Targeted stent use in clinical practice based on evidence from the Basel Stent Cost Effectiveness Trial (BASKET): reply

We thank Agostini Pierfranco and colleagues for their interestin our analysis of the     

Maplets for correspondence-based object recognition.

We present a correspondence-based system for visual object recognition with invariance to position, orientation, scale and deformation. The system is intermediate between high- and low-dimensional representations of correspondences. The essence of the approach is based on higher-order links, called here maplets, which are specific to narrow ranges of mapping parameters (position, scale and orientation), which interact cooperatively with each other, and which are assumed to be formed by learning. While being based on dynamic links, the system overcomes previous problems with that formulation in terms of speed of convergence and range of allowed variation. We perform face recognition experiments, comparing ours to other published systems. We see our work as a step towards a reformulation of neural dynamics that includes rapid network self-organization as essential aspect of brain state organization.     

Mechanism of action of the epileptogenic drug pentylenetetrazol on a cloned neuronal potassium channel

The action of the epileptogenic agent pentylenetetrazol (PTZ) on a cloned potassium channel of the rat brain was studied. The Kv1.1 channel was expressed in oocytes ofXenopus laevis and potassium currents were investigated in outside-out and inside-out membrane patches. The results show that PTZ increased the multi-channel potassium currents at strongly negative potentials and decreased them at potentials positive to −35 mV both in outside-out and inside-out membrane patches. The extent and manner of PTZ action, the concentration dependence as well as the onset and time course of the PTZ effect were the same both in outside-out and inside-out membrane patches. The single-channel potassium currents showed an increase in open probability and frequency of opening and a decrease in close time at −50 mV and vice versa at 0 mV with application of PTZ. The amplitude of single-channel current, the open time and the latency to the first channel opening remained almost unchanged under PTZ. The results indicate that PTZ acts via the cell membrane and influences the membrane-associated part of the potassium channel. Thereby, PTZ accelerates the transition from the inactivated to the open state of the channel at strongly negative potentials and reduces it at slightly negative and positive potentials. This mechanism may be the basis for a gate function which is in favour of the development of epileptic discharges.     

Evaluation of postsurgical crestal bone levels adjacent to non‐submerged dental implants

In most of the studies on long-term radiographic evaluations of crestal bone levels adjacent to dental implants, no baseline radiographs taken immediately post-surgically had been obtained.The aim of this study was to test the reproducibility of a simple radiographic method for linear measurements of changes in bone levels and to evaluate changes in crestal bone levels adjacent co non-submerged ITI® implants 1 year following the surgical procedure. From 128 patients enrolled in a clinical and radiographic longitudinal study 40 patients also had radiographs taken immediately postsurgically. They were, however, not obtained as “identical” images. The radiographs were mounted onto slides and projected on a screen. Mesially and distally from 57 implants triplicate linear measurements of the distance implant shoulder to bone crest were taken, using known dimensions of the implants as internal reference distances. The median difference of 213 (out of 228 possible) duplicate measurements was 0.00 mm (ranging from ?1.72 mm to +1.47 mm when comparing the second co the third reading). Some 81% of the double measurements were within ±0.5 mm and the precision was 0.30 mm. In the immediate postoperative radiographs the median mesial bone level was located at 2.07 mm (distally 2.19 mm) from the implant shoulder. A statistically significant amount of bone loss in the first year was observed mesially (median=?0.78 mm) and distally (0.85 mm)(Wilcoxon matched pairs signed rank test ±0.001). No statistically significant influence of the implant location, the implant length, type of the implant (screw; cylinder) was observed (Kruskal-Wallis P>0.05).The age of the patients was not correlated significantly to the amount of bone loss observed. In conclusion, methodological limitations existed when evaluating linear bone changes in non-identical radiographs using reference dimensions of the implants. The amount of postsurgical bone loss estimated in other studies was confirmed when using an immediate postoperative radiograph as a baseline.     

Lack of Nonshivering Thermogenesis in Infants Anesthetized with Fentanyl and Propofol

Background: Sweating, vasoconstriction, and shivering have been observed during general anesthesia. Among these, vasoconstriction is especially important because-once triggered-it minimizes further hypothermia. Surprisingly, the core-temperature plateau associated with vasoconstriction appears to preserve core temperature better in infants and children than adults. This observation suggests that vasoconstriction in anesthetized infants may be accompanied by hypermetabolism. Consistent with this theory, unanesthetized infants rely on nonshivering thermogenesis to double heat production when vasoconstriction alone is insufficient. Accordingly, the authors tested the hypothesis that intraoperative core hypothermia triggers nonshivering thermogenesis in infants.

Methods: With Ethics Committee approval and written parental consent, the authors studied six infants undergoing abdominal surgery. All were aged 1 day to 9 months and weighed 2.4-9 kg. Anesthesia was maintained with propofol and fentanyl. The infants were mechanically ventilated and allowed to cool passively until core (distal esophageal) temperatures reached 34-34.5 degrees Celsius. Oxygen consumption-the authors' index of metabolic rate- was recorded throughout cooling. Because nonshivering thermogenesis triples circulating norepinephrine concentrations, arterial blood was analyzed for plasma catecholamines at [nearly equal] 0.5 degrees Celsius intervals. Thermoregulatory vasoconstriction was evaluated using forearm - fingertip, skin-surface gradients, with gradients exceeding 4 degrees Celsius, indicating intense vasoconstriction. The patients were subsequently rapidly rewarmed to 37 degrees Celsius. Regression analysis was used to correlate changes in oxygen consumption and plasma catecholamine concentrations with core temperature.

Results: All patients were vasoconstricted by the time core temperature reached 36 degrees Celsius. Further reduction in core temperature to 34-34.5 degrees Celsius did not increase oxygen consumption. Instead, oxygen consumption decreased linearly. Hypothermia also failed to increase plasma catecholamine concentrations.     

Inhibition of homotypic aggregation of a human Burkitt-lymphoma cell line

The molecules involved in homotypic aggregation of the human Burkitt-lymphoma cell line Raji were investigated by inhibition of reaggregation with carbohydrates and glycoconjugates, by inhibition of glycosylation, and enzyme treatment of the cell surface. Complete inhibition of reaggregation was achieved with bovine submaxillary mucin. Asialomucin, on the other hand, was not effective in this assay. Another potent inhibitor of reaggregation was the ganglioside GMI. The common carbohydrate structure of these molecules is NeuNAc-(gal)-galNAc. Lactosamine, fucosyllactosamine, sialyllactosamine, complex mannose type, or Thomsen-Friedenreich antigen sequences are not involved in aggregation. Neuraminidase and chloroquine also abolished agglutination of cells. The finding that mucin, but not asialomucin, inhibits the reaction, demonstrates the importance of sialic acid in this process. Homotypic aggregation was shown to be resistant to trypsin. Using the glycosylation inhibitor tunicamycin we show that N-glycosidically linked carbohydrate chains are involved in aggregation. Swainsonine or castanospermine, which inhibit processing of terminal sialyllactosamines to the mannose core, did not interfere with the reaction supporting the results of the inhibition assay. The data presented suggest the involvement of 2 molecules in homotypic aggregation of human Burkitt-lymphoma cells. One component is a lectin-like molecule containing N-linked carbohydrate chains. The other component carries the neuraminidase-sensitive and trypsin-resistant determinant NeuNAc-(gal)-galNAc and, therefore, appears to be a glycolipid. This proposed lectin-carbohydrate interaction in homotypic aggregation is further supported by the frequently observed dependence of lectins on divalent cations as indicated by inhibition of aggregation with EDTA and EGTA.     

Gentamicin pharmacokinetics in term neonates receiving extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) may affect the pharmacokinetics of certain drugs. The objectives of this study were to determine (1) the pharmacokinetics of gentamicin in neonates on ECMO and compare them to reported values for a similar patient population not on ECMO, (2) if the pharmacokinetics of gentamicin differ between venous-venous and venous-arterial bypass, and (3) if the pharmacokinetics of gentamicin are affected by oxygenator surface area (0.6 m2 vs 0.8 m2 oxygenators). The medical records of 29 term neonates who received gentamicin while on ECMO were reviewed. Data collected included gentamicin dosage, peak and trough serum concentrations determined at steady state, duration of treatment, time on ECMO, daily weights, and pertinent laboratory values. An initial dosage of gentamicin 2.5 mg/kg every 18 hours is suggested for term neonates on ECMO. Dosage adjustments should be based on gentamicin serum concentrations, and modifications may also be required after ECMO.     

Medullary sponge kidneys and unilateral Wilms tumour in a child with Beckwith-Wiedemann syndrome

The occurrence of a Wilms tumour in a 4-year-old girl with bilateral medullary sponge kidney, Beckwith-Wiedemann syndrome and congenital hemihypertrophy demonstrates the close relationship between these disorders. Another six cases from the literature with congenital hemihypertrophy and with medullary sponge kidney are discussed, two of them also developed intra-abdominal neoplasm.