and peritoneum. A chest CT scan showed a hyperdense mass in the lower right pulmonary lobe and enlarged retrocava-pretracheal lymph nodes. A biopsy of the peritoneal nodule was performed, showing a metastatic small cell carcinoma. The patient died eight days after discharge. Although multiple organs were affected, she was independent until death, showing an indolent clinical course.

Rheolytic thrombectomy of chronic coronary occlusion.

Percutaneous intervention in patients with intracoronary thrombus continues to pose a significant clinical challenge. In this report, we describe the successful treatment of a 44-year-old patient with an extensive chronic thrombotic occlusion of the right coronary artery using a rheolytic thrombectomy catheter. Despite angiographic documentation of coronary thrombosis 104 days prior to treatment and a voluminous thrombus burden (60 mm in length x 3 mm in diameter), rapid recanalization was accomplished with this device without embolic complications. At 1 year clinical follow-up, the patient has remained symptom free. The design of this novel device and its mechanism of action are described.

One-year follow-up of the Stent Restenosis (STRESS I) Study.

We present the completed 1-year follow-up results of the original Stent Restenosis Study (STRESS I), in which 407 patients with symptomatic ischemic heart disease and new lesions of the native coronary circulation were randomly assigned to treatment with either the Palmaz-Schatz coronary stent or conventional percutaneous transluminal coronary angioplasty (PTCA). The present study compares the safety of elective stenting to balloon angioplasty (PTCA) in terms of freedom from clinical events up to 1 year after treatment. Patients were enrolled and treated from January 1991 through February 1993, and follow-up data were collected and verified until July 1995. Ninety-seven percent of all patients had complete follow-up (deceased or alive with known clinical status) beyond 8 months, and 94% beyond 11 months. Anginal status between 9 to 15 months postprocedure was available for 78% of patients. At 1 year, 154 patients (75%) assigned to stent implantation and 141 (70%) to PTCA were free of all clinical events (death, myocardial infarction, or any revascularization procedure), and 162 stent patients (79%) and 149 PTCA patients (74%) were free from death, myocardial infarction, or target lesion revascularization. Symptom-driven target lesion revascularization occurred in 12% of the stent group versus 17% of the PTCA group. None of these differences in clinical events was statistically significant. Only 2 patients in the stent group and 7 in the PTCA group had a first event after 239 days, and freedom from angina at 1 year was reported in equal frequency in both groups (84%). There appear to be no late adverse effects of stent implantation. However, these results are limited by low statistical power, narrow patient selection, and the anticoagulation regimen used in the early experience with this device.

Efficacy of coronary stenting versus balloon angioplasty in small coronary arteries. Stent Restenosis Study (STRESS) Investigators.

OBJECTIVES: The goal of this study was to compare the efficacy of elective stent implantation and balloon angioplasty for new lesions in small coronary arteries. BACKGROUND: Palmaz-Schatz stents have been designed and approved by the Food and Drug Administration for use in coronary arteries with diameters > or = 3.0 mm. The efficacy of elective stent placement in smaller vessels has not been determined. METHODS: By quantitative coronary angiography, 331 patients in the Stent Restenosis Study (STRESS) I-II were determined to have a reference vessel < 3.0 mm in diameter. Of these, 163 patients were randomly assigned to stenting (mean diameter 2.69 +/- 0.21 mm), and 168 patients were assigned to angioplasty (mean diameter 2.64 +/- 0.24 mm). The primary end point was restenosis, defined as > or = 50% diameter stenosis at 6-month follow-up angiography. Clinical event rates at 1 year were assessed. RESULTS: Baseline clinical and angiographic characteristics were similar in the two groups. Procedural success was achieved in 100% of patients assigned to stenting and in 92% of patients assigned to angioplasty (p < 0.001). Abrupt closure within 30 days occurred in 3.6% of patients in both groups. Compared with angioplasty, stenting conferred a significantly larger postprocedural lumen diameter (2.26 vs. 1.80 mm, p < 0.001) and a larger lumen at 6 months (1.54 vs. 1.27 mm, p < 0.001). Restenosis (> or = 50% diameter stenosis at follow-up) occurred in 34% of patients assigned to stenting and in 55% of patients assigned to angioplasty (p < 0.001). At 1 year, event-free survival was achieved in 78% of the stent group and in 67% of the angioplasty group (p = 0.019). CONCLUSIONS: These findings suggest that elective stent placement provides superior angiographic and clinical outcomes than balloon angioplasty in vessels slightly smaller than 3 mm.

Stent placement compared with balloon angioplasty for obstructed coronary bypass grafts. Saphenous Vein De Novo Trial Investigators.

BACKGROUND: Treatment of stenosis in saphenous-vein grafts after coronary-artery bypass surgery is a difficult challenge. The purpose of this study was to compare the effects of stent placement with those of balloon angioplasty on clinical and angiographic outcomes in patients with obstructive disease of saphenous-vein grafts. METHODS: A total of 220 patients with new lesions in aortocoronary-venous bypass grafts were randomly assigned to placement of Palmaz-Schatz stents or standard balloon angioplasty. Coronary angiography was performed during the index procedure and six months later. RESULTS: As compared with the patients assigned to angioplasty, those assigned to stenting had a higher rate of procedural efficacy, defined as a reduction in stenosis to less than 50 percent of the vessel diameter without a major cardiac complication (92 percent vs. 69 percent, P<0.001), but they had more frequent hemorrhagic complications (17 percent vs. 5 percent, P<0.01). Patients in the stent group had a larger mean (+/-SD) increase in luminal diameter immediately after the procedure (1.92+/-0.30 mm, as compared with 1.21+/-0.37 mm in the angioplasty group; P<0.001) and a greater mean net gain in luminal diameter at six months (0.85+/-0.96 vs. 0.54+/-0.91 mm, P=0.002). Restenosis occurred in 37 percent of the patients in the stent group and in 46 percent of the patients in the angioplasty group (P=0.24). The outcome in terms of freedom from death, myocardial infarction, repeated bypass surgery, or revascularization of the target lesion was significantly better in the stent group (73 percent vs. 58 percent, P = 0.03). CONCLUSIONS: As compared with balloon angioplasty, stenting of selected venous bypass-graft lesions resulted in superior procedural outcomes, a larger gain in luminal diameter, and a reduction in major cardiac events. However, there was no significant benefit in the rate of angiographic restenosis, which was the primary end point of the study.

Isoform-specific interaction of the myosin-binding proteins (MyBPs) with skeletal and cardiac myosin is a property of the C-terminal immunoglobulin domain.

Full-length cDNAs encoding chicken and human skeletal MyBP-H and MyBP-C have been isolated and sequenced (1-5). All are members of a protein family with repetitive immunoglobulin C2 and fibronectin type III motifs. The myosin binding domain was mapped to a single immunoglobulin motif in cardiac MyBP-C and skeletal MyBP-H. Limited alpha-chymotryptic digestion of cardiac MyBP-C generated three peptides, similar in relative mobility to those of skeletal MyBP-C: approximately 100, 40, and 15 kDa. Tryptic digestion of MyBP-H yielded two peptides: approximately 50 and 14 kDa. Partial amino acid sequences proved that the 15- and 14-kDa fragments are located at the C termini of cardiac MyBP-C and skeletal MyBP-H, respectively. Only the 14- and 15-kDa peptides bound to myosin. Thus, the myosin binding site in all three proteins resides within an homologous, C-terminal immunoglobulin domain. Binding reactions (2) between the skeletal and cardiac MyBPs and corresponding myosin isoforms demonstrated saturable binding of the MyBP proteins and their C-terminal peptides to myosin, but there are higher limiting stoichiometries with the homologous isoform partners. Evidence is presented indicating that MyBP-H and -C compete for binding to a discrete number of sites in myosin filaments.

Skeletal muscle-specific myosin binding protein-H is expressed in Purkinje fibers of the cardiac conduction system.

Heart contraction is coordinated by conduction of electrical excitation through specialized tissues of the cardiac conduction system. By retroviral single-cell tagging and lineage analyses in the embryonic chicken heart, we have recently demonstrated that a subset of cardiac muscle cells terminally differentiates as cells of the peripheral conduction system (Purkinje fibers) and that this occurs invariably in perivascular regions of developing coronary arteries. Cis regulatory elements that function in transcriptional regulation of cells in the conducting system have been distinguished from those in contractile cardiac muscle cells; eg, 5' regulatory sequences of the desmin gene act as enhancer elements in skeletal muscle and in the conduction system but not in cardiac muscle. We hypothesize that Purkinje fiber differentiation involves a switch of the gene expression program from that characteristic of cardiac muscle to one typical of skeletal muscle. To test this hypothesis, we examined the expression of myosin binding protein-H (MyBP-H) in Purkinje fibers of chicken hearts. This unique myosin binding protein is present in skeletal but not cardiac myocytes. A site-directed polyclonal antibody (AB105) was generated against MyBP-H. Immunohistological analysis of the myocardium mapped the AB105 antigen predominantly to A bands of myofibrils within Purkinje fibers. Western blot analysis of whole extracts from the ventricular wall of adult chicken hearts revealed that the AB105 epitope was restricted to a single protein of approximately 86 kD, the same size as MyBP-H in skeletal muscle. Biochemical properties of the Purkinje fiber 86-kD protein and RNase protection analyses of its mRNA indicate that Purkinje fiber 86-kD protein is indistinguishable from skeletal muscle MyBP-H. The results provide evidence that skeletal muscle MyBP-H is expressed in a subset of cardiac muscle cells that differentiate into Purkinje fibers of the heart.

Frequency and outcome of development of coronary artery aneurysm after intracoronary stent placement and angioplasty. STRESS Trial Investigators.

Elective Palmaz-Schatz intracoronary stent implantation does not increase the risk for coronary artery aneurysm formation. Angiographic restenosis and clinical outcome are not affected by the development of a coronary artery aneurysm after percutaneous transluminal coronary artery or stent placement.

Retrospective comparative study of primary intracoronary stenting versus balloon angioplasty for acute myocardial infarction.

Balloon angioplasty has been shown to be an effective therapy for the treatment of acute myocardial infarction but is associated with a high restenosis rate, substantial early recoil, persistent thrombus and need for intracoronary thrombolysis, and a high rate of reclosure. Because many of the limitations of balloon angioplasty in the noninfarction setting are addressed by intracoronary stenting, we examined the results of primary stenting of 18 consecutive patients treated for acute myocardial infarction, and compared the results to those achieved with primary balloon angioplasty in 18 prior cases. Despite the presence of thrombus prior to angioplasty in 13 of the stented patients, no intracoronary thrombolytic therapy was required. Mean percent stenosis using quantitative coronary angiography was 17.7 +/- 10.2% after primary stenting compared with 43.7 +/- 20.3% after primary balloon angioplasty (P < .001). One stent patient who had all anticoagulant and antiplatelet therapy withdrawn early suffered subacute thrombosis. Patients were followed up to 3 yr. Complications were similar in two groups. We conclude that primary stenting for acute myocardial infarction results in superior angiographic appearance as well as resolution of thrombus without the need for routine thrombolysis, and is associated with a low complication rate and excellent short-term clinical patency.

Peripheral vascular complications after intracoronary stent placement: prevention by use of a pneumatic vascular compression device.

Peripheral vascular complications are a significant source of morbidity after coronary artery stent implantation. The goal of this study was to assess the incidence, risk factors, and management of vascular complications after stent placement. The study population consisted of 101 consecutive patients who underwent stent placement for either elective or bailout indications. All patients received a standardized anticoagulation regimen of aspirin, dipyridamole, low molecular weight dextran, heparin, and warfarin. Peripheral vascular access sites were examined daily until hospital discharge. Vascular complications occurred in 16 of 101 (16%) patients, including femoral artery pseudoaneurysm (n = 11), hematoma requiring transfusion or surgery (n = 4), and arteriovenous fistula (n = 1). Intervention was required in 14 of 16 (88%) patients with complications. These included transfusion (n = 7), ultrasound-guided compression (n = 8), and/or vascular surgery (n = 7). Length of hospital stay was prolonged in patients with complications (14 +/- 9 vs. 8 +/- 5 d, P < 0.001). The development of peripheral vascular complications did not correlate with clinical or procedural variables such as age, cardiovascular risk factors, arterial sheath size, or elective vs. bailout indication. After the introduction of a pneumatic vascular compression device (FEMOSTOP, C.A. Bard, Billerica, MA), a significant reduction in vascular complications was observed. Complications occurred in only 1 of 41 (2.4%) patients in whom the compression device was used in contrast to 13 of 58 (22.4%) patients compressed manually (P < 0.01). Thus peripheral vascular complications are frequent after coronary artery stent placement and are associated with serious morbidity and prolongation of hospital stay. These complications are significantly reduced by the use of a pneumatic vascular compression device despite intensive systemic anticoagulation.