Multicenter Pilot Study of a Serpentine Balloon-Expandable Stent (beStentTM): Acute Angiographic and Clinical Results

The beStent is a new stainless steel, balloon-expandable mesh stent which has a unique serpentine design. Rotation of the unique low stress junctions upon expansion leads to orthogonal locking of the wires, maximizing radial strength and assuring zero shortening. The stent has delineating gold markers which assure precise positioning. We aim to present the initial acute results in a pilot registry for stent evaluation. Two hundred eighty-four stents were used in a total of 217 patients (age 57.9 ± 3.10 years; 178 males; 39 females) in seven centers, for variable indications. Stents of 15-, 25-, and 35-mm length were used. The arteries treated were the left anterior descending (n = 112, 42%), circumflex (n = 54, 20.2%), right coronary (n = 95, 35.5%), left main (n = 1, 0.4%), and vein graft (n = 5, 1.9%). Lesion types were: A in 42 patients (16.5%); B1 in 53 patients (20.7%); B2 in 81 patients (31.8%); and C in 79 patients (31%). One hundred fifty-nine patients required one stent, 40 patients required two stents, and 18 patients required three or more stents. Anticoagulation protocol included procedural heparin with aspirin with/without ticlopidine. Smooth angiographie results were obtained in all cases with no plaque herniation. Acute angiographic success was obtained in 97% of the patients, and acute clinical success in 95% of the patients. Complications within 30 days were: 3 deaths (1.4%) (2 noncardiac); 2 (0.9%) myocardial infarctions; and 2 (0.9%) stent thromboses. Therefore, the beStent is useful in treatment of complex lesions of variable length and complexity, providing excellent acute results with a low complication rate, in spite of unfavorable basic clinical and angiographie characteristics.     

Biochemical parameters which may be useful in improving organ viability after storage.

Biochemical methods that accurately detect ischemic damage in livers stored by flush cooling would be useful in the efficient development of new storage solutions. This study compares UW and Collins' solutions to evaluate those biochemical parameters which may be useful in assessing the reversibility of ischemic damage and the efficiency of organ storage solutions. Livers stored in UW solution showed higher levels of adenine nucleotides at all storage times studied. This increase in adenine nucleotides averaged 29% and was statistically significant. There was also a significant increase in the NAD levels in organs stored in UW solutions; however, the ATP levels were not significantly different after storage in either solution. Storage of livers in UW solution also decreased the amount of DNA damage which occurs with storage as compared to storage in Collins' solution, becoming statistically significant after 48 hr of storage. This suggests that these biochemical parameters may be useful in designing improved storage solutions since they reflect the extent of ischemic damage to the organ and can be determined on a small section of liver taken by biopsy.     

Aminoglycoside-induced blockade of reflex activity in the isolated spinal cord from the neonatal rat

The subarachnoid injection of gentamicin into rats causes a transient flaccid paralysis of the hindlimbs lasting 1 to 5 hrs followed by a permanent flaccid paralysis which develops after 24 to 36 hrs. Although the early transient paralysis could be attributed to a pharmacologic blockade of central synaptic transmission, the mechanism of the blockade was not apparent. This study examines the effects of gentamicin and two other aminoglycoside antibiotics, kanamycin and neomycin, on reflex transmission in the isolated, hemisected spinal cord of the neonatal rat and the interaction with calcium. Gentamicin produced a concentration-dependent depression of reflex activity with a 50% inhibitory concentration of 1.6 mM at an external calcium concentration ([Ca2+]o) of 2.5 mM. Reducing the [Ca2+]o by half (i.e., to 1.25 mM) lowered the 50% inhibitory concentration of gentamicin to 0.22 mM. Gentamicin also increased the magnitude of homosynaptic depression of reflex activity in a manner qualitatively similar to that of decreasing [Ca2+]o. Lowering the [Ca2+]o potentiated the effect of gentamicin on homosynaptic depression. The actions of neomycin, kanamycin and magnesium on reflex transmission were nearly identical to those of gentamicin. These findings demonstrate that the early paralysis seen after subarachnoid injection of gentamicin may result from a central blockade of transmission. It is most likely that the site for blockade of reflex activity by gentamicin is presynaptic.     

Perfluorochemicals as US contrast agents for tumor imaging and hepatosplenography: preliminary clinical results

In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients.     

Pharmacology of the alkaloid pumiliotoxin-B. II. Possible involvement of calcium and sodium-dependent processes in nerve and skeletal muscle

The mechanism of the twitch potentiating action of pumiliotoxin-B (PTX-B), an indolizidine alkaloid from the skin of the frog Dendrobates pumilio, was studied on frog skeletal muscles. In the presence of PTX-B, a single stimulus to the muscle produced either a burst of repetitive action potentials superimposed on a depolarizing afterpotential or a single potential with a prolonged afterpotential at junctional as well as extrajunctional regions of the frog skeletal muscle fibers. The alkaloid did not cause repetitive activity in quiescent cells or spontaneous contractions. The duration of the burst of action potentials was related inversely and the amplitude and duration of postburst depolarizing after-potential was related directly to the concentration of PTX-B. The typical pattern of repetitive action potentials and postburst depolarization induced by PTX-B could be mimicked by depolarizing the muscle membrane with current pulses of long duration (150-470 ms). Lowering the external calcium or sodium concentration reduced the ability of PTX-B to initiate repetitive action potentials, whereas a low external chloride concentration had no effect. The frequency of MEPPs evoked by potassium, but not the spontaneous MEPP frequency, was increased by PTX-B, suggesting a selective effect on evoked transmitter release. PTX-B evoked repetitive EPPs in response to a single stimulus applied to the nerve, which was dependent upon the external calcium ion concentration. The amplitudes of EPPs in the train were facilitated, and their amplitude increased linearly at the lowest calcium concentration, but not at concentrations from 0.45 to 1.8 mM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Coralline hydroxyapatite bone graft substitutes: preliminary report of radiographic evaluation

A new bone graft substitute made by conversion of the calcium carbonate exoskeleton of reef-building sea coral into hydroxyapatite has recently become clinically available. The normal radiographic appearance of two forms of this material is described. In the immediate postoperative period, the exoskeletal architecture of these implants is readily appreciated. With graft incorporation over the ensuing months, their intrinsic structure is gradually lost in association with poor marginal definition. Evolving radiographic findings reflect the biocompatible nature of these implants, which provides the potential for ingrowth of native bone with preservation of the coralline scaffold, resulting in enhanced biomechanical properties.     

Mutations in the retinal guanylate cyclase (RETGC-1) gene in dominant cone-rod dystrophy

The dominant cone-rod dystrophy gene CORD6 has previously been mapped to within an 8 cM interval on chromosome 17p12-p13. The retinal- specific guanylate cyclase gene (RETGC-1), which maps to within this genetic interval and previously was implicated in Leber's congenital amaurosis, was screened for mutations within this family and in a panel of small families and individuals with various cone and cone- rod dystrophy phenotypes. A missense mutation (E837D) was identified in affected members of the CORD6 family, as well as a second missense mutation (R838C) in three other families with dominant cone-rod dystrophy. RETGC-1 is only the fourth gene to be implicated in cone-rod dystrophy and this is the first report of dominant mutations in this gene.