Comparative healing response after sirolimus- and paclitaxel-eluting stent implantation in a pig model of restenosis

OBJECTIVE

We compared local vessel healing and inflammatory responses associated with nonoverlapping sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES).

BACKGROUND

Sirolimus and paclitaxel may have different effects on vascular healing. In the present study, we analyzed the local histologic effects of drug-eluting stents (DES).

METHODS

We placed 43 stents (22 PES and 21 SES) in 16 Yucatan minipigs. Stents were randomly assigned and placed in the left anterior descending, circumflex, or right coronary arteries (one stent per artery), covering a region previously injured by balloon angioplasty.

RESULTS

Histopathologic analysis showed that the distribution of injury scores was similar between the two stent groups, reflecting the homogeneity of coronary injury secondary to balloon overstretch. Electron microscopy showed complete endothelialization in most cases. Incomplete endothelialization was present in 12.5% of PES and almost 20% of SES at 30 days. In the PES group, moderate to severe inflammation was found in eight arteries, whereas only one vessel had moderate inflammation in the SES group. Severe inflammation was observed significantly more often in the PES than in the sirolimus group (P = 0.006). With the PES group, stent struts overlying side branches had a significantly higher frequency of poor endothelialization scores than did stent struts that did not overlay side branches (P = 0.006).

CONCLUSIONS

In this preclinical study in a pig model of in-stent restenosis, implantation of nonoverlapping DES was associated with local inflammatory reactions and decreased endothelial repair. Impaired endothelialization was visualized in the struts overlying side branches.

Intramuscular midazolam versus intravenous diazepam for treatment of seizures in the pediatric emergency department: a randomized clinical trial

AIM

To compare the therapeutic efficacy of intramuscular midazolam (MDZ-IM) with that of intravenous diazepam (DZP-IV) for seizures in children.

DESIGN

Randomized clinical trial.

SETTING

Pediatric emergency department.

PATIENTS

Children aged 2 months to 14 years admitted to the study facility with seizures.

INTERVENTION

Patients were randomized to receive DZP-IV or MDZ-IM.

MAIN MEASUREMENTS

Groups were compared with respect to time to treatment start (min), time from drug administration to seizure cessation (min), time to seizure cessation (min), and rate of treatment failure. Treatment was considered successful when seizure cessation was achieved within 5min of drug administration.

RESULTS

Overall, 32 children (16 per group) completed the study. Intravenous access could not be obtained within 5min in four patients (25%) in the DZP-IV group. Time from admission to active treatment and time to seizure cessation was shorter in the MDZ-IM group (2.8 versus 7.4min; p<0.001 and 7.3 versus 10.6min; p=0.006, respectively). In two children per group (12.5%), seizures continued after 10min of treatment, and additional medications were required. There were no between-group differences in physiological parameters or adverse events (p=0.171); one child (6.3%) developed hypotension in the MDZ-IM group and five (31%) developed hyperactivity or vomiting in the DZP-IV group.

CONCLUSION

Given its efficacy and ease and speed of administration, intramuscular midazolam is an excellent option for treatment of childhood seizures, enabling earlier treatment and shortening overall seizure duration. There were no differences in complications when applying MDZ-IM or DZP-IV.

Physical properties of some zinc phosphate and polycarboxylate cements

Several physical properties were measured for two zinc phosphate and three polycarboxylate cements. The specimens were tested in compression 24 h after they had been made. Two series of specimens were examined. In one series the cement powders were given a correct treatment, protected from atmospheric humidity. In the other series the powders were exposed for 1 week to ambient conditions with the temperature varying between 20 degrees and 24 degrees C and the relative humidity between 40% and 59%. The zinc phosphate cements were characterized by high values of modulus of elasticity and by plastic deformations less than 0.2%. The polycarboxylate cements were more flexible and also exhibited large plastic deformations. Compared with the zinc phosphate cements, therefore, the polycarboxylate cements had high values of resilience and toughness. The storing of cement powders exposed to atmospheric humidity for 1 week did not change the measured properties of the polycarboxylate cements. However, both strength and resilience were significantly reduced for one phosphate cement.

Efficient bioaccumulation of tungsten by Escherichia coli cells expressing the Sulfitobacter dubius TupBCA system

Tungsten (W) is a valuable element with considerable industrial and economic importance that belongs to the European Union list of critical metals with a high supply risk. Therefore, the development of effective and new methods for W recovery is essential to ensure a sustainable supply. In the present study, the Sulfitobacter dubius W transport system TupABC was explored in order to demonstrate both its functionality in Escherichia coli cells and to construct a bioaccumulator (EcotupW). The complete gene cluster tupBCA or partial gene cluster tupBC were cloned in an expression vector and transformed into E. coli. Metal accumulation was evaluated when each construct strain was grown with three separate metal oxyanions (tungstate, molybdate or chromate). The specificity of the bioaccumulator was determined by competition assays using cells grown with mixed solutions of metal oxyanions (W/Mo and W/Cr). The results showed the relevance of the TupA protein in the TupABC transporter system to W-uptake and also allowed Mo and Cr accumulations, although with amounts 1.7 and 2.9-fold lower than W, respectively. To identify the importance of the valine residue in the accumulation efficiency of the VTTS motif, site-directed mutagenesis of tupA was performed. A mutant with a threonine residue, instead of the respective valine, confirmed that W was internalized by nearly double the amount compared to the native form. The findings indicated that cells carrying the native S. dubius TupABC system were great W-bioaccumulators and could be promising tools for W recovery.

Guided bone regeneration using osteopatite granules and polytetrafluoroethylene membranes

Granules of a modified hydroxyapatite, Osteopatite, were implanted in the right posterior tibiae of adult rabbits. We studied the extent of bone regeneration in bone holes. In the right tibiae, that were filled with granules of this biomaterial covered with a polytetrafluoro-ethylene (PTFE) membrane using, as a control, uncovered granules. In the left tibia, an empty hole was covered with PTFE membrane and a second hole was left empty to be used as a control. A histomorphometric study was carried out using light microscopy, four and eight weeks after the surgery. The covered granules presented a higher percentage of bone contact than the uncovered ones, and it was also possible to observe a better bone tissue organization, mainly produced by the immobilization action of the PTFE membrane. Empty bone defects covered with PTFE membranes, two months after implantation, presented large areas of Haversian bone and direct bone contact to the PTFE membrane.

Catheter-based transendocardial delivery of autologous bone-marrow-derived mononuclear cells in patients listed for heart transplantation

Growing evidence suggests that transplantation of autologous bone-marrow mononuclear cells (ABMMNCs) can improve the perfusion and contractile function of ischemic myocardium. This procedure could potentially benefit transplant candidates awaiting a donor heart. To study the safety and feasibility of ABMMNC injection, we performed a prospective, nonrandomized, open-label study in 5 heart transplant candidates with severe ischemic heart failure. Each patient underwent baseline single-photon emission computed tomography, a ramp treadmill protocol, 2-dimensional echocardiography, 24-hour Holter monitoring, and signal-averaged electrocardiography, which were repeated at 2 and 6 months. Transendocardial delivery of ABMMNCs was done with the aid of electromechanical mapping to identify viable myocardium. Each patient received 15 ABMMNC injections of 0.2 cc each. There were no deaths, significant arrhythmias, or other major complications. The ABMMNC injection reduced the amount of ischemic myocardium (not statistically significant). More important, exercise test results improved significantly. Myocardial volume oxygen consumption increased from 10.6 +/- 3 mL/kg/min (baseline) to 16.3 +/- 7 mL/kg/min (2 months) and 23 +/- 7 mL/kg/min (6 months) (P = 0.0091). In 4 of the 5 cases, this was such an improvement that the patients were no longer eligible for cardiac transplantation. In addition, metabolic equivalents improved from 3.03 +/- 0.66 (baseline) to 4.65 +/- 1.99 (2 months) and 6.5 +/- 2.0 (6 months) (P = 0.0092). In conclusion, ABMMNC injections were performed safely and resulted in improved exercise capacity. This technique may hold promise as an alternative to medical management in patients with severe ischemic heart failure who are ineligible for conventional revascularization.

[Prevention of alveolar bone resorption with the use of hydroxyapatite granules]

The authors describe in review the alveolar absorption according to bone physiology, and the absorption prevention using hydroxylapatite. Finally it is pointed the good preliminary results in a 30 patients study during 8 months using hydroxylapatite (OSTEOPATITE) and plaster particles in alveolar absorption prevention.

[2 amalgam formulation mechanisms with high copper alloys]

Two high copper-containing amalgam alloys, one of them gas atomized and the other water atomized were used to study the reaction mechanism with mercury. Normal and subtrituration time were used. The observations of structures and evaluation of compressive strengths allowed the understanding of two different mechanisms of reaction.

[Contralateral occlusion of the internal carotid artery in the study of carotid stenosis using Doppler ultrasonography]

INTRODUCTION AND AIMS

The degree of stenosis measured by Doppler ultrasonography in patients with contralateral occlusion of the internal carotid artery (ICA) is assumed to be overestimated. We propose to measure the extent to which this phenomenon affects the capacity of Doppler ultrasonography to classify stenoses.

PATIENTS AND METHODS

A retrospective study of 47 patients was conducted using Doppler ultrasonography and digital subtraction angiography; all subjects had confirmed unilateral occlusion of the ICA and stenoses of the contralateral ICA. Curves were traced plotting the degree of stenosis against the peak systolic velocity (PSV) and its ratio in the ICA and in the common carotid artery (VICA/VCCA). The curves were compared with their equivalents with no contralateral occlusion found in the literature. Later, the cases of stenosis were classified into groups of less than 50, 50-69 and more than 70%, and the main statistical values were calculated.

RESULTS

The PSV in the stenoses between 40-50% presents more than 1 standard deviation (SD) above the mean. There were no significant deviations in other degrees of stenosis (p > 0.4). The VICA/VCCA showed a similar parallelism, but with deviations lower than 1 SD (p = 0.56). Seventeen per cent of the stenoses were over-classified, and this conditioned a sensitivity of 84, 71 and 100%, and a specificity of 100, 94 and 88% for the groups of less than 50, 50-69 and over 70%, respectively. The VICA/VCCA over-classified 41% of the stenoses; sensitivity was seen to be 56, 43 and 100% and specificity was 90, 64 and 87%. Diagnostic accuracy of the PSV and VICA/VCCA stands at 83 and 57%, respectively.

CONCLUSIONS

Contralateral occlusion leads to over-classification of the PSV. There is a tendency to over-classify, although this does not affect the overall diagnostic accuracy. The VICA/VCCA does not offer greater diagnostic accuracy in classifying stenoses with contralateral occlusion.

[Visceral leishmaniasis and HIV infection: the diagnostic and therapeutic problems]

We present the case of an HIV-seropositive drug addict patient whose seropositivity was unknown until admission to hospital, where he presented with a clinical picture of fever splenomegaly and weight loss. A diagnosis of visceral leishmaniasis was established. We stress the diagnostic difficulties well expressed in the need to repeat the bone marrow aspirate to detect the presence of leishmanias. The lack of response to conventional antimonial therapy is discussed as well as the role of pentamidine as an alternative therapy.